Endocrine System Physiology 1

Question 1

What do we call a chemical substance released by an endocrine gland into the blood in which it travels to another site in the body where it exerts its effect?

Answer 1

A hormone. Endocrine hormones are released directly into the bloodstream. Exocrine hormones are released into ducts to travel to the target tissue. Paracrine hormones act on cells within the vicinity of the secreting cell. Juxtacrine hormones act on neighboring cells. Autocrine hormones act on cells that produce the hormone.

Question 2

What is the difference between an exocrine and endocrine gland?

Answer 2

An endocrine gland secretes substances into the bloodstream without the use of a duct. An exocrine gland uses a duct to secretes substances to a place that is external from where it resides.

Question 3

What is an example of an exocrine gland?

Answer 3

Some examples are mammary glands, sweat glands, the pancreas, the liver, or salivary glands.

Question 4

What is an example of an endocrine gland?

Answer 4

Some examples are the ovaries, the testes, or the adrenal glands

Question 5

What are the 3 classes of hormones?

Answer 5

(1) Derived from amino acids

(2) Protein or peptide based

(3) Steroids

Question 6

What amino acid serves as the starting point of most of the amino acid derived hormones?

Answer 6

Tyrosine

Question 7

What 2 organs release tyrosine based hormones?

Answer 7

(1) Thyroid gland –> thyroxine

(2) Adrenal medulla –> Epi and Norepi

Question 8

What type of receptor when bound to hormone causes an increase in cAMP?

Answer 8

Plasmalemma receptors

Question 9

cAMP is an example of what?

Answer 9

Second messenger

Question 10

What is the effect of an increase in cAMP?

Answer 10

It causes an increase in cytosolic calcium

Question 11

What substances use plasmalemma receptors?

Answer 11

Polypeptide hormones like Norepi and Epi

Question 12

What receptors use cytoplasmic receptors?

Answer 12

Steroids

Question 13

How do steroids interact with the cytoplasmic receptor?

Answer 13

They bind to the receptor and the whole complex binds to DNA and induces gene expression to produce new proteins

Question 14

What substances use nuclear receptors?

Answer 14

T3 and T4

Question 15

What is the effect of T3 binding to a nuclear receptor?

Answer 15

Increased transcription and increased translation (production of proteins)

Question 16

GH, ACTH, TSH, FSH, LH, and prolactin come from where?

Answer 16

Anterior pituitary

Question 17

How is the hypothalamus and anterior pituitary connected?

Answer 17

Via portal vessels

Question 18

What gland is controlled by hypothalamic releasing substances?

Answer 18

Anterior pituitary (adenohypophysis)

Question 19

What gland is controlled by nerve signals from the hypothalamus?

Answer 19

Posterior pituitary (neurohypophysis)

Question 20

What stimulates growth of ovum and sperm?

Answer 20

FSH

Question 21

What stimulates the maturation and release of ovum?

Answer 21

LH

Question 22

What stimulates the liver to release somatomedins?

Answer 22

Growth hormone

Question 23

What promotes protein synthesis and uptake of various amino acids?

Answer 23

Growth hormone

Question 24

What promotes increased use of fats, release of fatty acids, decreased use of carbohydrates and increased beta oxidation?

Answer 24

Growth hormone

Question 25

Where are ADH and oxytocin released from?

Answer 25

Posterior pituitary

Question 26

What stimulates the release of GH from the Anterior pituitary?

Answer 26

GHRH

Question 27

What stimulates the release of GHRH from the hypothalamus?

Answer 27

Stress: malnutrition (especially protein), hypoglycemia, exercise, physical/mental trauma

Question 28

How does the hypothalamus affect posterior pituitary?

Answer 28

Hormones are produced by hypothalamus and are transported down nerve endings to the posterior pituitary

Question 29

What is target tissue for ADH?

Answer 29

Kidney collecting ducts. Collecting ducts contain lots of aquaporins and thus are highly permeable to water.

Question 30

What is main stimulus for release of ADH?

Answer 30

Increased blood osmolarity sensed by hypothalamus

Question 31

What mineral is important for synthesis of thyroid hormones?

Answer 31

Iodine

Question 32

What is the active form of thyroid hormone?

Answer 32

T3 aka triiodothyroxine. T4 is the inactive form.

Question 33

In what form is most of the thyroid hormone in the body?

Answer 33

T4/thyroxine

Question 34

How is thyroxin transported in blood?

Answer 34

It is bound to thyroxin binding globulin, prealbumin, or albumin

Question 35

What stimulates release of TRH?

Answer 35

Cold, emotional reactions, increased calories

Question 36

What is the function of thyroid hormone?

Answer 36

To maintain basal metabolic rate

Question 37

How does thyroid hormone maintain basal metabolic rate?

Answer 37

By increased activity of Na+/K+ ATPase pump

Question 38

What is the effect of calcitonin on the body?

Answer 38

Decreases blood calcium levels

Question 39

How does calcitonin decrease blood calcium?

Answer 39

Decreased activity of Ca2+ pump Increased osteoblastic activity --> bone formation Decreased osteoclastic activity --> less bone turnover

Question 40

Where is calcitonin released?

Answer 40

Thyroid gland, C cells

Question 41

What does parathyroid hormone do?

Answer 41

Increased calcium levels in the blood. Versus calcitonin decrease calcium levels in blood

Question 42

How does PTH increase calcium levels in the blood?

Answer 42

Increased intestinal absorption of calcium (with Vit. D3) Increased kidney reabsorption Increased bone resorption

Question 43

What are the two major controls of blood calcium?

Answer 43

PTH Vitamin D3 (helps calcium absorption)

Question 44

Where are catecholamines produced?

Answer 44

Adrenal medulla. Versus the adrenal cortex makes mineralocorticoids, glucocorticoids, and sex hormones.

Question 45

The adrenal medulla functions most like what kind of neuron?

Answer 45

Post ganglionic sympathetic neuron. Adrenal medulla developed embyrologically in parallel with the sympathetic nervous system.

Question 46

What four classes of hormones are released from adrenal cortex?

Answer 46

(1) Glucocorticoids (2) Mineralocorticoids (3) Androgens (4) Estrogens and progesterones

Question 47

How is cortisol transported?

Answer 47

Bound to globulins Bound to albumin Free form

Question 48

The fact that we need cortisol in small levels for other hormones to work is known as what?

Answer 48

Permissive effect

Question 49

What stimulates cortisol release?

Answer 49

ACTH

Question 50

ACTH exhibits diurnal variations. When is it at its highest?

Answer 50

In the morning

Question 51

What else is produced along with ACTH?

Answer 51

MSH - melanocyte stimulating hormone. This is why patients with Cushing's Syndrome (hypercortisolism) may also exhibit hyperpigmentation.

Question 52

What are some of the anabolic physiological activities of cortisol?

Answer 52

(1) Stimulates gluconeogenesis (2) Stimulates glycogen breakdown (3) Stimulates protein synthesis Anabolism refers to the synthesis of molecules (from simpler ones put together).

Question 53

What are some of the catabolic effects of cortisol at physiological doses?

Answer 53

1. Increased Protein catabolism in skeletal muscle, connective tissue, and lymphoid tissue 2. Increased Lipolysis 3. Increased Production of rate-limiting enzymes for gluconeogenesis Catabolism refers to the breakdown of molecules (into simpler ones).

Question 54

What are some of the other roles of cortisol at physiological doses?

Answer 54

Weak aldosterone effect Stimulates surfactant production in fetuses Anti inflammatory Enhances immune function

Question 55

What stimulates crf?

Answer 55

Stress e.g. hypoglycemia, intense hot or cold, chronic pain, emotions, disease

Question 56

What is the major mineralocorticoid?

Answer 56

Aldosterone

Question 57

What are the target tissues for aldosterone?

Answer 57

Kidney Sweat glands Salivary glands Colonic epithelium

Question 58

What are the major effects of aldosterone?

Answer 58

Regulation of blood volume and blood pressure

Question 59

How does aldosterone regulate blood volume and pressure?

Answer 59

(1) By causing an increase in Na+ reabsorption --> increased water reabsorption (2) Increased K+ excretion

Question 60

What is the long term control of aldosterone?

Answer 60

Angiotensin II

Question 61

What are some of the other controls of aldosterone?

Answer 61

Increased K+ (potent regulator) Decreased Na+

Question 62

What is needed for aldosterone to work?

Answer 62

ACTH

Question 63

What is the major adrenal androgen?

Answer 63

DHEA

Question 64

The delta cells of the islets of Langerhans produce what hormone?

Answer 64

Somatostatin

Question 65

What other organs produce somatostatins?

Answer 65

Stomach and intestines

Question 66

What effects do somatostatins have on the body?

Answer 66

Inhibits glucagon and insulin secretion from islets of Langerhans Inhibits GH and TSH Inhibits G.I. secretions such as CCK and secretin

Question 67

What hormone promotes fuel storage?

Answer 67

Insulin

Question 68

What will increase insulin release?

Answer 68

High blood glucose Sweet tasting food Amino acids

Question 69

What hormones increase insulin levels?

Answer 69

GI hormones --> cck, secretin and gastrin Cortisol

Question 70

What inhibits insulin release?

Answer 70

Epi and norepi and somatostatin

Question 71

What are the effects of insulin?

Answer 71

Increased cellular uptake of glucose Increased Glucose utilization Increased Glycogen synthesis Increased Fatty acid synthesis Increased Protein synthesis

Question 72

What hormone is released with low blood sugar?

Answer 72

Glucagon

Question 73

What are the main stimuli for release of glucagon?

Answer 73

Main stimuli --> Decreased blood sugar Increased Blood amino acids Epi/Norepi

Question 74

What are some of the effects of glucagon?

Answer 74

Increased blood glucose via: Increased Gluconeogenesis Increased Glycogenolysis Increased Triglyceride breakdown in adipose tissue

Question 75

Name 3 factors increase glucagon stimulation?

Answer 75

Low blood glucose, protein-containing meal, elevated levels of epinephrine