the endocrine system - primary endocrine glands

Question 1

thyroid gland anatomy

Answer 1

-below larynx
-made up single layer of epithelial cells called thyroid follicular epithelial cells

Question 2

hormones of the thyroid gland

Answer 2

-T3/T4
-calcitonin

Question 3

thyroid follicular epithelial cells

Answer 3

-have receptors for TSH from anterior pituitary gland
-TSH stimulates synthesis of thyroid hormones (T3 & T4)

Question 4

thyroxine (T4) & triiodothyronine (T3)

Answer 4

-T4: about 90% produced
-T3: about 10% produced
-produced by thyroid follicles
-regulates basal metabolic rate (BMR) of all cells
-influences physical/mental development + growth

Question 5

HYPOsecretion of T3/T4

Answer 5

LOW basal metabolic rate (BMR)
-put on weight easier
-feel cold easier
-low cardiac output
-sluggish tendon reflexes
-muscle weakness

Question 6

HYPERsecretion of T3/T4

Answer 6

HIGH basal metabolic rate (BMR)
-weight loss
-feel agitated frequently
-high cardiac output (hear beats stronger/faster)

Question 7

calcitonin

Answer 7

-produced by parafollicular cells (outside thyroid follicles)
-influences bone + calcium metabolism
-regulates blood calcium levels

Question 8

parathyroid gland

Answer 8

-two pairs of parathyroid glands located on dorsal (back) side of the thyroid gland
-secretes parathyroid hormone (PTH)

Question 9

parathyroid hormone (PTH)

Answer 9

plays role in calcium balance alongside calcitonin in a counter-regulatory manner

Question 10

blood calcium level too high

Answer 10

-thyroid gland releases more calcitonin in response
-calcitonin acts to stimulate fall in blood calcium levels (is taken up by bone)

Question 11

blood calcium level too low

Answer 11

-activates parathyroid glands to release PTH
-encourage mobilisation of calcium from bone to restore blood levels to homeostatic setpoint

Question 12

pancreas anatomy

Answer 12

-an exocrine and endocrine gland
-much of its tissue made up of acinar cells (exocrine)
-small clusters of cells called islets of Langerhans (endocrine)

Question 13

exocrine gland

Answer 13

-specialises in producing fluid into a ductile system
-that fluid goes off to drain in its respective structure

Question 14

acinar cells

Answer 14

-manufacture sodium bicarbonate (to create alkaline conditions)
-secrete digestive enzymes that are deposited in the duodenum

Question 15

islets of Langerhans

Answer 15

-manufacture and secrete two key hormones
-beta cells: insulin
-alpha cells: glucagon

Question 16

glucagon

Answer 16

-facilitates the breakdown of glycogen to glucose
-puts glucose back into circulation to raise blood sugar levels

Question 17

insulin

Answer 17

-essential for maintenance of normal blood sugar levels
-stimulates glucose uptake by many tissues
-inadequate levels result in diabetes mellitus

Question 18

adrenal glands anatomy

Answer 18

-situated on top of each kidney
-inside is called medulla
-outside layer is called the cortex

Question 19

adrenal cortex

Answer 19

produces two key hormones:
-cortisol
-aldosterone

Question 20

cortisol (a glucocorticoid)

Answer 20

-regulates carbohydrate, protein + fat metabolism
-works in conjunction with insulin/glucagon
-has an anti-inflammatory effect (dampens immune system)
-helps body cope during times of stress (mobilises glucose)

Question 21

aldosterone (a mineralocorticoid)

Answer 21

-promotes sodium and chloride retention
-promotes potassium excretion

Question 22

regulation of cortisol secretion from adrenal cortex

Answer 22

-hypothalamic-pituitary-adrenal (HPA) axis
-corticotropin-releasing hormone (CRH)
-CRH neurons activated (by stress) secrete CRH
-CRH reaches corticotrope cells in ant. pituitary gland
-corticotropes produce adrenocorticotropic hormone (ACTH)
-ACTH enters peripheral circulation to act on adrenal cortex to stimulate cortisol production (and aldosterone but lesser extent)

Question 23

regulation of aldosterone

Answer 23

local mechanism in kidney called renin-angiotensin-aldosterone system (RAAS)

Question 24

adrenal medulla

Answer 24

produces:
-adrenaline (epinephrine)

Question 25

adrenaline

Answer 25

-raises systolic blood pressure, heart rate + cardiac output
-speeds up release of glucose from liver
-dilates bronchial tubes + relaxes airways
-together with noradrenaline promotes ‘fight/flight’ response

Question 26

regulation of adrenal medulla via autonomic nervous system

Answer 26

-hypothalamus stimulated by stress, physical activity, low blood glucose
-action potentials travel down sympathetic nerves activating adrenal medulla
-promote release of adrenaline (+noradrenaline from sympathetic nerves)
-adrenaline+noradrenaline reach target tissues