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Careful Coordination
• Vocabulary words
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Nervous system
Neurons
Glial cells
Hypothalamus
Physiological
processes
– Endocrine
– Endocrine system
– Hormones
Vocabulary words
-- Receptors
– Vasopressin
– Pituitary gland
– Feedback Negative
feedback
– Blood pressure
– Constrict
– Positive feedback
Careful Coordination
• Nervous system
– The nervous system regulates many
automatic responses.
– The nervous system is responsible for all of
the body’s voluntary responses also.
– The nervous system is made up of all the
nervous tissue, the brain, and spinal column.
– The nervous system plays a key role in
coordinating internal balance.
• The nervous system contains two types of cells
– Neurons produce and send nerve impulses
– Glial cells protect, support and insulate neurons
– Brain is the control center for the nervous system.
• The brainstem directs the critical, automatic
responses necessary to sustain life.
• Hypothalamus is a specialized part of the brain
that regulates a variety of physiological processes..
– Water balance, body temperature, feeding and
sleep as well as help to regulate several
endocrine functions
• Endocrine system
– Made up of glands and cells that produce and release
chemical messengers called hormones, directly into
the blood
– Many hormones work to regulate internal balances
like water and blood sugar balance.
– Hormones are carried by the blood past every cell of
the body but only “target” cells and organs are able to
respond to a specific hormone.
– The “target” cells have a receptor (protein that fit the
shape of a specific hormone molecule) on their
membrane (like a lock “target cell receptor” and key
“hormone”)
•
Example of how the nervous system and the
endocrine system work together to maintain
homeostasis.
– Hormones control a variety of processes by binding
to target cell receptors. We will use dehydration as
our example.
1. Sensors in the hypothalamus detect the increase in
sodium ion concentration in the blood. (remember
dehydration causes this increase in sodium ion
concentration).
2. Specialized neurons in the hypothalamus, which
extend into the pituitary gland, respond to the
increase in sodium concentration by causing the
pituitary gland to produce and release a hormone
called vasopressin.
3. Vasopressin is a hormone that is carried
throughout the body in the blood.
4. The target cells for vasopressin are the cells
of the kidney.
5. The vasopressin causes the membranes of
the kidneys’ tubules to become more
permeable to water.
6. This means more water can be reabsorbed
into the blood and less water is secreted to
the urine.
7. The result is prevention of further
dehydration.
Example of how the nervous system and the endocrine
system work together to maintain homeostasis.
• At the same time, the nervous system also works to
restore water balance.
• Parts of the nervous system sense the increase in
sodium ion concentration and respond by triggering
thirst.
• Homeostasis involves the coordination of many body
systems and a combination of automatic responses
(physiological responses) and voluntary behaviors
(behavioral responses).
• The body uses feedback systems to maintain an internal
balance ad to regulate responses to changing conditions
– Negative feedback systems work to shut offthe
response that the body had to being out of balance
• When the body senses dehydration it responds by
producing more vasopressin and reabsorbing
more water.
• When the body senses that the amount of water in
the body is at the appropriate level, it signals the
hypothalamus to reduce that amount of
vasopressin that is released into the blood.