animal coordination, control and homeostasis

Question 1

Describe where hormones

Answer 1

• hormones are produced and secreted by endocrine glands

Question 2

describe how the pituitary gland transports hormones to its target organ

Answer 2

• produces many hormones that regulate body conditions
• pituitary gland is the master gland situated at the base of brain
• releases hormones that act on other glands to release hormones that bring about change
• ADH targets the kidneys

Question 3

describe how the thyroid gland transports hormones to its target organ

Answer 3

• produces thyroxine (regulates things like rate of metabolism, heart rate and temperature)
• located at the front of your neck
• targets liver and kidneys

Question 4

describe how the pancreas transports hormones to its target organ

Answer 4

• produces insulin
• targets liver

Question 5

describe how the adrenal gland transports hormones to its target organ

Answer 5

• adrenalin
• liver, heart

Question 6

describe how the ovaries transports hormones to its target organ

Answer 6

• oestrogen and progesterone
• targets uterus

Question 7

describe how the testes transports hormones to its target organ

Answer 7

• testosterone
• male reproductive organs

Question 8

Explain that adrenalin is produced by the adrenal glands
to prepare the body for fight or flight
a) increased heart rate and blood pressure

Answer 8

• adrenaline binds specific receptors in the heart
• heart muscle contracts now more frequently and with more force
• heart rate and blood pressure increase

Question 9

Explain that adrenalin is produced by the adrenal glands
to prepare the body for fight or flight
b) increased blood flow to the muscles

Answer 9

• blood pressure and heart rate increases which increases blood flow to muscles
• so the cells receive more oxygen and glucose for increased respiration

Question 10

Explain that adrenalin is produced by the adrenal glands
to prepare the body for fight or flight
c) raised blood sugar levels by stimulating the liver to
change glycogen into glucose

Answer 10

• binds receptors to the liver so it breaks down its glycogen stores to release glucose
• this increase blood glucose levels so there is more glucose in the blood to be transported to the cells

Question 11

what is “fight or flight”

Answer 11

• adrenaline prepares body to either stand its ground in face of a threat or run away by activating processes that increase supply of oxygen and glucose to the cells

Question 12

Explain how thyroxine controls metabolic rate as an
example of negative feedback
a) low levels of thyroxine stimulates production of TRH
in hypothalamus

Answer 12

hypothalamus (structure in brain) produces TRH
- lower means hypothalamus is stimulated to release TRH

Question 13

low levels of thyroxine stimulates production of TRH
in hypothalamus
b) this causes release of TSH from the pituitary gland

Answer 13

• TRH stimulates pituitary gland to release TSH

Question 14

low levels of thyroxine stimulates production of TRH
in hypothalamus
c) TSH acts on the thyroid to produce thyroxine

Answer 14

• TSH stimulates thyroid gland to release thyroxine
• so blood thyroxine levels rise back towards normal

Question 15

Explain how thyroxine controls metabolic rate as an
example of negative feedback
d) when thyroxine levels are normal thyroxine inhibits
the release of TRH and the production of TSH

Answer 15

• when higher than normal the release of TRH is inhibited which reduces production of TSH so blood thyroxine levels fall

Question 16

what is negative feedback on hormones

Answer 16

• body detects level of substance has gone above or below the normal level it triggers a response to bring the level back up to normal

Question 17

Explain the interactions of oestrogen, progesterone, FSH
and LH in the control of the menstrual cycle

Answer 17

• FSH released by pituitary gland causes a follicles (egg and surrounding cells) to mature in one of the ovaries which stimulates oestrogen production
  -oestrogen released by ovaries causes lining to thicken and grow and a high level stimulates and LH surge
• LH released by pituitary gland, the surge stimulates ovulation at day 14 and the follicle release egg, stimulates the remains of the follicle to develops structure called corpus luteum which secrets progesterone
• progesterone released by corpus luteum after ovulation maintains lining of uterus, inhibits release of FSH and LH and when progesterone levels fall and there’s a low oestrogen level the uterus lining breaks down, low progesterone levels allows FSH to increase and cycle starts again

Question 18

Describe the stages of the menstrual cycle, including the roles
of the hormones oestrogen and progesterone

Answer 18

• oestrogen repairs and thicken uterus lining and progesterone maintains uterus lining
  1. lining of uterus breaks down
  2. uterus lining is repaired
  3. egg develops and is released from ovary (ovulation)
  4. lining is maintained

Question 19

Explain how hormonal contraception influences the menstrual
cycle and prevents pregnancy a) oestrogen

Answer 19

• prevents the release of an egg
• if taken every day to keep level of oestrogen permanently high it inhibits production of FSH

Question 20

Explain how hormonal contraception influences the menstrual
cycle and prevents pregnancy b) progesterone

Answer 20

• reduces fertility
• stimulates production of thick cervical mucus which prevents sperm getting through uterus cervix and reaching egg

Question 21

Explain how hormonal contraception influences the menstrual
cycle and prevents pregnancy c) oestrogen and progesterone

Answer 21

• combined pill and contraceptive patch

Question 22

Evaluate hormonal and barrier methods of contraception

Answer 22

hormonal
-when used correctly hormonal methods are more effective at preventing barrier methods
- don’t have to stop and think about contraception
barrier
- protect against sexually transmitted infection (only condoms do this)
- hormonal methods can have side effects like headaches, acne and mood changes

Question 23

Explain the use of hormones in Assisted Reproductive
Technology (ART) in clomifene therapy

Answer 23

• clomifene is used when women are infertile because they don’t ovulate or don’t ovulate regularly
• causes more FSH and LH to be released by the body which stimulates egg maturation and ovulation
• knowing when woman will be fertile couple can have intercourse during the time period

Question 24

Explain the use of hormones in Assisted Reproductive
Technology (ART) in IVF

Answer 24

• IVF collects eggs and fertilises them in a lab
• ART is a fertility treatment where eggs are handled and fertilised outside the body
• once developed into embryos and the embryos are tiny balls of cells some of them are transferred to the woman’s uterus
• FSH and LH are given before egg collection, to stimulate egg production (so more than one egg can be collected)

Question 25

Explain the importance of maintaining a constant internal
environment in response to internal and external change

Answer 25

• conditions in your body need to be kept steady so cells have right conditions to function like right conditions for enzyme action
• to maintain this your body needs to respond to internal and external changes whilst balancing inputs with outputs (homeostasis)
• homeostasis ex blood glucose regulation, osmoregulation (water content), thermoregulation (body temperature)

Question 26

Explain how the hormone insulin controls blood glucose
concentration

Answer 26

• insulin is added if blood glucose concentration is too high
• blood with too much glucose -> insulin secreted by pancreas -> too much glucose -> insulin -> glucose moves from blood into liver and muscle cells -> blood glucose reduced
• insulin makes liver turn glucose into glycogen

Question 27

Explain how blood glucose concentration is regulated by
glucagon

Answer 27

• blood glucose concentration is too low - glucagon is added
• blood with too little glucose -> glucagon secreted by pancreas -> too little glucose -> glucagon -> glucose released into blood by liver -> blood glucose increased
• glucagon makes liver turn glycogen into glucose

Question 28

Explain the cause of type 1 diabetes and how it is controlled

Answer 28

• pancreas produces little or no insulin
• treated with insulin therapy so injecting insulin into the subcutaneous tissue (fatty tissue just under skin) so it enters the bloodstream
• often done at mealtimes so glucose is removed from the blood quickly once the food has been digested
• also need to think about limiting intake of rich foods in simple carbohydrates (sugars) and taking regular exercise to remove excess glucose from blood

Question 29

Explain the cause of type 2 diabetes and how it is controlled

Answer 29

• a person is resistant to insulin
• pancreas doesn’t produce enough insulin or when they become resistant to insulin -> blood glucose levels rise
• correlation between obesity and type 2 diabetes
• controlled by eating a healthy diet and getting regular exercise and losing weight, some people may have medication or insulin injections

Question 30

what is the BMI equation

Answer 30

BMI = mass (kg) / (height (m squared)) squared

Question 31

what is the waist: hip ratio

Answer 31

waist circumference (cm) / hip circumference (cm)