Scope of hormones

Question 1

what are the 2 systems that control the body?

Answer 1

• endocrine system

- nervous system

Question 2

what is endocrinology?

Answer 2

the study of homeostatic chemical adjustments and other activities that hormones accomplish

Question 3

describe paracrine secretion

Answer 3

the hormone-secreting cell is close to the target cell eg. histamine

Question 4

describe neurotransmitter secretion

Answer 4

electrical signals transmitted by a neurone, reaching the target cells after passing a synapse

Question 5

describe hormonal secretion

Answer 5

the endocrine cells secrete chemicals into the blood which reaches the distant target cells

Question 6

describe neurohormone secretion

Answer 6

the neurones secrete neurohormones into the blood that will travel to distant target cells

Question 7

explain the difference between tropic and non-tropic hormones

Answer 7

• tropic hormones stimulate secretion of the hormone by another endocrine gland as their primary function
• non-tropic hormones act on target cells rather than endocrine cells (eg. insulin)

Question 8

trophic hormones

Answer 8

stimulate and maintain their target endocrine cells. eg. w out TSH, thyroid gland would shrink and thyroid production would drop.

Question 9

state the different types of hormones (eg. hydrophilic and lipophilic)

Answer 9

- Hydrophilic (low lipid solubility)
peptide hormones (eg. insulin)

- Lipophilic (low water solubility)
amine hormones (thyroid)
steroid hormones (testosterone)

Question 10

what are the effects of solubility on hormones

Answer 10

• how the hormone is processed by the endocrine cell
• how hormone is transported in the blood
• how hormone exerts its effects on the target cell

Question 11

describe the processing of hydrophilic peptide hormones by the endocrine cell

Answer 11

• prehormone is synthesised by ribosome on RER
• enzymes in the SER prune the prehormone into an active hormone
• hormone is pinched off in transport vesicles from the surface of SER and travels towards the Golgi apparatus
• it is modified and packaged into a secretory hormone which is stored in the cytoplasm
• on stimulation, its secreted by exocytosis

Question 12

describe the processing of lipophilic steroids hormones by the endocrine cell

Answer 12

• cholesterol is the common precursor to steroid hormones
• cholesterol is converted into steroid hormone through a series of enzyme controlled reactions
• these enzymes are limited to certain organs and cells
• steroid hormones aren’t stored, they are secreted after production by diffusing with the plasma membrane
• however, it is cholesterol that’s stored

Question 13

true or false?

all hormones are transported by blood

Answer 13

true, they are but not in the same manner

Question 14

how are hydrophilic hormones transported by the blood?

Answer 14

simply dissolved in the blood

Question 15

how are lipophilic hormones transported by the blood?

Answer 15

they reversibly bind to plasma proteins, some plasma proteins only carry one type of hormone, some carry any (albumin). only freely dissolved (unbound) hormones are active.

Question 16

what’s unusual about blood transportation of catecholamine hormones

Answer 16

50% dissolved in the blood, 50% bound to albumin

Question 17

where is the location of hydrophilic hormone receptors

Answer 17

they bind to specific receptor sites on the outer surface of the target cells.

Question 18

where is the location of lipophilic hormone receptors

Answer 18

bind to specific receptors located inside the cell

Question 19

how do hydrophilic hormones exert their effects on target cells

Answer 19

• they activate secondary messenger pathways within the target cells
• this alters the activity of pre-existing proteins within the cell

Question 20

how do lipophilic hormones exert their effects on target cells

Answer 20

• they activate specific genes inside the cells

- they alter intracellular gene expression

Question 21

what are the general mechanisms for hormone secretion

Answer 21

• negative feedback
• neuroendocrine reflexes (response to stress)
• diurnal (day-night) rhythms

Question 22

state the two endocrine disorders

Answer 22

hypo and hypersecretion

Question 23

describe hyposecretion of hormones

Answer 23

primary: abnormal gland
secondary: deficiency of tropic hormone acting on the gland, healthy gland
treatment: placement therapy

Question 24

describe hypersecretion of hormones

Answer 24

primary: abnormal gland
secondary: excessive stimulation from outside
causes: immunological problems/ tumors
treatment: removal of tumour, drugs