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Homeostasis and Human Body Systems


Homeostasis and Human Body Systems Imagine you are playing softball on a warm summer day. Write down two ways that your body would adjust to keep you cool and to keep ... – PowerPoint PPT presentation

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Title: Homeostasis and Human Body Systems

Homeostasis and Human Body Systems
  • Imagine you are playing softball on a warm summer
    day. Write down two ways that your body would
    adjust to keep you cool and to keep your muscles

Key Ideas
  • How does a change in the external environment
    affect an organism?
  • How does an organism respond to changes, and what
    happens if the organism fails to respond to
  • What organ systems do humans need in order to
  • How is the human body organized?
  • What is Homeostasis?

Human Body Systems
  • Which body systems are the basketball players
  • Recall levels of organization in an organism
  • Cells
  • Tissues
  • Organs
  • Organ system

What is Homeostasis?
  • The process by which organisms maintain a
    relatively stable internal environment
  • How does the human body maintain homeostasis?
  • The eleven organ systems of the human body work
    together to maintain homeostasis.
  • Homeostasis is the process by which organisms
    keep internal conditions relatively constant
    despite changes in external environments.

To help understand homeostasis lets think about
how a thermostat works
Decrease room temperature
Increase room temperature
Increase room temperature
A Changing Environment
  • The external environment around an organism is
    constantly changing.
  • These changes threaten the stability of an
    organisms internal environment.
  • The maintenance of a relatively stable internal
    environment is called homeostasis.

  • Change in seasons, light level, water
    availability, or other changes to the external
    environment can change an organisms internal
  • Different organisms deal with these changes in
    different ways.
  • In a colder environment, for example, organisms
    may eat more food, puff out fur or feathers, fly
    to warmer areas, or hibernate.

Responses to Change
  • Organisms must carry out many chemical reactions
    to grow, obtain energy, and reproduce.
  • Many organisms also move, breathe, produce heat,
    and do other tasks.
  • All of these activities require the organism to
    maintain a relatively stable internal environment.

Responses to Change
  • Organisms detect and respond to both internal and
    external environments in a variety of ways.
  • Detection and response can take place at both the
    cellular and organismal level.
  • Failure to respond to change can result in an
    organisms death.

Now lets take a look at how plants maintain
  • Leaves of plants are covered on the top and
    bottom by epidermis made of a layer of tough,
    irregularly shaped cells.
  • The epidermis of many leaves is also covered by
    the cuticle.
  • Together, the cuticle and epidermal cells form a
    waterproof barrier that protects tissues and
    limits the loss of water through evaporation.

Stomata (singular stoma), are pore-like
openings in the underside of the leaf that allow
carbon dioxide and oxygen to diffuse into and out
of the leaf. Each stoma consist of
two guard cells, the specialized
cells in the epidermis that control
the opening and closing of stomata by
responding to changes in water
Responses to Change
  • The pores on a plants leaf help the plant to
    regulate water loss and gas exchange.
  • During the day, tissues perform photosynthesis.
  • Guard cells near these active tissues swell with
    water. This opens pores, letting in the carbon
    dioxide that is needed for photosynthesis

Responses to Change
  • Open pores also allow water to exit the leaf.
  • At night, when photosynthesis slows, water exits
    the guard cells.
  • The cells shrink and close the pores, preventing
    excess water loss at night.

Control of Stomatal Opening
Responses to Change
  • If an organism is not able to respond to changes
    in its environment, disease or death can result.
  • Consider what would happen if a plant could not
    slow water loss.
  • When the amount of water in a plants tissues got
    too low, the plant would wilt, collapse, and die.

Responses to Change
  • Humans must also control internal water levels.
  • About 2/3 of the human body is made of water.
  • If a person loses too much water, by sweating or
    urination, dehydration will occur.
  • Dehydration causes blood pressure to drop
    significantly until death occurs.

Responses to Change
  • Some deep-water fish must be adapted to deal with
    high water pressure.
  • The coelacanth is a fish that lives in the deep
    waters off the coast of Africa.
  • At the depth where the fish lives, water pressure
    is several hundred times greater than the water
    pressure at the oceans surface.

Responses to Change
  • If a person tried to swim at this pressure, the
    persons body would be crushed.
  • The coelacanth will actually die in the
    low-pressure environment at the waters surface.
  • The coelacanths body is adapted to require high
    pressure, in order to keep gases from bubbling
    out of the fishs bloodstream and blocking flow
    to the fishs heart.

Humans and Homeostasis
  • Humans are constantly subjected to environmental
    stresses that threaten to upset the delicate
    balance that exists within our cells and tissues.
  • Humans require multiple systems for digestion,
    respiration, reproduction, circulation, movement,
    coordination, and immunity.
  • These systems interact to maintain homeostasis.

  • Summary of Human Body Systems

Humans and Homeostasis
  • The organs and systems of the human body help to
    provide all of the cells with their basic needs.
  • Each cell needs a constant supply of nutrients
    and oxygen, removal of waste materials, and
    protection from disease.
  • With the exception of the reproductive system,
    each of the human body systems performs a task
    that helps stabilize the bodys internal

Humans and Homeostasis
  • In the human body, the main components of
    homeostasis are the following
  • the concentration of salts
  • The pH of the internal environment
  • The concentration of nutrients and waste products
  • The concentration of oxygen and carbon dioxide
  • The volume and pressure of extracellular fluid

Humans and Homeostasis
  • When these five components are adequately
    controlled, homeostasis is maintained and the
    body is most likely healthy.
  • No organ system can maintain homeostasis by
  • Organ systems must work together in a
    synchronized manner.

Humans and Homeostasis
  • For example, the concentration of oxygen and
    carbon dioxide is controlled by four different
    body systems.
  • First, the respiratory system brings oxygen into
    and carbon dioxide out of the body.
  • The circulatory system distributes the oxygen to
    the bodys tissues and picks up carbon dioxide.

Humans and Homeostasis
  • If the level of carbon dioxide gets too high, the
    nervous system instructs the muscular system to
    make the muscles around the rib cage work harder.
  • This action allows the lungs of the respiratory
    system to breathe faster, to get rid of excess
    carbon dioxide.

Key Ideas
  • How does a change in the external environment
    affect an organism?
  • The external environment around an organism is
    constantly changing. These changes threaten the
    stability of an organisms internal environment.
  • How does an organism respond to changes, and what
    happens if the organism fails to respond to
  • Organisms detect and respond to change in a
    variety of ways both at the cellular level and
    at the organismal level. Failure to respond to
    change can result in an organisms death.

Key Ideas
  • What organ systems do humans need in order to
  • Humans require multiple systems for digestion,
    respiration, reproduction, circulation, movement,
    coordination, and immunity. The systems interact
    to maintain homeostasis.

Human Body Systems
  • Alternately bend and straighten your arms or legs
    while feeling the muscles in the front and the
  • Write down what you feel when the limb is
    straightened and what you feel when the limb is

Key Ideas
  • How do the skeletal and muscular systems help the
    body maintain homeostasis?
  • How does the integumentary system help the body
    maintain homeostasis?
  • How do the nervous and endocrine systems help the
    body maintain homeostasis?

Key Ideas
  • How do the digestive and excretory systems help
    the body maintain homeostasis?
  • How do the circulatory and respiratory systems
    help the body maintain homeostasis?

Skeletal and Muscular Systems
  • The skeletal and muscular systems enable movement
    and provide support for tissues and organs.
  • Bones and muscles work together to make movement
  • The ability to move increases the chance of
    survival by allowing a person to gather food,
    seek shelter, and escape from danger.

Skeletal and Muscular Systems
  • The skeleton provides an anchor for the muscles
    that move the body.
  • There are 206 bones in a human adult

Axial skeleton supports the central axis of the
body skull, vertebral column, and rib
cage Appendicular skeleton bones of arms and
legsWhat do you think is a better model of a
bone, a stick of chalk or a sponge? The chalk
may look more like a bone but the sponge shows
what the structure actually looks like inside.
What passes through the tubes and spaces inside
Blood vessels and nerves PERIOSTEUM Bone is
surrounded by a tough layer of connective
tissue Haversian canals Network of tubes that
contain blood vessels and nerves.
Bone marrowCavities that contain a soft tissue
  • There are two types of bone marrow
  • yellow and red
  • Yellow marrow is made up primarily of fat
  • Red marrow produces red blood cells, some kinds
    of white blood cells, and cell fragments
    called platelets.

Cartilage -Cells are scattered in a network of
protein fiberstough collagen and flexible
  • Cartilage does not contain blood vessels.
  • Cartilage cells must rely on nutrients from the
    tiny blood vessels in surrounding tissues.
  • Cartilage is dense and fibrous, it can support
    weight, despite its extreme flexibility

Ossification -Cartilage is replaced by bone
during the process of bone formation
  • Osteoblasts create bone.
  • Osteocytes maintain the cellular activities of
  • Osteoclasts break down bone Force must be
    placed on bone for ossification to occur, because
    it is force that stimulates the osteoblasts to
    secrete the minerals that replace cartilage

What effect do you think an exercise such as
walking would have on the bones of the legs?
  • It would stimulate ossification, so the bones
    would contain more minerals and be stronger.
  • What do you think might happen to the bones that
    are not exposed to force, such as the bones of
    astronauts in zero gravity?
  • The bones would lose minerals because of lack of
    force exerted on them, so they become weaker

  • Bone formation occurs in babies and children
  • Seven months before birth cartilage is gradually
    replaced by bone
  • When a person grows, the growth plates are
    lengthening in the long bones
  • When you stop growing, those growth plates are
    then filled in with bone
  • Adults do retain some cartilage
  • Tip of nose, ears, where ribs attach to the

  • Bone formation also occurs when a bone is broken
  • Osteoclasts remove damaged bone tissue
  • Osteoblasts produce new bone tissue
  • The repair of a broken bone can take months
    because the process is slow and gradual

Depending on its type of movement, a joint is
classified as immovable, slightly movable, or
freely movable
  • Immovable Joints
  • Where the bones in the skull meet
  • Slightly Movable Joints
  • The joints between the two bones of the lower leg
    and the joints between adjacent vertebrae are
    examples of slightly movable joints.
  • Freely Movable Joints
  • Ball-and-socket joints permit circular
    movementthe widest range of movement
  • Hinge joints permit back-and-forth motion, like
    the opening and closing of a door
  • Pivot joints allow one bone to rotate around
  • Saddle joints permit one bone to slide in two

  • Structure of joints
  • Ends of bones are covered with a smooth layer of
  • Joints are surrounded by a fibrous joint capsule
    that helps hold bones together

  • Tendons attach muscles to bones.
  • When muscles contract, tendons pull on bones to
    cause movement.
  • LIGAMENTS strip of tough connective tissue that
    hold bones together
  • Synovial fluid lubricates the ends so bones can
    slide past each other smoothly

Opposing Muscles in the Arms
Skeletal and Muscular Systems
  • What are the three types of muscle?
  • Skeletal
  • Smooth
  • Cardiac

Skeletal Muscle
  • Skeletal muscles are usually attached to bones
  • Skeletal muscles are responsible for such
    voluntary movements as typing on a computer
    keyboard, dancing, or winking an eye
  • When viewed under a microscope at high
    magnification, skeletal muscle appears to have
    alternating light and dark bands or stripes
    called striations. For this reason, skeletal
    muscle is sometimes called striated muscle
  • Most skeletal muscles are controlled by the
    central nervous system.

Smooth Muscles 
  • Smooth muscles are usually not under voluntary
  • A smooth muscle cell is spindle-shaped, has one
    nucleus, and is not striated
  • Smooth muscles are found in hollow structures
    such as the stomach, blood vessels, and the small
    and large intestines
  • Smooth muscles move food through your digestive
    tract, control the way blood flows through your
    circulatory system, and decrease the size of the
    pupils of your eyes in bright light.

Cardiac Muscle 
  • Cardiac muscle is found in just one place in the
    bodythe heart
  • The prefix cardio- comes from a Greek word
    meaning heart.
  • Cardiac muscle is striated like skeletal muscle,
    although its cells are smaller.
  • Cardiac muscle cells usually have one nucleus,
    but they may have two.
  • Cardiac muscle is similar to smooth muscle
    because it is usually not under the direct
    control of the central nervous system

Muscle Contraction
  • A muscle contracts when the thin filaments in the
    muscle fiber slide over the thick filaments
  • The energy for muscle contraction is supplied by
  • Neuromuscular junction
  • The point of contact between a motor neuron and a
    skeletal muscle cell

How do body builders get muscles that increase in
  • Muscles that are exercised regularly stay firm
    and increase in size by adding more material to
    the inside of the muscle cells

Integumentary System
  • Skin is the largest organ of the human body.
  • Skin makes up about 7 of your total body weight.
  • The skin, hair, and nails form the integumentary

Integumentary System
  • The integumentary system does the following
  • protects the body from injury and UV radiation
  • defends against disease
  • helps regulate body temperature
  • prevents the body from drying out


Integumentary System
  • Waterproofing
  • The epidermis is the outermost layer of skin.
  • It is made of flattened, dead cells composed of a
    protein called keratin.
  • Keratin is also found in nails and hair.

Integumentary System
  • Keratin makes the skin tough and waterproof.
  • Glands in the dermis, the layer of skin under the
    epidermis, secrete oil that lubricates the skin.
  • Without the protection of keratin and oil, our
    bodies would lose water through evaporation or
    absorb water from the environment.

Integumentary System
  • Disease Prevention
  • The epidermis forms a tight barrier that keeps
    bacteria out and protects the body from disease.
  • Damage to large areas of skin allows bacteria to
    enter the body freely.
  • This lack of protection is one reason why severe
    burns are so dangerous.

Integumentary System
  • UV Prevention
  • The lower layers of the epidermis contain cells
    that make melanin, a pigment that absorbs UV
  • This absorption prevents DNA damage, which can
    cause skin cancer.

Integumentary System
  • Temperature Regulation
  • A network of blood vessels and nerves in the
    dermis help regulate body temperatures.
  • Sweat glands also help remove excess body heat
    through the evaporation of sweat.

The Nervous System
What is the function of the nervous system?
  • It controls and coordinates functions throughout
    the body and responds to external and internal

  • Neuron cells that transmit impulses
  • What is an impulse?
  • Message carried by the nervous system as
    electrical signals

3 Types of Neurons
  • Sensory carry impulses from sense organs to the
    spinal cord
  • Motor carry impulses from brain and spinal cord
    to muscles and glands
  • Interneurons connect sensory and motor neurons
    and carry impulses between them

Typical neuron Draw the direction an impulse
Cell body largest part of a neuron contains
the nucleus and most of the cytoplasmDendrites
short, branched extensions spreading out from
the cell body receive impulsesAxon long thin
fiber that carries impulses away from the cell
bodyAxon terminal end of an axon that sends
impulses to another neuron
Nerve bundles of dendrites and axons all
clustered together
  • How an impulse occurs
  • A nerve impulse begins when a neuron is
    stimulated by another neuron or by its
  • The impulse travels along the axon away from the
    cell body and toward the axon terminal.
  • At the end of a neuron, the impulse reaches an
    axon terminal.
  • Usually the neuron makes contact with another
    cell at this location neuron, muscle cell

Synapse the location at which a neuron can
transfer an impulse to another cell aka
synaptic cleft, gap
Nervous and Endocrine Systems
  • The nervous system is composed of signaling cells
    that collect and respond to information about the
    bodys internal and external environment.
  • The central nervous system (CNS) includes the
    brain and spinal cord.
  • The brain is the bodys main processing center.
    It coordinates the bodys efforts to maintain

  • Cerebrum largest and most prominent region of
    human brain
  • Controls voluntary or conscious activities of the
  • Site of intelligence, learning, and judgment
  • Two hemispheres each half controls the opposite
    side of the body

  • Cerebellum second largest region located at
    back of skull
  • Coordinates and balances the actions of muscles
    so the body can move gracefully and efficiently
  • Brain Stem aka medulla oblongata and pons
    connects brain and spinal cord located just
    below cerebellum
  • Regulates flow of information between brain and
    rest of the body
  • Controls blood pressure, heart rate, breathing,
    and swallowing

  • Thalamus found between brain stem and
    cerebrum receives messages from sense organs
    relays information to the proper region of the
    cerebrum for further processing
  • Hypothalamus located between brainstem and
    cerebrum control center for recognizing and
    analyzing hunger, thirst, anger, fatigue, and
    body temperature
  • aka-the thermostat

Structure of the Human Brain
Nervous and Endocrine Systems
  • The spinal cord is a column of nerves that links
    the brain to most of the peripheral nervous
    system (PNS).
  • The PNS contains sensory and motor nerves.
  • Sensory nerves carry information to the central
    nervous system from sense organs such as the

What are the 5 types of sensory receptors?
There are five general categories of sensory
  • Pain receptors
  • Thermo-receptors
  • Mechano-receptors
  • Chemo-receptors
  • Photo-receptors

Where are these receptors located?
  • Pain receptors throughout body except the brain
  • Thermoreceptors skin, body core, and

  • Mechanoreceptors
  • skin, skeletal muscles, and inner ear they
    are sensitive to touch, pressure, stretching of
    muscles, sound and motion
  • Chemoreceptors
  • nose and taste buds
  • Photoreceptors
  • eyes

Vision - eye
  • Photoreceptors arranged in a layer in the
    retina (layer in back of eye)
  • rods extremely sensitive to light
  • cones distinguish colors

Hearing and Balance ear
  • Tympanum
  • aka ear drum
  • Hammer, anvil, and stirrup
  • three tiny bones
  • COCHLEA has tiny hair cells that move with
    sound vibrations and sends message to nerve
  • SEMICIRCULAR CANALS filled with fluid and tiny
    hairs they can sense which direction your head
    is in due to gravity
  • EAR INFECTION usually in middle ear due to
    Eustachian tube

  • Smell and Taste nose and mouth
  • Ability to sense chemicals
  • Chemoreceptors line your nose and taste buds
    located in mouth
  • Touch skin
  • The places that are more sensitive to touch
    fingers, toes, and face
  • Has more sensory receptors

Nervous and Endocrine Systems
  • Motor nerves carry commands from the central
    nervous system to muscles and other organs, such
    as glands.

Also involved with reflexes ex) you touch a hot
stove your hand pulls back before you sense
the pain Reflex Arc - this information goes
from hand to spine back to hand again it never
reaches the brain because it would take too long

Nervous and Endocrine Systems
  • Motor nerves are grouped into two independent
  • autonomic nervous system
  • somatic nervous system

Nervous and Endocrine Systems
  • Motor nerves that are not under conscious control
    are part of the autonomic nervous system
  • Some ways that the autonomic nervous system
    maintains homeostasis include
  • stimulating digestion after a meal
  • slowing down the heart rate after exercise
  • preparing the body for stressful situations

Nervous and Endocrine Systems
  • Motor nerves that are under conscious control are
    part of the somatic nervous system.
  • The nerves we use to signal our legs or arms to
    move are part of the somatic nervous system.
  • The somatic system also operates without
    conscious control, to help us maintain balance.

  • Comparing Autonomic and Somatic Nervous Systems

Drugs and the Nervous System
Key Concept Questions What are the different
classes of drugs that directly affect the central
nervous system? What is the effect of alcohol on
the body?
What is a drug?
  • Any substance other than food, which changes the
    structure or function of the body
  • Ex) antibiotics, cold medicine, cocaine, heroin
  • The most powerful drugs are those that affect the
    nervous system

  • Stimulants increase the actions regulated by
    the nervous system
  • ex) ecstasy, Ritalin (when not used correctly)
  • Increase heart rate, blood pressure, and
  • Increase release of neurotransmitters at some
    synapses in the brain
  • This release leads to feeling of well-being
  • When these effects wear off the user quickly
    falls into fatigue and depression
  • Long term use can lead to circulatory problems,
    hallucinations, and psychological depression

How might someone behave if they have taken a
  • They might be fidgety and restless and eat very

  • Depressants decrease the rate of functions
    regulated by the brain
  • ex) Valium, Xanax
  • Lower blood pressure, slow heart rate, relax
    muscles, and relieve tension
  • Some depressants cause neurotransmitters to
    remain in receptors so impulses are not passed
    any more this causes parts of the brain that
    sense fear and pain to remain calm
  • User will become dependant to relieve
    anxietywhen depressants and alcohol are combined
    the results are usually fatal

How might someone behave if they have taken a
They might be slow moving and sleepy and speak
with a slur
Cocaine comes from the leaves of the cocoa
plant -causes sudden release in the brain of
neurotransmitter called dopamine -causes
ADDICTION an uncontrollable craving for more
of the drug -dopamine is normally released when
a basic need has been fulfilled (thirst,
hunger) -cocaine tricks the brain into releasing
large amounts of dopamine and produces intense
feelings of pleasure and satisfaction -when the
drug wears off the level of dopamine drops
sharply and the user feels sad and
depressed -strong psychological
dependence -powerful stimulant increases heart
rate, and blood pressure -some first time users
can have a heart attack and dieCrack is very
potent form of cocaine highly addictive after
one use
  • Opiates comes from flower called poppy ex)
    morphine, codeine, heroin
  • mimics chemicals in the brain known as
    endorphins, which normally help to overcome
    sensations of pain
  • initially they produce strong feelings of
    pleasure and security but the body adjusts to
    these high levels and then requires more
  • the body then cannot do without the drug
  • the user who stops taking these drugs will suffer
    from uncontrollable pain and sickness because the
    body cannot produce enough of the natural
  • Many users inject drugs for maximum effect and
    are at high risk of contracting HIV virus that
    causes AIDS

  • Hallucinogens drugs that cause hallucinations
  • Ex) PCP, angel dust, LSD, Psilocybin mushrooms,
    peyote cactus
  • profound distortions in a persons perceptions of
  • Under the influence of hallucinogens, people see
    images, hear sounds, and feel sensations that
    seem real but do not exist.
  • Some hallucinogens also produce rapid, intense
    emotional swings.
  • Affects serotonin receptors

  • Ecstasy - both a hallucinogenic and a stimulant
  • It makes users experience a rush of good feelings
    (a high) and makes someone's feelings much more
    intense, whether they're good or bad.
  • The drug's effects usually last up to 6 hours.
  • increases heart rate and can cause dry mouth,
    stomach cramps, blurred vision, chills, sweating,
    or nausea.
  • can make some users feel anxious, confused, and
    paranoid, like someone is trying to hurt them or
    is plotting against them.
  • Scientists have recently proven that Ecstasy
    causes direct damage to brain cells that are
    involved in thinking and memory.
  • can cause the salts and minerals in the blood to
    become dangerously diluted (thinned out), which
    can cause the brain to swell. Permanent brain
    damage can result.
  • If a person takes Ecstasy, his or her body can
    dangerously overheat during dancing or other
    physical activities, which can lead to death.

  • Marijuana comes from cannabis plant
  • active ingredient is THC (tetrahydrocannabnol)
  • causes temporary feeling of euphoria and
  • causes lung damage worse than smoking
  • long term use can result in memory loss,
    inability to concentrate, and reduced levels of
    testosterone in males

  • Alcohol one of the most dangerous and abused
  • acts as a depressant
  • slows reflexes, disrupts coordination, and
    impairs judgment
  • too much will cause user to not walk or talk
  • Of about 50,000 accidents 40 are alcohol
  • Women who are pregnant and drink run the risk of
    their child developing FETAL ALCOHOL SYNDROME
    (birth defects caused by the effects of alcohol
    on the fetus)
  • Disease called alcoholism users need to have
    a drink every day to function
  • Long-term use destroys cells in the liver and
    causes scarring called cirrhosis
  • Heavy drinkers may die from liver failure

DRUG ABUSE using a drug in any way that most
doctors could not approvePsychological
dependence mental craving, or need for the
drugPhysical dependence the body cannot
function without a constant supply of the drug
Which type of addiction do you think would be
harder to break psychological or physical?
What is the function of the endocrine system?
The endocrine system is made up of glands that
release their products into the bloodstream.
These products broadcast messages throughout the
body. The chemicals that broadcast messages
from the endocrine system are called hormones.
Nervous and Endocrine Systems
  • The endocrine system does the following
  • regulates metabolism
  • maintains salt, water, and nutrient balance in
    the blood
  • controls the bodys response to stress
  • regulates growth, development, and reproduction

  • Why are hormones needed?
  • chemical messages from one body part to cells in
    other parts of body
  • communication needed to coordinate whole body
  • maintaining homeostasis
  • energy production
  • growth
  • development
  • maturation
  • reproduction

growth hormones
Maintaining homeostasis
hormone 1
lowersbody condition
specific body condition
raisesbody condition
hormone 2
Endocrine System
  • Endocrine system releases hormones
  • glands which secrete chemical signals into blood
  • chemicals cause changes in other parts of body
  • slow, long-lasting response
  • growth hormones
  • sex hormones
  • response hormones
  • metabolism hormones
  • and more.

Regulation by chemical messengers
  • Neurotransmitters released by neurons
  • Hormones release by endocrine glands
  • Cells that have receptors for a particular
    hormone are called target cells. If a cell does
    not have receptors for a hormone, the hormone
    will have no effect on that cell.

endocrine gland
hormone carried by blood
receptor proteins
receptor proteins
target cell
  • Hormones are produced in special cells.
  • Often, these cells are part of an endocrine
  • Endo- means withinExo- means outside
  • An endocrine gland is an organ that produces and
    releases hormones directly into the bloodstream
    or into the fluid around cells.
  • Exocrine glands secrete hormones to the outside
    of the body they release through tube like
    structures called ducts

  • Pineal
  • melatonin
  • Pituitary
  • many hormones master gland
  • Thyroid
  • thyroxine
  • Adrenal
  • adrenaline
  • Pancreas
  • insulin, glucagon
  • Ovary
  • estrogen
  • Testes
  • testosterone

Body Regulation
  • Nervous system Endocrine system work together
  • hypothalamus
  • master nerve control center
  • receives information from nerves around body
    about internal conditions
  • communicates with pituitary gland
  • master gland
  • releases many hormones
  • sexual development, growth, milk production,

The thyroid gland has the major role in
regulating the bodys metabolism Hormones
produced by the thyroid gland and the parathyroid
glands maintain the level of calcium in the blood
The adrenal glands help the body prepare for
and deal with stress
Pancreas Insulin and glucagon released from the
pancreas help to keep the level of glucose in the
blood stable When the pancreas produces too
little insulin, a condition known as diabetes
mellitus occurs.
In diabetes mellitus, the amount of glucose in
the blood may rise so high that the kidneys
actually excrete glucose in the urine Very high
blood glucose levels can damage many organs and
tissues, including the coronary arteries.
Regulation of Blood Sugar
Endocrine System Control
body cells takeup sugar from blood
liver storessugar
blood sugar level (90mg/100ml)
liver releasessugar
  • The gonads serve two important functions the
    production of gametes and the secretion of sex
  • The female gonadsthe ovaries produce eggs
  • The male gonadsthe testes
  • (singular testis)produce sperm.

Sex Growth Hormones
  • Large scale body changes
  • how do they work
  • turn genes on
  • start new processes in the body by turning genes
    on that were lying dormant

Digestive and Excretory Systems
  • Digestive System
  • The digestive system converts food into nutrients
    that a bodys cells can use.
  • Some nutrients are used in metabolic reactions.
  • Other nutrients are used to build new cells.

What are the organs of the digestive system?
  • Mouth
  • Salivary glands
  • Pharynx
  • Esophagus
  • Stomach
  • Pancreas
  • Liver
  • Small intestine
  • Large intestine

Teeth mechanical digestion chewing the
foodSaliva contains AMYLASE enzyme that
breaks chemical bonds between the sugar monomers
in starchesEsophagus food tube that goes from
mouth to stomach
Can you swallow food if you are upside down? Why
or why not?
  • Yes, you can due to peristalsis
  • Peristalsis
  • Smooth muscle contractions of the esophagus that
    squeeze food through 25 cm to the stomach

  • Stomach food empties into this large muscular
  • Chemical digestion
  • Glands produce mucus, a fluid that lubricates and
    protects the stomach wall
  • Other glands produce hydrochloric acid, which
    makes the contents of the stomach very acidic.
    The acid activates an enzyme called pepsin, which
    is secreted by a third set of glands
  • Pepsin works best under the acidic conditions
    present in the stomach.
  • The combination of pepsin and hydrochloric acid
    begins the complex process of protein digestion.
    Pepsin breaks proteins into smaller polypeptide

  • Small Intestine
  • Duodenum first part of the small intestine
  • Chyme mixes with digestive fluids from the
    pancreas and liver
  • Most of the chemical digestion occurs here

  • PANCREAS sits just below the stomach
  • Produces hormones that regulate blood sugar
  • Produces enzymes that break down carbohydrates,
    proteins, lipids and nucleic acids
  • Produces sodium bicarbonate, a base that
    neutralizes stomach acids

  • LIVER large organ located just above the
  • Produces bile, a fluid loaded with lipids and
    salts it dissolves droplets of fat so enzymes
    can reach the fat molecules to break them down
  • Bile is stored in a small sac called the gall

  • Jejunum and ileum 2nd and 3rd parts of the
    small intestine
  • Absorbs the medium and small nutrients
  • VILLI - folded projection that increases the
    surface area of the walls of the small intestine

Cross Section of the Small Intestine
  • Large intestine removes water from undigested
    material that is left
  • Rich colonies of bacteria grow on the
  • undigested material left in the colon
  • These intestinal bacterial help the
  • digestive process.
  • Some of the bacteria produce
  • compounds that the body can use, such
  • as vitamin K.
  • The concentrated waste material that
  • remains after the water has been
  • removed passes through the rectum
  • and is eliminated from the body.

  • When something happens that interferes with the
    removal of water by the large intestine, you
    usually become aware of it right away. The
    condition that is produced is known as diarrhea.
  • The loss of salts and water due to diarrhea can
    be life threatening, especially for an infant.
    Diarrhea resulting from bacterial infections and
    contaminated drinking water is the leading cause
    of childhood death in many developing countries
    around the world.

Digestive and Excretory Systems
  • Digestion is the breaking down of large food
    molecules into smaller, more-usable ones.
  • Large food molecules must be broken down both
    physically and chemically.
  • The physical breakdown of food is called
    mechanical digestion.

Digestive and Excretory Systems
  • Mechanical digestion begins in the mouth, when
    food is chewed into small pieces.
  • As food is chewed, it mixes with saliva.
  • Saliva adds digestive enzymes to food, starting
    the process of chemical digestion.
  • Saliva also makes food particles easier to

Digestive and Excretory Systems
  • When food is swallowed, it enters the esophagus,
    a muscular tube that pushes food along with
    wavelike contractions.
  • Food is pushed into the stomach, where the
    digestion of protein begins.
  • Acid produced in the stomach kills bacteria and
    turns on enzymes that aid in chemical digestion.

Digestive and Excretory Systems
  • From the stomach, food is pushed into the small
  • Bile from the liver and enzymes made by the small
    intestine and pancreas complete digestion.
  • Proteins are reduced to amino acids.

Digestive and Excretory Systems
  • Complex carbohydrates are changed into simple
  • Lipids are changed to fatty acids and glycerol.
  • Nutrients can then be absorbed into the blood and
    lymph from the small intestine.

Digestive and Excretory Systems
  • Millions of tiny, fingerlike projections, called
    villi, line the small intestine.
  • The villi increase the small intestines surface
    area so most nutrients are absorbed by the time
    they reach the large intestine.

Digestive and Excretory Systems
  • Excretory System
  • The human body must remove wastes that are
    produced by metabolism in a process known as
  • Excretion enables the body to maintain its
    osmotic and pH balance.
  • Sweat, exhaled carbon dioxide, and urine are all
    eliminated through excretion.

Digestive and Excretory Systems
  • The kidneys are the primary organs of excretion.
  • You have two
  • Located on either side of the spinal column near
    the lower back
  • They are the size of a fist
  • Each kidney is composed of nearly one million
    microscopic filtration units called nephrons.
  • At the end of the nephron is the Bowmans
    capsule, a cup-shaped structure.

Digestive and Excretory Systems
  • As blood flows through capillaries in the
    capsule, blood pressure forces fluid out of the
    capillaries into the capsule.
  • This fluid contains water, salt, glucose, amino
    acids, urea, and other substances.
  • Urea is a nitrogen-containing waste product that
    is released into the blood by the liver.

Digestive and Excretory Systems
  • The fluid passes into a narrow tubule, which is
    surrounded by capillaries.
  • There, glucose and some other useful molecules in
    the fluid reenter the bloodstream.
  • The remaining fluid passes out of the nephron
    through collecting ducts, where much of the water
    is removed.

Human Kidney Structure
Digestive and Excretory Systems
  • Waste solution from the kidneys is called urine.
  • Urine flows from the kidneys through a ureter to
    the urinary bladder.
  • Urine is collected and stored in the bladder.
  • When the bladders muscular walls contract, urine
    exits through the urethra.

Excretory System in the Human Body
Respiratory and Circulatory Systems
  • What are the structures of the respiratory
  • PHARYNX passageway for both air and food
  • TRACHEA air moves through aka windpipe
  • LARYNX contains two highly elastic folds of
    tissue called vocal cords when air passes the
    folds vibrate to produce sound
  • BRONCHI after the trachea there are two
    passageways they lead to the lungs
  • BRONCHIOLES smaller branches after the bronchi
  • ALVEOLI tiny air sacs where gas exchange
    occurs. Surrounding the alveoli are capillaries
    where the respiratory and circulatory systems
  • DIAPHRAGM flat muscle at bottom of chest cavity
    that helps with breathing

  • NOSE
  • NICE
  • LIKE
  • TO
  • BLUE
  • AIR

Respiratory and Circulatory Systems
  • Respiratory System
  • The respiratory system brings oxygen, O2, into
    the body.
  • It also carries carbon dioxide, CO2, a waste
    product of cellular respiration, out of the body.
  • Air enters the respiratory system when you inhale
    through your nose or mouth.

Respiratory and Circulatory Systems
  • Inhalation occurs when muscles around the chest
    area contract and expand the rib cage.
  • Inhaled air passes through a series of tubes to
    reach the lungs.
  • Within each lung, the tubes carrying the air
    split into smaller and smaller tubes, called

Respiratory and Circulatory Systems
  • The smallest bronchioles end in groups of tiny
    air sacs called alveoli (singular, alveolus),
    which are surrounded by blood vessels.
  • Exchange of gases by diffusion takes place across
    the thin, moist membranes of the alveoli.
  • Oxygen leaves the alveoli and enters the blood,
    while CO2 leaves the blood and enters the

Trace the path of an oxygen molecule through the
human body
  • Parts of the Human Respiratory System

Respiratory and Circulatory Systems
  • Circulatory System
  • The circulatory system carries nutrients, oxygen,
    hormones, and wastes through the body and
    distributes heat to maintain homeostasis.
  • The cardiovascular system and the lymphatic
    system make up the bodys circulatory system.
  • Blood, blood vessels and the heart make up the
    cardiovascular system.

Respiratory and Circulatory Systems
  • Arteries carry blood to capillaries.
  • A capillary has an extremely thin wall that
    allows gases and nutrients in the blood to
    diffuse across it into fluid around body cells.
  • From the capillaries, blood enters the veins,
    which return blood to the heart.

  • As you can feel with your hand, your heart is
    located near the center of your chest
  • The heart, which is composed almost entirely of
    muscle, is a hollow organ that is about the size
    of your clenched fist
  • The heart is enclosed in a protective sac of
    tissue called the pericardium
  • In the walls of the heart, there are two thin
    layers of epithelial and connective tissue that
    form a sandwich around a thick layer of muscle
    called the MYOCARDIUM. The powerful contractions
    of the myocardium pump blood through the
    circulatory system
  • There is a right side and a left side to the
    heart they are separated by the septum (wall)
    which prevents the mixture of oxygen-rich and
    oxygen-poor blood
  • Atrium (atria is plural) two of these upper
    chambers receives the blood
  • Ventricle two of these lower chambers pump
    blood out of heart

What is pulmonary circulation?
  • Occurs on the right side of the heart
  • Blood is pumped from the heart to the lungs and
    back to the heart again
  • Why would your blood get pumped to the lungs and
    then back to the heart?
  • Oxygen poor blood goes to the lungs to get rid of
    carbon dioxide and pick up oxygen
  • The oxygen rich blood then has to go back to the
    heart to get pumped to the rest of the body

What is systemic circulation?
  • Occurs on the left side of the heart
  • Oxygen rich blood from the lungs gets pumped
    throughout the rest of the body and back to the
    heart now the blood is oxygen poor and must go
    to the lungs to dump the carbon dioxide

(No Transcript)
What makes your heart beat?
  • There are two networks of muscle fibers in the
    heart, one in the atria and one in the ventricles
  • When a single fiber in either network is
    stimulated, all the fibers are stimulated and
    the network contracts as a unit
  • Each contraction begins in a small group of
    cardiac muscle cells located in the right
    atriumthe sinoatrial node
  • Because these cells set the pace for the heart
    as a whole, they are also called the pacemaker

What determines if your heart beats fast or slow?
Your heart can beat faster or more slowly,
depending on your bodys need for oxygen-rich
blood. In times of stress, does the heart beat
faster or slower? It beats faster
Respiratory and Circulatory Systems
  • This system acts like a network of highways that
    transports materials to and from the bodys
  • The network is made up of three kinds of vessels
    arteries, capillaries, and veins.
  • Arteries have thick, muscular walls to withstand
    the force of the blood pumped out of the heart.
  • Veins have thinner walls with valves to prevent
    the blood from back flowing.
  • Capillaries are the smallest vessel where the
    exchange of gasses, nutrients and wastes take

Circulation Pathway in the Human Body
Respiratory and Circulatory Systems
  • Blood moves through blood vessels and interacts
    with every body system.
  • Blood brings materials that the body system needs
    and carries away the products that the system
  • Blood also carries waste away from the system.

What is blood made up of?
  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
  • Clotting proteins

Respiratory and Circulatory Systems
  • About 45 of blood is cells and cell fragments.
    The remaining 55 is plasma, the liquid portion
    of blood.
  • Plasma is a solution made of about 90 water and
    10 solutes. The solutes include nutrients,
    wastes, and salts.
  • Salts have many functions, including maintaining
    osmotic balance with the fluids inside of cells
    and regulating blood pH.

  • aka erythrocytes transport oxygen
  • They get their color from HEMOGLOBIN
    iron-containing protein that binds to oxygen in
    the lungs and transports it throughout the body
    where oxygen gets released
  • Shaped like discs
  • Made in the bone marrow
  • Mature red blood cells do not have nuclei
  • Live for 120 days and then destroyed on liver and

WHITE BLOOD CELLSaka leukocytes attack
foreign substances or organisms
  • Produced in red bone marrow
  • Some live for months others only a few days
  • PHAGOCYTES eating cells engulf and digest
    foreign cells
  • Some slip across capillary walls and attack
    invading organisms
  • Others release chemicals that help the body fight

Platelets and blood clottingWe dont want to
lose our blood
  • How does bleeding stop?
  • We have the ability to form clots
  • Blood clotting is made possible by plasma
    proteins and cell fragments called PLATELETS -
    Cell fragments released by bone marrow
  • When platelets come into contact with a wound
    they become sticky and other platelets start to
  • They release proteins called clotting factors
    that cause other types of proteins to form a mesh
    over the wound this is called a clot

Respiratory and Circulatory Systems
  • Besides carrying materials, blood distributes
    body heat to help the body maintain a steady
  • When the body is warm, blood vessels in the skin
    widen, allowing heat to leave the body.
  • Blood vessels narrow when the body is cold. This
    helps the body to divert blood to deeper tissues
    and conserve heat.

Blood Pressure
  • When the heart contracts, it produces a wave
    of fluid pressure in the arteries.
  • The force of the blood on the arteries walls
    is known as
  • blood pressure.
  • Blood pressure decreases when the heart
    relaxes, but the system still remains under
  • Every time the heart pumps, some fluid from
    the blood is forced out of the capillaries.

Respiratory and Circulatory Systems
  • The escaped fluid collects in spaces around body
  • This fluid, called lymph, is picked up by the
    lymphatic system and returned to the blood.

Respiratory and Circulatory Systems
  • The lymphatic system is made up of a network of
    vessels, tiny bean-shaped structures called lymph
    nodes, and lymph tissue.
  • Lymph vessels collect lymph and return it to two
    large veins in the neck.
  • As lymph moves through lymph vessels, the fluid
    passes through lymph nodes, where white blood
    cells collect.

Respiratory and Circulatory Systems
  • The white blood cells destroy bacteria and other
    dangerous material in the lymph.
  • In this way, the lymphatic system helps the body
    fight infection.

  • Lymph Movement

Key Ideas
  • How do the skeletal and muscular systems help the
    body maintain homeostasis?
  • The skeletal and muscular systems enable movement
    and provide support and protection for tissues
    and organs.

Key Ideas
  • How does the integumentary system help the body
    maintain homeostasis?
  • The integumentary system protects the body from
    injury and UV radiation, defends against disease,
    helps regulate body temperature, and prevents the
    body from drying out.

Key Ideas
  • How do the nervous and endocrine systems help the
    body maintain homeostasis?
  • The nervous system collects and responds to
    information about the bodys internal and
    external environment.
  • The endocrine system regulates metabolism
    maintains salt, water, and nutrient balance in
    the blood and regulates growth, development, and

Key Ideas
  • How do the digestive and excretory systems help
    the body maintain homeostasis?
  • The digestive system converts nutrients that a
    bodys cells can use.
  • Excretion enables the body to maintain its
    osmotic and pH balance.

Key Ideas
  • How do the circulatory and respiratory systems
    help the body maintain homeostasis?
  • The respiratory system brings oxygen, O2, into
    the body and carries carbon dioxide, CO2, out of
    the body.
  • The circulatory system carries nutrients, oxygen,
    hormones, and wastes through the body and
    distributes heat to maintain homeostasis.

Feedback Mechanisms
  • Write a short explanation of how you think a
    thermostat on a furnace helps to keep the room
    temperature at a comfortable level.
  • Answer the following question
  • How does the human body act like a thermostat?

Key Ideas
  • How do feedback mechanisms help maintain
  • How does a feedback mechanism control a persons
    breathing rate?
  • How does a feedback mechanism maintain the
    concentration of glucose in the bloodstream?

Mechanisms of Control
  • A bodys internal state varies around a certain
    average value
  • Homeostasis maintains a dynamic equilibrium in
    the body.

Mechanisms of Control
  • Your body has a variety of feedback mechanisms
    that detect deviations in the bodys internal
    environment and make corrections.
  • A feedback mechanism is a mechanism in which the
    last step in a series of events controls the
    first step.

Negative Feedback
  • Negative feedback
  • every time body is high or low from normal level
    a signal tells the body to make changes that will
    bring body back
  • body temperature
  • control of blood sugar

  • Comparing Positive and Negative Feedback

Mechanisms of Control
  • Positive feedback, a change in the body causes
    even more change in the same direction.
  • Positive feedback occurs in blood clotting.
  • One clotting factor activates another in a
    cascade that leads quickly to the formation of a
  • Another example of positive feedback occurs in
    females, when rising levels of estrogen cause
    another hormone to be secreted until an egg is
    released from an ovary.

  • Blood and the Transport of Carbon Dioxide

Controlling Blood-Glucose Level
  • Your bodys cells need glucose to perform
    cellular respiration.
  • When you digest a large meal, a large amount of
    glucose is introduced into your body in a short
    period of time.
  • Two hormones, insulin and glucagon, control the
    level of glucose in the bloodstream.

Controlling Blood-Glucose Level
  • Insulin and glucagon are released by the
  • These
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