Download Homeostasis- maintaining stable, constant internal environments

Homeostasis- maintaining stable, constant
internal environments
• 2 things are required for homeostasis• 1- organism must be able to sense when changes
have taken place in the external and internal
environments
• 2- must be able to respond with appropriate
adjustments to keep internal environment
stable.
How humans sense things- Ex Heat
Sensory Neurons in the skin – send
information to the spinal cord
which sends it to the brain.
The brain interprets this signal
Brain returns direction signal
through Motor Neurons which
generate the movement- aka
moving the finger away from the
flame.
The Nervous System
• Brain and a network of
nerves
• In charge of
involuntary
(automatic) and
voluntary responses
Cells of the Nervous System
• Neurons- produce, send
and receive signals
• Glial cells- protect,
support and insulate
neurons
Parts of the Brain
• Brain stem- Directs
critical involuntary
(automatic) responses
necessary for life
• Ex- heart rate and
breathing
Parts of the brain
• Cerebellum- balance
and posture
• Cerebrum- conscious
though, language,
voluntary movement
Parts of the Brain
• Hypothalamusregulates physiological
processes important to
homeostasis
• Ex- water balance, body
temperature, feeding
and sleep
• Also part of the
Endocrine system
Endocrine System
• In charge of hormones
– “chemical
messengers”
• Hormones play a large
role in homeostasis
• Ex- regulate sugar
balance
Hormones
• Travel through the
blood
• Only work on cells that
have that specific
hormone’s receptor
• Receptors- proteins on
the cell membrane
that are shaped to fit
the hormone.
How it works- Dehydration
• 1- Sensory Neurons detect water • 4- The receptors simulate
shortage due to amount of
the kidney cells to reabsorb
sodium in the blood
water
• 2- Neurons in the Hypothalamus
simulate the release of a
• At the same time the
hormone Vasopression from the
Endocrine systems is
Pituitary gland
working the nervous system
• 3- Hormone travels through the
can also trigger thirst.
blood until it hits the kidney cells
Then what?
• How does the body know when to stop producing Vasopressin?
• Feedback systems are established through out the body
• 2 types of feedback systems
Negative Feedback
• Body uses this system to
shut off the response the
body has started
• Ex- once the water
balance has been
regained the body signals
the hypothalamus to
reduce the release of
Vasopressin
Positive Feedback
• Adjusts internal conditions
towards initial conditionaka it makes initial change
keep happening till its
complete
• Ex- Small clot forms due to
bleeding positive feedback
causes more clotting factors
to build up increasing the
blood clot size