Introduction

Question 1

Hormones act via receptors, where can they be located?

Answer 1

on the surface or within the cell

Question 2

Lipid soluble hormones

• mechanism of action
• examples

Answer 2

• bind to receptors located within the cells
• bind to nuclear receptor –> mRNA synthesis –> ribosome –> hormone production
• process is slow

-progesterone, testosterone, aldosterone, estrogen, calcitriol

Question 3

Water soluble hormones

• mechanism of action
• examples

Answer 3

• bind to receptors located on the cell membrane
• intracellular signaling cascade –> ATP –> cAMP –> cell response
• process is fast

-ACTH, calcitonin, epinephrine, glucagon, PTH, ADH

Question 4

Control of hormone secretion is regulated by:

Answer 4

1. Signals from nervous system
2. Chemical changes in blood
3. Other hormones

Question 5

Hypothalamus and Pituitary

Answer 5

• hypothalamus secretes inhibitory and releasing hormones. They regulate the release of anterior pituitary hormones
• anterior pituitary produces 7 hormones

Question 6

7 hormones that are secreted by the anterior pituitary

Answer 6

1. Human growth hormone (hGH)
2. Thyroid stimulating hormone
3. Follicle stimulating hormone
4. Luteinizing hormones
5. Prolactin (PRL)
6. Adrenocorticotropic hormone (ACTH)
7. Melanocyte stimulating hormone (MSH)

Question 7

1. Human growth hormone (hGH) (4)

Answer 7

• promotes synthesis of insulin like growth factors - somatomedins
• secreted by liver, muscle, cartilage, bones cells
• regulated by: hypothalamic hormones (growth hormone releasing and inhibiting) and blood glucose levels (low blood glucose levels –> released)
• actions: stimulates protein synthesis and makes “fuel” (ATP) available for growth

Question 8

2. Thyroid stimulating hormone (3)

Answer 8

• stimulates the formation and secretion of thyroid hormones (T3, T4) by thyroid gland
• regulation of TSH (negative feedback)
• low T3/T4 –> hypothalamus –> thyrotropin releasing hormone (TRH) –> TRH stimulates release of TSH –> TSH stimulates thyroid production of T3/T4

Question 9

3. Follicle stimulating hormone (4)

Answer 9

• in females - starts follicle development
• in males - sperm production in testes
• regulated by gonadotropin releasing hormones (GnRH) from hypothalamus
• increases estrogen in females

Question 10

4. Luteinizing hormones (4)

Answer 10

• in females - stimulates formation of corpus luteum
• in males - release testosterone from tests
• regulated by gonadotropin releasing hormones (GnRH) from hypothalamus
• increases estrogen and progesterone in females

Question 11

5. Prolactin (PRL) (5)

Answer 11

• initiates and maintains milk production by mammary glands
• ejection of milk is regulated by oxytocin
• prolactin inhibiting hormone (PIH) suppresses prolactin release
• high levels of estrogens –> PRH –> prolactin release
• hypersecretion –> erectile dysfunction

Question 12

6. Adrenocorticotropic hormone (ACTH) (4)

Answer 12

• controls production and secretion of glucocorticoids from adrenal cortex
• corticotrophin releasing hormones (CRH) from hypothalamus stimulates secretion
• stress-related stimulate can also stimulate the release of it
• glucocorticoids inhibit CRH and ACTH release

Question 13

7. Melanocyte stimulating hormone (MSH) (2)

Answer 13

• small amount in blood stream

- excess amount —> skin darkening

Question 14

Posterior pituitary

Answer 14

-release two hormones: oxytocin and antidiuretic hormone (ADH = vasopressin)

Question 15

Oxytocin causes… (3)

Answer 15

• smooth muscle contraction of uterus during childbirth
• causes “letdown” of milk glands to ducts
• some sexual pleasure during sexual activity

Question 16

Antidiuretic hormone (ADH = vasopressin) (3)

Answer 16

• causes kidneys to retain more water
• causes vasoconstriction –> increases BP
• dehydration, pain, stress –> increase ADH secretion

Question 17

Thyroid gland (4)

Answer 17

• follicular cells produce hormones and store them in follicles - T3 and T4
• parafollicular cells (C-cells) produce calcitonin
• T3 and T4 - increase basal metabolic rate, protein synthesis and growth. They are controlled by TRH and TSH
• Calcitonin - inhibits osteoclasts - strengthens bones, decreased blood Ca2+

Question 18

Parathyroid glands (4)

Answer 18

• release PTH –> increases blood Ca2+ in 3 ways:
  1. increases number and activity of osteoclasts that break down bone
  2. Slows loss of Ca2+ and Mg2+ in urine
  3. Promotes production of calcitriol (vitamin D) –> increases rate of Ca2+, Mg2+ and HO4P-2 absorption –> increase blood Ca2+

Question 19

Pancreas (3)

Answer 19

• exocrine and endocrine
• alpha cells –> glucagon
• beta cells –> insulin

Question 20

Actions of insulin and glucagon

Answer 20

Low blood glucose stimulate glucagon release
Glucagon stimulates liver to release glucose –> increase blood glucose

High blood glucose levels stimulate insulin release
Insulin increases glucose transport into skeletal muscle and adipose cells –> decrease blood glucose
Insulin promotes amino acid uptake, protein synthesis and lipid storage

Question 21

Adrenal glands

Answer 21

Adrenal cortex: 3 zones make steroids
Zona glomerulosa - Outer zone –> mineralocorticoids (aldosterone)
Zona fasciculata - Middle zone –> glucocorticoids (cortisol)
Zona reticularis - Inner zone –> androgens (testosterone)

Adrenal medulla: produces epinephrine (adrenalin) and norepinephrine

Question 22

Mineralocorticoids (3)

Answer 22

• aldosterone
• stimulates sodium and water reabsorption from urine to blood
• stimulates excretion of potassium into urine

Question 23

Renin-angiotensin-aldosterone pathway

Answer 23

1. Decreased BP
2. Release Renin from kidney
3. Renin acts on Angiotensinogen to form Angiotensin I
4. In lungs, angiotensin converting enzyme causes angiotensin I –> angiotensin II
5. Angiotensin II stimulates aldosterone release

Question 24

Glucocorticoid actions (6)

Answer 24

• increases rate of protein breakdown
• stimulates liver formation of glucose
• breaks down triglycerides in adipose
• anti-inflammatory effects
• depresses immune system
• regulated by negative feedback: CRH and ACTH

ex: cortisol

Question 25

Androgens (2)

Answer 25

- at puberty: stimulate axillary and pubic hair growth, contribute to adolescent growth spurt - in females --> contribute to libido, are converted to estrogens by other body tissues

Question 26

Adrenal Medulla (3)

Answer 26

- part of sympathetic nervous system - releases epinephrine and norepinephrine - actions mimic sympathetic nerves in stress --> increases HR and BP, increases blood glucose, dilates airways

Question 27

Pineal gland (4)

Answer 27

- small gland attached to roof of third ventricle of brain - produces melatonin - sets body's biological clock - more released in darkness, less in sunlight

Question 28

Stages of stress response

Answer 28

When successful leads to extra physiological capacity and long-term adaptation 1. Initial "fight-or-flight" response - aldosterone (raise blood pressure) 2. Resistance (slower) 3. Exhaustion (may occur eventually)

Question 29

Aging (7)

Answer 29

- Loss of negative feedback sensitivity so decline in circulating thyroid hormones - PTH levels rise --> loss of bone mass - Less glucocorticoid production - Slower release of insulin - Thymus declines after puberty - Ovarian response to gonadotropin stops - Slow decline in testosterone production