Hormones

Question 1

define hormone

Answer 1

chemical substance secreted into blood plasma by endocrine glands, affects target organs

Question 2

endocrine glands

Answer 2

ductless glands which secrete hormones into extracellular fluid around gland, hormone passes into blood capillary and is transported by blood

Question 3

exocrine glands

Answer 3

secrete into a duct which carries secretions into a body cavity or onto body surface

Question 4

lipid soluble

Answer 4

• bind to transport proteins in the blood, travel through bloodstream
• reach target organ, separates from transport protein, diffuses across cell membrane
• bind with receptor proteins in cytoplasm or nucleus, forms receptor-hormone complex
• activates genes which control formation of particular proteins by
• binding to promotor section of gene, stimulates or inhibits transcription and hence protein synthesis
• slow to have effect, long lasting
  eg sex hormones, cortisol, aldosterone

Question 5

water soluble

Answer 5

• unable to diffuse across membrane
• binds to receptor protein on surface of cell membrane of the target cell
• triggers release of secondary messengers which diffuse through cell, activating particular enzyme
• enzyme amplification
• quick to cause effect, short lasting

Question 6

3 characteristic of hormone receptor

Answer 6

specific - each receptor only binds with 1 particular hormone
saturation - all receptor molecules are occupied by hormones, due to limited number of receptor proteins on the hormone of the cell, rate of cell activity does not increase
each cell has different type and quantity of receptors, variations in sensitivities of cells to receptor hormones

Question 7

enzyme amplification

Answer 7

• hormones trigger cascading effect in which number of reacting molecules involved is increasing thousands of times for each step of metabolic pathway
• small stimulus produces large effect

Question 8

hormone clearance

Answer 8

broken down in liver kidneys target organ, excreted in urine or bile

Question 9

what do hormones do

Answer 9

changes functioning of cells by changing type, activity of, quantity of proteins produced
TYPE: activates certain genes in nucleus such that particular enzyme or structural protein is produced
ACTIVITY: change shape or structure of enzyme
QUANTITY: change rate of production of protein by changing rate of transcription translation

Question 10

anterior pituitary gland and hypothalamus

Answer 10

• pituitary gland is joined to the hypothalamus by a stalk called the infundibulum
• no nerves connecting it to the hypothalamus, but connected by complex network of blood vessels lying in the infundibulum
• releasing and inhibiting factors are released from the hypothalamus, travel through infundibulum to reach pituitary, controls secretions of anterior pituitary gland

Question 11

posterior pituitary gland

Answer 11

• pituitary gland joined to hypothalamus by stalk called infundibulum
• nerve fibres coming from nerve cell bodies in the hypothalamus pass through infundibulum to posterior pituitary gland
• hormones produced by hypothalamus are passed along long extensions of nerve cells through infundibulum to posterior pituitary gland, to be stored and released
• does not secrete its own hormones

Question 12

compare nervous and endocrine

Answer 12

nature of message - electrochemical/chemical
transport of message - along membrane of neurons/ by blood stream
type of response - usually local and specific/general and widespread
time taken to respond - milliseconds/seconds to days
duration of response - stops quickly when stimulus stops/longer lasting, may continue long after stimulus has stopped

Question 13

FSH

Answer 13

growth of follicles
production of sperm

Question 14

LH

Answer 14

ovulation, maintenance of corpus luteum
secretion of testosterone

Question 15

growth hormone

Answer 15

muscle growth and protein synthesis, development of bone tissue

Question 16

TSH

Answer 16

secretion of hormones from the thyroid

Question 17

ACTH

Answer 17

secretion of hormones from the adrenal cortex

Question 18

prolactin

Answer 18

milk production

Question 19

ADH

Answer 19

increases the permeability of the collecting ducts and DCTs of the nephrons of the kidneys, allowing for the reabsorption of water from nephrons

Question 20

Oxytosin

Answer 20

contraction of uterus during childbirth
release of milk

Question 21

thyroxine, triiodothyronine

Answer 21

increases metabolic rate and therefore oxygen consumption and heat production

Question 22

calcitonin

Answer 22

decrease calcium and phosphate levels in the blood
too high Ca: reduce reabsorption of Ca by kidneys and breakdown of bone
too high P: reduces reabsorption, moves P into bones

Question 23

Parathyroid hormone

Answer 23

increase level of calcium in blood
increase calcium released from bones, absorbed from digested food in small intestine, reabsorption from urine
increases phosphate excretion

Question 24

thymosins

Answer 24

development and maturation of T lymphocytes

Question 25

aldosterone

Answer 25

increase reabsorption of Na, excretion of K

Question 26

cortisol

Answer 26

promotes normal metabolism
help body deal with stress
promotes repair of damaged tissues

Question 27

adrenaline and noradrenaline

Answer 27

prolongs and intensifies fight or flight response, reinforces effects of sympathetic

Question 28

testosterone

Answer 28

sperm production
growth of skeleton and muscles
development of male sexual characteristics

Question 29

oestrogen

Answer 29

stimulates development of female sexual characteristics, regulates menstrual cycle

Question 30

progesterone

Answer 30

regulates menstrual cycle and pregnancy, prepares mammary glands for milk secretion