Quantatitive Cellular Physiology Exam 4 GENERAL INFO

How is a classic endocrine gland identified?

1. Remove the gland, does hormone deficiency and associated symptoms) result?

2. Replace the hormone, does it eliminate the symptoms?

3. Create hormone excess, do symptoms of hormone excess appear?

How is a hormone defined?

Hormones are chemicals secreted by cells or a gland, released into the bloodstream, transported to a distant target at very low concentrations.

How does the body regulate its response to hormones?

receptors! the type of receptor will determine the effect on the target cell

What are the characteristics of peptide/protein hormones? Examples?

Made from amino acids, released by Ca2+ mediated exocytosis. They dissolve easily in the blood/ECF, have short half lives, bind to cell surface receptors. This makes the response fast, but short lived. Examples include insulin, glucagon.

What are the characteristics of steroid hormones? Examples?

Steroid hormones cannot be held in vesicles, are NOT soluble in plasma. They are usually bound to carrier proteins and act as transcription factors when they bind to nuclear receptors. Long lasting but slow effects. Examples include aldosterone, cortisol.

how is the endocrine system related to the CNS?

Stimuli integrated by the CNS can trigger the secretion of neurohormones that influence hormone release.

How does the anterior pituitary interact with the hypothalamus to impact hormone release?

The AP is connected to the hypothalamus by portal blood vessels. The hypothalamus sends neurohormones, stimulating the AP and triggering it to release systematic hormones (TSH, LH, FSH, GH, ACTH).

How does the hypothalamus interact with the posterior pituitary gland?

The posterior pituitary is connected to the hypothalamus by neural pathways. The cell bodies in the hypothalamus produce the hormones, and they are released by axon terminals in the posterior pituitary (ADH and oxytocin)

What does ADH do in the body?

Regulates body osmolarity; increases water absorption in kidneys and constricts blood vessels to increase blood volume and pressure.

What type of hormone is growth hormone? What are it’s primary targets?

Peptide hormone, secreted by anterior pituitary, targets muscle, liver and bones.

What are the characteristics of GH release?

Burts every 2-4 hours, largest burst 1-2 hrs after falling alseep. Highest during puberty.

What are the major actions of GH?

Increase protein synthesis and organ growth. Increased amino acid uptake and DNA, RNA synthesis.

What is the rate limiting (and first step) of all steroid production?

cP-450 enzyme.

Characteristics of GC?

Synthesized in the middle zone of the adrenal cortex, mainly cortisol. Corticosterone can also be used, so if step 2 is blocked, GC will still be produced.

Characteristics of MC?

Main hormone is aldosterone. Made only in outer layer of the adrenal cortex, last 2 steps have alternate pathways.

Major androgen characteristics?

Synthesized in inner zone of the adrenal cortex. Converted to testosterone in the testes, so males do not need much. Women need a lot because

Which layers of the adrenal cortex are controlled by the hypothalamic-pituitary axis?

The inner and middle zones are controlled by the HP axis, while the outer zone depends on ACTH for the first step. It is then regulated by the renin-angiotensin-aldosterone system.

What hormone is the master regulator of all adrenal activity?

ACTH controls all adrenal hormone activity., about 10 bursts every 24 hours. Influenced by circadian rhythm, bc highest rates right before waking.

How does cortisol impact GC secretion?

Cortisol inhibits the hypothalamic secretion of CRH and the AP secretion of ATCH, and therefore GC secretion.

How do all adrenocortical steroids signal to cells?

nuclear receptors, they act as transcription factors.

Major actions of GC?

Stimulates the storage of glucose, anti-inflammatory, increases filtration rate in kidneys, fight or flight response, increases wake time.

How is MC secretion regulated?

By changes in ECF volume, potassium levels, stress

Major actions of MCs?

Increase Na+ reabsorption, increases K+ and H+ secretion, ECF VOLUME EXPANSION

What is the difference between a primary and a secondary adrenal insufficiency?

Primary is a defect in the adrenal cortex, secondary is a defect in the HP-Axis. Will have similar symptoms, but ACTH levels will be different.

What does the thyroid hormone impact?

Metabolism, protein synthesis, global hormone sensitivity. Promotes

How does TH act in the bloodstream and signal?

It is usually attached to thyroxine-binding globulin in the blood, only free TH is active. T4 is converted to T3 and binds to nuclear receptors to act as transcription factors.