The Need for Homeostasis

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The Need for Homeostasis

• In this chapter we will learn how organisms have
  adapted to maintain a stable internal
  environment, even though the environment around
  them is constantly changing. As organisms
  increase in size, their ability to remain
  stable . Fluid surrounds the cells in a
  multicellular organisms and this fluid is called
  (ICF). It is the ICF that remains
  stable even though conditions outside the
  organisms are changing. Small changes in this
  fluid result in for the organism.

increases
intercellular fluid
death
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homeostasis

• ______________- maintaining a constant internal
  environment (staying the same)
• dynamic equilibrium- the way a body makes slight
  adjustments to change so the internal environment
  will

stay the same
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• Thermoregulation- maintaining a fairly constant
• - can do this
• - hypothalamus- a structure in the brain that
  has thermoreceptors that detect

internal temperature
Birds mammals
temperature change
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• How animals regulate their temperature
• - if blood cools a little the hypothalamus
  sends signals to the blood vessels near the skin
  to so that less blood will flow
  through them and they will
• - if a body is still losing heat on a really
  cold day, starts which makes your muscles burn
  food and
• -when body temperature increases, the
  hypothalamus sends a message to the blood vessels
  to and let more blood

become narrower
lose less heat
shivering
produce energy
expand
give off heat to the air
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• - dogs pant water evaporates from these
• - people perspire surfaces
• - __________________- one change produces
  another change, which in turn reverses the
  initial change.
• - hot body? sweats ? cools body
• 1. sensor- (detects change)
• - (one of the senses)
• 2. control unit- (thermostat)-
• 3. effector- (takes instructions from control
  unit)
• -
• - positive feedback- causes a change to occur
• - injury to blood vessel? causes proteins to
  clot? causes more proteins to clot? bleeding
  stops

taking heat away with it
negative feedback
skin
hypothalamus
muscles of blood vessels, shivering muscles,
sweat glands
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• B. Water Balance
• - plants
• 1. stomates allow gases in and out but they
  also
• 2. guard cells have a curved shape when full of
  water but if they lose water their shape
  becomes less curved and they
• 3. water loss is
• 4. if more water returns to the guard cells,
  they become curved again which

lose water
close the stomate
reduced
opens the stomates
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• C. Breathing Rates
• 1. CO2 levels in the blood increase and cause
  the blood to become more
• 2. receptors in the body detect this change in
  pH (acidity)
• - receptors are in
• 3. information is sent to the
• of the brain
• 4. medulla send information to
• - controls how
• - controls how
• - controls how
• negative feedback- high CO2?
• breathe more? lowers CO2

acidic
aorta, carotid arteries, brain
medula
adjust breathing
rapidly we breathe
deeply we inhale
quickly our heart beats
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• D. Systems for Maintaining Homeostasis
• 1. - regulates body fluids (removes
• harmful wastes)
• 2. - produces hormones (chemical
• messengers)
• 3. - defends the body

Excretory system
Endocrine system
Immune system
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Integration and Control Nervous and Hormone
Regulation

• To maintain homeostasis, organisms must have
  means for integration (all body parts work
  together) and means for control (acting in an
  organized and appropriate way.) Two organ
  systems are responsible
• ________________ and _______________
• The two systems work together based on chemical
  communication between the cells.
• ___________- involves receiving information from
  the environment, processing that information,
  and responding to it.
• - involves the communication of an
  organism with its environment and within its
  own body among all its parts.

Nervous
Endocrine
Regulation
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• A. Nervous Regulation-
• Neurons-
• - specialized to carry (nerve impulses)
• - receive, conduct, and send impulses
• - __________- receives messages
• - __________- (cyton)- contains nucleus
• - between the dendrite and the
  axon
• - __________- carries impulses away from
  cell body toward the next cell
• - ends in a series of terminal
  branches

rapid
nerve cells
messages
dendrites
cell body
axon
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impulse

• - __________ is a change in electricity
  caused by the rapid movement of Na and K
  ions across the cell membrane

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• Synapse-
• - impulse is carried across this space
  by special chemicals called
  ___________________.
• Neurotransmitters- released by the terminal
  branches (axon) of one neuron and
• to the dendrite of the next neuron
• - examples (at least 30 types) are
  acetylcholine and norepinephrine

space between two nerve cells
neurotransmitters
diffuse across the synapse
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Communication 1. __________- condition or
change in the environment that is
detected by one of your senses
(receptors) 2. __________- the way an organism
reacts to a stimulus using its muscles or
glands (effectors)
stimulus
eyes, ears, antennae, etc.
response
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• Communication in Animals
• 1. jellyfish- - nerves are distributed
  equally in all directions
• - if a jellyfish is touched, it
  sends the message throughout its body
  and then changes its shape or
  direction of movement
• -

nerve net
have no brain and cannot learn
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nerve net

• 2. sea star- each arm has a
• - one main nerve from each arm connects
  the nerve net to the central
• 3. planaria- (flatworm)- two parallel nerve
  cords that run along the
  length of the body
• - nerve cords meet a cluster of nerves
  at the head ( )
• - central nervous system (CNS)-
• - peripheral nervous system (PNS)-

nerve ring
brain
nerve cords and the brain
all the other nerves
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• 4. earthworm- CNS- double nerve cord that runs
  along its underside (
  )
• - cluster of neurons in
  each segment
• - brain at the head (
  )
• - PNS- nerves that extend from nerve
  clusters to the rest of the body

ventral side
anterior
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• 5. crayfish- double ventral nerve cord
• - brain
• - clusters of nerves (ganglia) along the
  nerve cord that control the appendages
• - sensory receptors- structures designed
  to receive sensory info.
• -

antennae, eyes, sensory bristles
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• 6. vertebrates- CNS-
  (dorsal) made of interneurons
• PNS- connects the CNS to all parts of
  the body
• - ______________- carry
  impulses from CNS to effectors
• - ______________- carry impulses
  from senses to CNS
• - interneurons (associative)- send
  messages between the above
  two

brain spinal cord
motor neurons
sensory neurons
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• Diseases of the Nervous System
• 1. _______________- occurs when someone
  experiences brain damage just before or after
  birth
• - affects motor function (movement)
• 2. _______________- slow deterioration of
  myelin (fatty substance that covers axons)
• - shaking, blurred vision, slurred speech
• 3. ________________- inability to think, speak,
  care for oneself as you get older memory loss
• 4. _________________- neurons in the brain that
  produce dopamine lose function
• - shaking, poor balance, stiffening

Cerebral palsy
Multiple sclerosis
Alzheimers disease
Parkinsons disease
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• B. Endocrine Regulation
• - endocrine system- system of that help
  maintain homeostasis
• 1. Plants- _______- cause plants to grow faster
  where they are concentrated
• - cause plants to bend toward the
  light
• - development of fruit
• 2. Arthropods- animals with hard external
  skeletons and appendages with joints
• -
• - hormones- shed their skin
• - hormone- keep insect in larval form,
  when the hormone level drops the larva
  turns to a pupa and then an adult
• 3. Frogs- is controlled by hormones

glands hormones
Auxins
insects, spiders, crabs, etc.
molting
juvenile
metamorphosis
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• C. Types of Hormones
• 1. steroid hormones- formed from cholesterol
• - sex hormones
• 2. protein hormones- example is insulin

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• D. Human Endocrine System
• 1. ____________- part of the brain that
  receives information from nerves and by
  monitoring the blood
• - controls the
• 2. pituitary gland- master gland
• - controls
• a. anterior pituitary- produces six hormones
• b. posterior pituitary- produces two hormones
• 3. adrenal gland- on top of kidney
• 4. thyroid- neck
• 5. parathyroids- connected to the thyroid
• 6. pancreas- produces insulin which
• 7. ovaries or testes

hypothalamus
pituitary gland
many other glands
controls glucose levels in the blood
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• E. Diseases of the Endocrine System
• 1. _______- disease of the thyroid gland caused
  by a lack of iodine which is needed to make
  the hormone thyroxin
• - swollen neck, slow metabolism
• 2. _______________- the thyroid releases too
  much hormone
• - fast metabolism
• 3. dwarfism- body is much smaller than normal
• - can result from too little being
  produced by the anterior pituitary gland
• 4. diabetes- pancreas doesnt produce enough
• - if not treated can cause damage to eyes,
  kidneys, heart, arms legs

Goiter
Graves disease
growth hormone
insulin
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Goiter
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Graves Disease
Marty Feldman
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Dwarfism
Little People Big World