PHYS2- Steroid Hormones and the Adrenal Glands - III

Other Hormones Respond to Stress!! Increased secretion of.... (5) ***All coordinated by hypothalamus through posterior and anterior pituitary, and through sympathetic nervous system!

- Cortisol - ADH - Aldosterone - Glucagon (pancreatic) - Growth hormone

What are some results of prolonged stress?

- Hypertension - Hyperglycemia - Hyperlipidemia - Increase in infections - Insomnia - Headaches - Depression - Learning and memory problems

What are the 5 types of catecholamine receptors? **Distribution and affinity of receptors determines cell specific responses to epinephrine and norepinephrine

- alpha 1 and 2 (similar attributes) - beta 1, 2, and 3 (beta 3 is rare)

Role of Cortisol in Stress?

1) Increases metabolic fuels (glucose, fatty acids, amino acids) 2) Permissive for catecholamine- stimulated vasoconstriction and up-regulate glycogen synthase 3) Induces enzyme for production of epinephrine (proportion of epinephrine released by adrenal medulla increases)

Role of Glucagon during Stress?

1) Opposes effects of insulin (so it increases blood glucose levels)

Categories of Stressors (OVERVIEW)

1) Physical stressors - Cold, heat, radiation, noise, vibration, chemical stressors, pain, immobilization 2) Psychological stressors - Anxiety, fear, frustration 3) Social stressors - Unemployment, marital separation, death of partner 4) Stressors that challenge cardiovascular and metabolic homeostasis - exercise, orthostasis, upright tilt, hypoglycemia, hemorrhage

Role of ADH and Aldosterone during Stress?

1) Retention of sodium and water: - Protects ECF volume and blood volume - Important during heavy sweating and in case of blood loss

A student is having an acute anxiety attack about an upcoming exam. She will have: A) Reduced cardiac contractility B) Increased availability of energy substrates C) Constriction of her airways D) Constriction of coronary blood vessels E) Increased gastrointestinal motility

B

If aldosterone secretion were deficient, the ECF volume and blood volume would potentially be A) higher than normal B) lower than normal C) normal

B

Adrenal epinephrine contributes little to the constriction of bladder sphincters during acute stress because: A) Bladder sphincters are not constricted during acute stress B) Beta 2 receptors have little affinity for epinephrine C) Epinephrine release is inhibited during acute stress D) Bladder sphincters are controlled using alpha receptors

D

The Adrenal Medulla secretes about what percentage of epinephrine? percentage of norepinephrine?

EPI: 80% NE: 20%

The adrenal medulla releases catecholamines into the blood in response sympathetic activation caused by fright, danger, trauma, hemorrhage, hypoglycemia, vigorous exercise and other real or perceived stresses. Circulating catecholamines work through adrenergic receptors that modulate signaling pathways by means of _____ proteins.

G-coupled

________ are catecholamine-producing tumors of chromaffin cells of the adrenal medulla (90%) or extra-adrenal ganglia. Hypertension is the most common clinical feature. Other symptoms which may occur include tachycardia, tremors, sweating, anxiety and headache. Symptoms are often intermittent. Patients with this condition may also experience weight loss, an increased metabolic rate and glucose intolerance.

Pheochromocytomas

TRUE/FALSE: Epinephrine's effects are stronger than norepinephrine's effects during an acute stress response

TRUEEEEE

After DOPA becomes Dopamine, it is then transported into a secretory granule (chromaffin granule) called _________ and there it is converted to norepinephrine!

VMAT (vesicular monoamine transporter)

Catecholamine release by the adrenal medulla is an important part of the acute response to stress. Catecholamines are able to rapidly induce an array of adaptive responses by binding to and activating an assortment of ______ receptor subtypes.

adrenergic

Fight or Flight Response: Constriction of bladder and intestinal sphincters (via _____ receptor)

alpha

The different adrenergic receptors activate distinct intracellular signaling cascades! What type of signaling in.. alpha 1? alpha 2? Beta 1? Beta 2?

alpha 1 = Gq alpha 2 = Gi Beta 1 = Gs Beta 2 = Gs

Affinity of _____ receptors for NE > EPI, so epinephrine not very important for these responses to acute stress: - Vasoconstriction of skin, GI tract, kidneys - Intestinal relaxation (decreased motility) - Constriction of sphincters of intestines and bladder - Dilation of pupils - Piloerection (goosebumps)

alpha 1 and 2

Affinity of _____ receptors for NE = EPI, so epinephrine is somewhat important for these responses: - Increased heart rate - Increased cardiac contractility - Increased lipolysis (production of fatty acids)

beta 1

Fight or Flight Response: Increased oxygen delivery NEEDED for skeletal muscles and heart. Therefore we will see increased heart rate and contractility (via ______ receptor)

beta 1

Fight or Flight Response: Increased metabolic fuels of fatty acids (via _____ receptor) and of glucose (via ____ receptor)

beta 1; beta 2

Affinity of ______ receptors for EPI > NE, so epinephrine is especially important for these responses to acute stress: - Intestinal relaxation (decreased motility) - Bladder wall relaxation - Dilation of airways - Glycogenolysis

beta 2

Fight or Flight Response: Relaxation of smooth muscle in airways (via _____ receptor)

beta 2

Fight or Flight Response: Reduced digestion and excretion and therefore relaxation of bladder and GI tract (via _____ and ____ receptors)

beta 2 and alpha

Fight or Flight Response: Dilation of coronary and skeletal muscle blood vessels (via _____ receptor), constriction of other vessels (via _____ receptor), this causes redirecting of blood!!

beta 2; alpha

Strangely, ______ are NOT essential for life, but important in stress response. They support and add to widespread sympathetic response. Most cells have receptors for catecholamine. Some not innervated by the sympathetic nervous system and epinephrine is especially important for function of these cells.

catecholamines

Epinephrine and norepinephrine are the principal _______ released by the adrenal medulla. In humans, approximately 80% of the ______ cells secrete epinephrine. The remaining 20% secrete norepinephrine. The adrenal gland is the only source of circulating epinephrine. By contrast, most norepinephrine in the blood is released from _____ terminals.

catecholamines; chromaffin; nerve

In epinephrine-secreting chromaffin cells, norepinephrine exits the secretory granule by facilitated diffusion and is converted to epinephrine in the _______ by the action of _________. Epinephrine is then transported back into a chromaffin granule via a VMAT where it is stored until released by exocytosis.

cytoplasm; phenylethanolamine-N-methyltransferase (PNMT)

Fight or Flight Response indicates responses enhanced by _____

epinephrine

Cortisol is secreted into blood in the middle and inner zones of cortex, then flows to medulla.Increased secretion of cortisol stimulates conversion of _____ to _____. In these high cortisol situations, epinephrine can rises to > ____% of total catecholamines.

norepinephrine to epinephrine; 80

Because there are multiple adrenergic receptor subtypes, catecholamines are able to activate different signaling pathways. Consequently, they can have divergent effects such as the _______ of bronchial smooth muscle and the ______ of vascular smooth muscle. As part of the "fight or flight" response, catecholamines activate multiple responses that enable one to cope with emergency situations.

relaxation; constriction

In acute stress, called the "The Fight or Flight Response", there is sudden _____ outflow from the CNS. The body prepares for sudden intense activity during physical danger (also occurs with mental or emotional stress)

sympathetic

The adrenal medulla is a specialized ______ ganglion containing modified postganglionic cells (chromaffin cells) that secrete catecholamines directly into the blood stream. Chromaffin cells are innervated by ______ preganglionic fibers. The adrenal medulla is perfused by arterial blood from medullary arterioles and by blood from the cortical sinusoids which contains adrenal corticosteroid hormones. Both medullary arterioles and cortical sinusoids merge to form the medullary plexus.

sympathetic; cholinergic (N2)

Glucagon, cortisol, and epinephrine exhibit the phenomenon of _____ where their combined effects on raising glucose levels are greater than additive!!

synergism

What enzyme takes tyrosine-->DOPA??

tyrosine hydroxylase *(the first and rate limiting step in making NE and EPI)

How do we make NE and EPI? What are the precursor molecules??

tyrosine--> DOPA--> dopamine--> NE--> EPI