Lecture 6: Stress Response

Question 1

Explain the relationship between the hypothalamus and pituitary glands in number of hormones secreted by the two

Answer 1

The hypothalamus produces 9 hormones which are releasing or inhibiting hormones to control the pituitary.
The pituitary itself then can produce 7 hormones which enter the bloodstream to control the other endocrine organs to produce their own hormones which act more locally.

Question 2

What does the hypothalamus pituitary Axis regulate

Answer 2

They regulate growth, development, metabolism and homeostasis

Question 3

How does hormones produced in the hypothalamus travel to the pituitary

Answer 3

1. Hypothalamic neurosecretory cells get triggered to release hormones through the termini at the end of their axons which are close to their capillary network at the base of the hypothalamus.
2. Hormones travel through hypophyseal portal vein through secondary plexus to capillaries sitting on the anterior pituitary to then go to target cells in the pituitary.

Question 4

Describe the structure and location of the adrenal gland

Answer 4

ONe adrenal gland sits on top of each kidney. They have an outer capsule, with a cortex and then middle core called medulla.

Question 5

Compare the hormones are released by the Adrenal medulla with the Adrenal cortex

Answer 5

Medulla cells (modified post ganglionic “neurons (without axons)) secrete Epinephrine and Norepinephrine into the blood stream.

Whereas Adrenal cortex secrete mineralocorticoids and glucocorticoids

Question 6

What are the two stages of the Stress Response

Answer 6

1. ALARM response: Sympathetic autonomic activation: mobilise resources for immediate physical activity, get more oxygen and glucose into circulation, increase alertness and activity leading to fight or flight, Followed by Sympathetic activation of the Adrenal medulla (through ACh) which secretes epinephrine and norepinephrine into the blood to supplement and prolong the alarm response

2nd stage: (Resistance reaction) Stimulation of the adrenal cortex to produce cortisol (from CRH in hypothalamus -> ACTH from anterior pituitary) that helps to dampen inflammation, depress immune response to change balance to favour immediate tissue repair to reduce tissue damage if we get damage.

Question 7

What stimulates the adrenal medulla

Answer 7

Adrenal medulla is stimulated by sympathetic preganglionic neurons which release AcH at the synapse to the modified post ganglionic “neurons” acting as secretory cells in the medulla

Question 8

What is the effect of Norepinephine + Epinephrine

Answer 8

The effect is to act on the tissues already stimulated by the autonomic system as to enhance/ Sustain the sympathetic autonomic alarm response.

Question 9

What is the effect of mineralocorticoids

Answer 9

Mineralocorticoids increase Na+ conc and water and decrease K+ conc in the blood. This leads to increased blood volume and pressure.

Question 10

What stimulates the production of mineralocorticoids at the Adrenal cortex

Answer 10

Increased K+ concentration or Angiotensin 2 in the blood

Question 11

What stimulates the production of glucocorticoids at the Adrenal cortex

Answer 11

AdrenoCorticoTropinHormone (ACTH) made from the pituitary that was released into the blood stream. The hypothalamus told the pituitary to do this by releasing Corticotropin ReleasingHormone (CRH) into the primary hypophyseal plexus and then portal vein to the anterior pituitary.

Question 12

Give an example of a mineralocorticoid and glucocorticoid

Answer 12

mineralocorticoid: Aldosterone
glucocorticoid: Cortisol

Question 13

What is the effect of glucocorticoids

Answer 13

It does the resistance reaction to stress-

• increases glucose, fatty acids, and amino acids
• dampens inflammation
• It alters the balance of other immune responses changing the balance of B and T cells to deal with short term cuts and infection (suppresses immune response)
• sensitises vessels to vasoconstriction

Question 14

What are the 6 specific physiological reactions of the resistance reaction- actions of Coritsol- a glucocorticoid

Answer 14

1. Protein breakdown (in muscles) = allowing amino acids available for rebuilding of damaged tissue/ ATP production
2. Gluconeogenesis in the liver from amino acids/ lactic acids = glucose for ATP production
3. Lipolysis= breakdown of triglyceride and fatty acids can be used to build membranes
4. Vasoconstriction= vessels more sensitive to hormones that cause vasoconstriction leading to rise in blood pressure.
5. Anti-inflammatory= inhibiting white cells to limit tissue damage done by them. Also means slower wound healing
6. Immune depression, using the energy for other things, but then this leads to increased susceptibility to some infections

Question 15

what are the negative feedback controls of the cortisol release from adrenal cortex

Answer 15

1. Elevated cortisol levels inhibit the release of ACTH by anterior pituitary corticotrophs
2. Elevated cortisol inhibits the release of CRH by hypothalamic neurosecretory cells/

Question 16

What is the difference between Eustress and Distress

Answer 16

Eustress is acute - it prepares us to meet certain challenges so helpful/beneficial. Distress is chronic- it is associated with undesirable events that is potentially harmful due to activation from mental triggers.

Question 17

What is some consequence of habitually hostile people / stress cardiomyopathy syndrome

Answer 17

Chronic activation of the sympathetic ns, increasing blood pressure and cardiac output as well as more vasoconstriction of capillaries which leads to greater risk of cardiac infarct (heart attack)