Hypothalamus/ Ant and Post Pituitary Flashcards
Types of Secretory Patterns
- Circadian (diurnal) Rhythm
- Ultradian Rhythm
- Stimulus Induced
- Longer time interval Rhythms
What is the most common example of a circadian rhythm hormone?
Cortisol
- ACTH stimulates cortisol release so it also has a circadian rhythm
What is an ultradian rhythm and what is an example?
An Ultradian rhythm is one that occurs multiple times each day.
LH (leutenizing Hormone) release is an example
Three methods of controlling plasma hormone concentrations?
1) Increases or decrease secretion rate
2) Increase or decrease the level of hormone biding protein for that particular hormone
3) Increase or decrease degradation rate
Positive feedback
The endocrine system’s response to a stimulus reinforces that stimulus.
Ex: stretch of the cervix stimulates oxytocin release, this leads to more stretch of the cervix
Negative feedback
The endocrine system’s response to a stimulus is to reduce that stimulus
Describe the negative feedback mechanism associated with a rise in plasma glucose
Plasma glucose ^^ –> Rise in Insulin secretion–> Inc concentration of insulin in the plasma –> Rise in glucose uptake and utilization by the muscle and adipose tissue –> plasma glucose slowly goes back down to normal
So…how does the plasma glucose level keep from dropping too far below normal?
As Plasma Glucose Goes down –> GLUCAGON is secreted –> Hepatic Glucose is released –> Plasma glucose concentration comes back to normal.
How do hormones move from the top region of the pituitary gland to the bottom?
Axoplasmic flow…takes about a week for them to move this short distance.
How does hormone get stimulated to start the movement down the center of the pituitary?
Action potential
Where is the Pituitary gland located
base of brain in a bony pocket called the Sella turcica
What connects the pituitary to the base of the brain?
Infundibulum…this contains the nerves and veins
What are the two posterior pituitary gland hormones?
ADH and OT (oxytocin)
The posterior pituitary is basically a neural extension of the hypothalamus…where do the nerve axons come from?
Mainly from two nuclei in the hypothalamus: the Supraoptic nucleus (SON) and the Paraventricular Nucleus (PVN). The axon terminals are located near capillaries in the posterior pituitary and release their hormones here.
The area where hormones are released in the posterior pituitary is called?
Pars Nervosa
What is the function of Oxytocin…KNOW
stimulates contraction of the uterus and myoepithelial cells in the mammary gland (pushes out breastmilk)
WHat is the function of ADH,,,KNOW
regulates retention of water by increasing water channels in the walls of the kidney.
Also increases the contractility of vascular smooth muscle…Pressor effectM
REMEMBER: Oxytocin and Vasopressin have slightly overlapping activity