Chapter 3 - Homeostatic Regulation: Normal Function and Stress Responses Flashcards
The book divides homeostatic regulation into five layers beginning at the lower levels in the system. Can you name them?
- Organs and their local reflexes
- Autonomic and endocrine messengers
- Brainstem regulation
- Hypothalamic regulation
- Inputs from higher brain centers
The primary hypothalamic nucleus that regulates endocrine and autonomic components of the fight-or-flight response during stress is the …
paraventricular nucleus (PVN)
How can the neurosecretory cells of the PVN react to hormones?
The PVN is in contact with the third ventricle.
Two stress-related peptides secreted by the hypothalamus to stimulate the pituitary are …
- Corticotropin-releasing factor (CRF)
2. Arginine vasopressin (AVP).
At the anterior pituitary, AVP and CRF cause the secretion of …
adrenocoricotriopic hormone (ACTH) and beta-endorphin.
ACTH reaches which target in the body?
ACTH reaches the adrenal cortex.
ACTH reaches the adrenal cortex and causes…
causes an increased rate of synthesis and release of cortisol.
HPA.
Hypothalamic-pituitary-adrenocortical axis.
The endocrine response during stress has two parallel arms. Which?
- The adrenoocortical response
2. The adrenomedullary response
The adrenal medulla is activated by …
The adrenal medulla is activated by sympathetic preganglionic fibers.
The adrenal medulla is activated by sympathetic preganglionic fibers originating in …
The adrenal medulla is activated by sympathetic preganglionic fibers originating in the brainstem nucleus of the solitary tract of the spinal cord.
During states of stress, the adrenal medulla secretes …
During states of stress, the adrenal medulla secretes epinephrine and norepinephrine into the circulation.
In general, the action of epinephrine …
In general, the action of epinephrine reinforces the actions of the sympathetic nerves.
What seems to be the role of norepinephrine during stress responses?
Although norepinephrine also enters the bloodstream from the adrenal gland, its actions on target tissues are negligible.
Unlike epinephrine, which acts mainly during states of stress, cortisol functions to …
Unlike epinephrine, which acts mainly during states of stress, cortisol functions to maintain homeostasis during normal states of activity and also during periods of stress.
What happens to animals deprived of their adrenal cortex (where cortisol is synthesized)?
They’re difficult to keep alive.
Addison’s disease causes an insufficiency of adrenal function. What are the symptoms?
Poor salt and water balance, low blood pressure, and other forms of autonomic dysfunction.
In the absence of cortisol, epinephrine would be less effective at its target tissues. Why?
Cortisol is necessary for the normal synthesis and function of both alpha and beta-adrenoreceptors.
What is cortisol’s diurnal rhythm?
Cortisol secretion shows a very pronounced diurnal rhythm that is integral to its functioning in homeostasis. Cortisol output reaches a peak before awakening, usually about 6:00 a.m. in normal sleepers, and its levels drop slowly until about noon, when a small rise occurs during the midday meal. Cortisol levels vary over the afternoon hours and then decline to a low point during sleep in the early morning hours.
How does cortisol affect the hippocampus?
The hippocampus is recognized as the primary site of cortisol’s negative feedback. When cortisol is absent, tonic activity in the hippocampus stimulates the PVN, causing it to release high levels of CRF. When cortisol levels are high, this tonic activity is depressed in the hippocampus.
Experimental animals deprive of the adrenal cortex react how during stress?
Because of cortisol’s essential regulatory functions, animals who lack the hormone are prone to death during periods of stress. It is an indication that cortisol during acute stress serves to prevent an overactive stress response from threatening the homeostasis of the individual.
