Review! Vocabulary
The tendency of an organism to
maintain a stable, constant internal
environment
homeostasis
The body’s internal temperature.
Core temperature
The body’s external temperature.
surface temperature
A specialized porous structure in the leaf
of a plant that helps it achieve internal
balance.
stomata
Specialized cells of the nervous system which
relay signals to the spinal cord and brain.
Sensory Neurons
An involuntary response that happens
internally.
Physiological Response
A response that is outwardly observed that
is consciously controlled.
Behavioral Response
A response that is outwardly observed that
is NOT consciously controlled.
Reflex
This system is made up of the brain, the spinal
cord, and the nerves that are found throughout
the body and regulates automatic responses.
Nervous System
A type of cell in the nervous system that
produces, sends, and receives signals.
Neurons
A type of nerve cell that protects,
supports, and insulate neurons.
Glial Cells
A specialized part of the brain that is part of the
nervous and endocrine system and regulates
physiological processes like water balance, body
temperature, feeding, and sleep.
Hypothalamus
A body system made up of glands that
releases hormones.
Endocrine System
Chemical messengers that travel through
the bloodstream.
Hormones
Proteins that fit the shape of a hormone
similar to a “lock and key.” Once the
hormone is bound, the cell is ready to
respond.
Receptors
A hormone released from the pituitary gland
during dehydration causing kidneys to reabsorb
more water and less water to be excreted in
urine.
Vasopressin
A gland that is part of the hypothalamus
and releases vasopressin
Pituitary Gland
A system that keeps automatic responses
from vastly changing internal conditions.
Feedback Systems
A system that shuts off a response that the
body originally had because it was out of
balance.
i.e. water balance and hypothalamus stops releasing
vasopressin
Negative Feedback
A feedback system that adjusts internal
conditions towards the initial condition.
i.e. Blood clot, so you send more clotting fibers to
reduce blood loss.
Positive Feedback
How does the endocrine system and the nervous
system each contribute to maintaining homeostasis?
• The nervous system senses the outside environment
and initiates a series of reactions in the body to allow
the body to respond. The endocrine contributes to
homeostasis by producing hormones or chemical
messengers that carry out a process that helps restore
balance in the body.
Explain the role that sensory neurons play in the
maintenance of homeostasis in the human body.
• Sensory neurons receive signals and trigger the brain
to respond to external stimuli.
Describe the general way that feedback systems work to
adjust internal conditions in response to change.
• A positive feedback system adjusts the body
internally towards an initial condition.
Oxytocin/child birth is positive feedback.
Describe the general way that feedback systems work to
adjust internal conditions in response to change.
• A negative feedback system stops the response that
the body had to being out of equilibrium. For
example, when one goes from dehydrated to
hydrated vasopressin causes the kidneys to absorb
more water. Once the person is hydrated, negative
feedback tells the hypothalamus to stop producing
vasopressin..