topic 7

Question 1

how does the endocrine system work

Answer 1

hormones (chemical messengers) are released from glands directly into the blood and carried in it to parts of the body, they produce a response when they reach a target tissue

slower than the nervous system but it acts for longer

Question 2

the pituitary gland

Answer 2

• the master gland
• secreted hormones into blood to have an effect on the body/act on other glands to stimulate production of different hormones

Question 3

pancreas

Answer 3

secretes insulin

controls blood glucose

Question 4

thyroid

Answer 4

secretes thyroxine

controls metabolic rate, heart rate and temperature

Question 5

adrenal gland

Answer 5

secretes adrenaline

involved in fight or flight response

Question 6

ovary

Answer 6

secretes oestrogen

involved in menstrual cycle and development in female secondary sexual characteristics

Question 7

testes

Answer 7

secrete testosterone

involved in sperm production and development of male secondary sexual characteristics

Question 8

aspects of the fight or flight response

Answer 8

• adrenaline is released from the adrenal glands
• increased heart rate - oxygen reaches muscles quicker so we can move away from danger
• increased blood pressure - ^
• increased blood flow to muscles - blood vessels dilate, allowing more blood to reach muscles so they can contract faster with greater strength
• increased blood sugar levels - liver is stimulated to break down glycogen into glucose, muscles can use it to contract

Question 9

thyroxine negative feedback loop

Answer 9

• low thyroxine levels stimulate TRH production in the hypothalamus
• TRH stimulates the release of TSH from the pituitary gland
• TSH stimulates the thyroid gland to release thyroxine
• thyroxine levels exceed the normal level and the release of TSH is inhibited, causing thyroxine levels to form

Question 10

oestrogen as contraception

Answer 10

permanently high oestrogen means FSH production is permanently inhibited, so after a while egg development stops and stays stopped

Question 11

progesterone as contraception

Answer 11

progesterone prevents FSH production so that no eggs mature in the ovaries

Question 12

FSH in menstrual cycle

Answer 12

it’s produced in the pituitary gland, stimulates an egg to mature in the follicle and stimulates ovaries to produce more oestrogen

Question 13

oestrogen in menstrual cycle

Answer 13

releases due to FSH, it’s released from the ovaries and causes the growth of the uterus lining, high levels then stimulate LH production and inhibit FSH secretion

Question 14

LH (luteinising hormone) in menstrual cycle

Answer 14

LH is produced in the pituitary gland as a result of oestrogen, it triggers ovulation at day 14 where the follicle ruptured and the egg is released, the remains are then stimulated to form a structure called corpus luteum that secretes progesterone

Question 15

progesterone in the menstrual cycle

Answer 15

• released from corpus luteum post ovulation, maintains uterus lining and if an egg is implanted would maintain high levels
• high oestrogen and progesterone levels inhibit LH and FSH production, low levels then restart the cycle

Question 16

order of hormones in the menstrual cycle

Answer 16

FSH
oestrogen
LH
progesterone

Question 17

metabolic rate

Answer 17

the amount of energy expended by an organism in a given time period, usually daily

Question 18

outline the menstrual cycle

Answer 18

it is the process the body undergoes each month to prepare for a potential pregnancy

• the uterus lining breaks down, and the person has their period
• the layer builds until ovulation on day 14 where an egg is released
• if a fertilised egg hasn’t been embedded in the uterus lining after 28 days, it breaks down and the cycle continues

Question 19

the mixed contraceptive pill

Answer 19

has to be taken regularly or the body’s hormones will be released and an egg will mature

• has oestrogen and progesterone
• constantly high oestrogen levels inhibit FSH so eggs can’t mature
• lining stops developing and cervical mucus becomes thick to stop sperm from moving through
• side effects: mood swings, depression, breast pain/enlargement, increased blood pressure

Question 20

progesterone only pill

Answer 20

has to be taken regularly to prevent the body’s own hormones releasing and an egg maturing

• high progesterone levels inhibit FSH and LH release, so an egg can’t mature
• it has less side effects than the mixed pill

Question 21

contraceptive patch

Answer 21

• oestrogen and progesterone
• small, stuck on the skin
• lasts for 1 week

Question 22

contraceptive implant

Answer 22

• releases a continuous amount of progesterone
• lasts for 3 years
• prevents release of eggs from ovaries, thickens cervical mucus, stops eggs embedding in uterus

Question 23

contraceptive injection

Answer 23

• progesterone
• prevents release of egg from ovaries, thickens cervical mucus, stops fertilised eggs from embedding in the uterus
• lasts 2-3 months

Question 24

intra-uterine device (IUD)

Answer 24

• releases progesterone
• T-shaped, inserted into uterus
• lasts 5-10 years
• prevents release of egg from ovaries, thickens cervical mucus, stops fertilised eggs from embedding in the uterus

Question 25

clomifene therapy

Answer 25

* clomifene is a drug * it increases FSH and LH released from pituitary, increasing chances of a woman ovulating * woman can then get pregnant naturally

Question 26

IVF

Answer 26

*  FSH and LH is given to encourage the maturation and release of eggs * these are extracted and then fertilised using sperm in the lab * fertilised eggs developing into embryos and 1/2 are inserted into the uterus

Question 27

cons of IVF

Answer 27

* physically stressful bc she may have reactions to the hormone eg. feeling sick *  emotionally stressful bc it may not work, 26% success * can lead to multiple births, may be a risk to mother+babies * can be £££ if process needs repeating

Question 28

define homeostasis

Answer 28

the maintenance of a constant internal environment

Question 29

why is thermoregulation important

Answer 29

if the temp exceeds 37 ˚C, enzymes will become less effective and eventually denature

Question 30

why is osmoregulation important

Answer 30

* blood is too dilute = water will move into cells by osmosis an they'll burst under the pressure * blood is to concentrated - water moves out of cells and they shrink in either case, they can't perform their function

Question 31

how does the body know when to thermoregulate

Answer 31

* receptors monitor blood temperature | * receptors in the skin send impulses to the thermoregulatory centre (found in the hypothalamus)

Question 32

negative feedback loop with blood glucose

Answer 32

* eating carbs increases blood glucose * high glucose levels - pancreas produces the hormone insulin * insulin binds to cells in muscles and liver * excess glucose is converted into glycogen which is stored in the liver *  blood glucose concentration reduces * pancreas produces the hormone glucagon * it binds to liver cells and causes glycogen to be broken down to glucose * glucose is released into the blood and the conc increases REPEAT!

Question 33

type 1 diabetes

Answer 33

the pancreas can't produce enough insulin * blood glucose can rise fatally *  glucose is excreted with urine --> lots of urine --> thirsty * insulin injections at mealtimes + advised to limit simple carbohydrates with lots of glucose

Question 34

type 2 diabetes

Answer 34

body cells no longer respond to insulin *  blood glucose levels can rise to a fatal amount * obesity is a risk factor * limit simple carbohydrates, lose weight, exercise * there are drugs to make insulin more effective on body cells/ make more insulin/ reduce amount o glucose absorbed by gut

Question 35

how is BMI calculated

Answer 35

mass (kg)/height^2(m)

Question 36

what BMI is considered as obese

Answer 36

30+

Question 37

what is the urinary system

Answer 37

the bodily system that removes impurities and waste products from our blood, which are excreted in urine

Question 38

what is the route that blood takes to be purified

Answer 38

* blood to the kidneys through the renal artery * the kidneys regulate salt, ion and urea levels in the blood * excess is sent to the ureter for excretion and eventually the bladder * the purified blood returns for circulation through the renal vein

Question 39

structure and function of nephrons

Answer 39

* glomerulus - ultrafiltration occurs, urea, water, ions and glucose (not protein/cells) pass out of the capillaries into the Bowman's capsule * proximal convoluted tubule - selective reabsorption of glucose and ions (all glucose is reabsorbed bc its needed for energy) * loop of Henle and collecting duct - reabsorption of some water and ions

Question 40

how does ADH work

Answer 40

* ADH is produced and released from the pituitary gland * too much water in the blood - less ADH is released, the collecting duct becomes less permeable and more water is released in urination and vice versa

Question 41

kidney dialysis

Answer 41

* blood is taken from an arm vessel and mixed with an anticoagulant * the dialysis fluid contains similar glucose and ion levels but no urea

Question 42

kidney transplants

Answer 42

* risk of rejection which can lead to severe illness or even death * immunosuppressants have to be taken for the rest of the patients life * tissue typing prevents rejection but often leads to long waits

Question 43

how is urea produced

Answer 43

by the breakdown of excess amino acids in the liver