endocrine system

Question 1

hormone

Answer 1

chemical messengers secreted directly into the blood by endocrine glands (ductless glands) and specialized cells in tissues throughout the body

Question 2

endocrine system compared to the nervous system

Answer 2

• endocrine effects tend to be slower, more sustained
• endocrine messengers can affect wider variety of more distant targets
• the two systems coordinate responses, and some cells are “neuroendocrine cells”

Question 3

endocrine system

Answer 3

• system of communication through the use of hormones secreted via glands and cells

Question 4

neuroendocrine cells

Answer 4

cells that receive neuronal input (neurotransmitters released by nerve cells or neurosecretory cells) and, as a consequence of this input, release message molecules (hormones) to the blood

Question 5

target organ of corticotropin-releasing hormone

Answer 5

adrenal cortext

Question 6

target organ of coxytocin

Answer 6

uterus, mammary glands, brain

Question 7

location and position of adrenal glands to the rest of the endocrine glands

Answer 7

superior to kidneys

Question 8

adrenal medulla

Answer 8

• 10-2-% of gland, central location
• responds to sympathetic stimulation by secreting catecholamines (epinephrine, norepinephrine, and a small amount of dopamine) in response to stress
• raises metabolic rate and metablizes energy

Question 9

adrenal cortex

Answer 9

location:
- 80-90% of gland, outer part

function:
- secretes more than 31 corticosteroids (mineralocorticoids, glucocorticoids, and sex steroids) from cholesterol

3 tissue layers:
- zona glomerulos: most superficial layer
- zona fasciculata: intermediate, thick layer
- zona reticularis: deepest cortical layer

Question 10

zona glomerulosa

Answer 10

location/arranegment:
- outermost, thin layer of the cortex
- consists of cells arranged in small, round clusters

function:
- secretes mineralocorticoids that control electrolyte balance
- aldosterone targets kidney cells and causes sodium retention and potassium excretion, which affects blood volume and blood pressure

Question 11

zona reticularis

Answer 11

location:
- deepest cortical layer

function:
- weak androgens and small amounts of estrogen are secreted by the zona

Question 12

zona fasciculata

Answer 12

location/arranegment:
- thick middle layer
- consists of spongiocytes (cells) arranged in parallel cords perpendicular to the adrenal surface

function:
- produces glucocorticoids in response to ACTH
- glucocorticoids stimulate fat and protein catabolism, and release glucose and fatty acids to the blood
- principal glucocorticoid is cortisol, which helps the body respond to stress and tissue damage.

Question 13

anatomy of adrenal glands

Answer 13

2 distinct protions: adrenal cortex & adrenal medulla

Question 14

location and position of thymus to the rest of the endocrine glands

Answer 14

located in the mediastinum superior to the heart

Question 15

anatomy of the thymus

Answer 15

• aka a bilobed gland
• large in children and infants and involutes around age 14

function:
- site of maturation for white blood cells (T cells), the T lymphocytes (T for thymus) that play a critical role in immune response
- secretes a number of hormones (Thymopoietin, thymosin, and thymulin) that stimulate the development of other lymph organs and regulate the development and activity of T lymphocytes

Question 16

what hormones have an effect on blood pressure?

Answer 16

• aldosterone: causes sodium retention and potassium excretion which affects blood volume and blood pressure
• natriuretic peptides: lowers BP
• angiotensinogen: raises BP

Question 17

what glands regressed after childhood?

Answer 17

• adrenal glands (steroids): shrink in size early in life
• thymus, and pineal glands (melatonin): atrophy after puberty
• insulin secretion and effectiveness declines in old age (fewer insulin receptors)
• growth hormone and testosterone production decline with age, as do estogen levels

Question 18

origin of insulin

Answer 18

beta cells from the pancreatic islets

Question 19

function of insulin

Answer 19

insulin secretion by beta cells occurs in response to rising levels of blood glucose after a meal
- stimulates cells to absorb glucose (blood sugar), and antagonizes the effects of glucagon.