Lec 9 Flashcards
What are three important points about hormones?
- Hormones act in gradual fashion
- Hormones often have pulsatile secretion-in bursts
- Some hormones are controlled by circadian clocks
What are the four details of neural?
- Millimeters
- Milliseconds
- Precise
- All or none
What are the four details of hormonal?
- Up to meters
- Minutes/hours/days
- Diffuse
- Graded
What is the process of the endocrine feedback loop?
Starts at the hypothalamus releasing TRH getting to the Anterior pituitary which changed it to TSH which then gets to the Thyroid gland which releases thyroid hormones which reach target cells. The TSH goes back when it’s enough.
In the endocrine feedback loops there are 2 hormones, what are they?
- Tropic hormones: pituitary hormones that affect other endocrine glands (TRH)
- Releasing hormones: from hypothalamus control pituitary’s release of tropic hormones
What two hormones does the posterior pituitary secrete?
- Vasopressin (antidiuretic hormone (ADH)) raises blood pressure and inhibits urine formation. DIRECT SIGNAL
- Oxytocin- Maternal behavior/bonding
What is goiter?
Goiter is swelling of the thyroid gland from iodine deficiency.
What does the thyroid hormone contain thats important?
It contain iodine and depends on its supply.
What is Cushing’s disease?
Results from long-term excess glucocorticoids, with fatigue and depression.
What is negative feedback?
Negative feedback systems are the main homeostatic mechanisms if a desired set point is deviated from, compensatory action begins.
Homeostasis helps derive physiological motivation.
What is the major control of homeostasis? What is the preoptic area?
Hypothalamus
Preoptic areas: the thermostat of the brain
What is hypovolemic thirst? What does it cause release of?
Is stimulated by low extracellular/intravascular volume.
Triggered by LOSS OF WATER VOLUME
Baroreceptors in blood vessels and heart detect the initial drop. Brain activated thirst and salt craving and arteries constrict to raise BP.
Causes release of Vasopressin- reduces blood flow to the bladder.
What is osmotic thirst?
Stimulated by high extracellular solute concentration.
What is the main component of angiotensin cascade?
If blood volume decreases, kidneys release renin, which triggers formation of angiotensin II. Angiotensin is released in hypovolemic thirst.
Where does the angiotensin II act?
In the subfornical organ to signal other brain sites to initiate drinking
What responds to blood osmotic pressure? What happens to the cell membranes? How do they respond?
Osmosensory neurons in anterior hypothalamus (OVLT). Their cell membranes shrink, opening mechanical-gated NA+ channels.
They respond by causing the pituitary to release antidiuretic hormone
What is the gustatory pathway?
Neurons from the tongue project through the nucleus of the solitary tract (NST) and thalamus to the insula (the primary gustatory cortex)
What are the mechanisms for dietary selection?
- Sensory-specific satiety
Food is less appealing the more you eat, encouraging variation in choices. Area NST of the Medulla - Learned taste aversion
Avoiding food associated w/ illness or poor nutrition - Learned taste preference
Preference for the flavor of a food that contains a needed nutrient
What is the principle fuel for energy?
Glucose
What form is glucose stored in the liver?
Glycogen
What is glycogenesis?
Converting glucose to glycogen, need INSULIN, this decreases glucose levels in the blood
What is needed to change glycogen back into glucose?
Glucagon
What is cortisol and where is it produced? What increases cortisol levels?
It is the stress hormone
It is produced in the adrenal glands
Both short term and chronic stress
What leads to the release of cortisol levels?
Low blood glucose concentration leads to its release, so levels are highest before a meal
