Topic 7: Animal Coordination, Control and Homeostasis

Question 1

what are hormones

Answer 1

chemical messengers sent in the blood

Question 2

what type of glands produce hormones

Answer 2

endocrine

Question 3

what is the role of the pituitary gland

Answer 3

• produces many hormones that regulate body conditions and act on other glands by directing them to release hormones that bring about chnage

Question 4

what is the role of the thyroid gland

Answer 4

produces thyroxine which is involved in regulating rate of metabolism, heart rate and temperature

Question 5

what is the role of the overies

Answer 5

produce oestrogen which is onvoled in the menstural cycle

Question 6

what is the role of the adrenal glands

Answer 6

produces adrenaline which is used to prepare the body for a fight or flight response

Question 7

what is the role of testes

Answer 7

produce testosterone, which controls puberty and sperm production in males

Question 8

what is the role of the pancreas

Answer 8

produces insulin, which is used to regulate the blood glucose level

Question 9

compare how neurons and hormans are different

Answer 9

• neurons have a very fast action, but hromaones have a slower action
• neurones act for a very short time but hormones act for a long time
• neurons act on a precise area but hromones act in a more general way

Question 10

where is the hormone adrenalin released from

Answer 10

adrenal glands

Question 11

explain how adrenaline prepares the body for ‘fight or flight’

Answer 11

• adrenaline binds to specific receptors in the heart which causes the heart muscle to contact more frequently with more force so heart rate and blood pressure increases
• this increases blood flow to the muscles, so the cells recieve more oxygen and glucose for increases respiration
• adrenalin also binds to receptors in the liver which causes the liver to break down its glycogen stores to release glucose
• this increases the blood glucose level, so there is more glucose in the blood to be tranported to the cells

Question 12

what is negative feedback

Answer 12

when the body detects that the level f a substance has gone above or below the normal level, it triggers a response to bring the level back to normal again

Question 13

describe the negative feedback system of thyroxine regulating the metabolism

Answer 13

• when the blood thyroxine level is lower than normal, the hypothalamus is stimulated to release thyrotropic releasing homrone (TRH)
• TRN stimulates the pituitary gland to release thyroxine, so the blood thyroxine level rises back towards normal
  when the blood thyroxine level becomes higher than normal, the release of TRH from the hypothalamus is inhibited, which reduces the production of TSH so the blood thyroxine level falls

Question 14

what does a higher than normal thyroxine level also inhibit

Answer 14

the secretion of TSH from the pituitary gland

Question 15

explain what an underactive thyroid can cause

Answer 15

• can cause weight gain as less thyroxine is produced, so metabolic rate drops. This means that less of the glucose you take in gets broken down in respiration, so more is stored as fat

Question 16

describe the stages of the menstural cycle

Answer 16

stage 1: day 1 is when mestruation starts where the lining of the uterus breaks down and is released
stage 2: the uterus lining is repaired, from fay 4 to day 14, until it becomes a thick spongy later full of blood vessels ready for a fertillised egg to impant there
Stage 3: an egg develops and is released from the very at about day 14
stage 4: the lining in maintained for about 14 days until day 28. If no fetilised egg has landed on the uterus wall by day28, the spongy lining starts to break down again and th whole cycle starts over

Question 17

what 4 hormones is the menstural cycle controlled by

Answer 17

FSH
oestrogen
LH
progesterone

Question 18

describe how FSH controlls mentsural cycle

Answer 18

• released by pituitary gland
• causes a follicle (an egg and its surrounding cells) to mature in one of the overies
• stimulates oestrogen production

Question 19

describe how oestrogen controlls the menstural cycle

Answer 19

• released by the ovaries
• causes the lining of the uterus to thicken and grow
• a high level stimulates an LH surge

Question 20

describe how LH controlls the menstural cycle

Answer 20

• released by the pituitary gland
• the LH surge stimulates ovulation at day 14 - the follicle ruptures and the egg is released
• stimulates the remains of the follicle to develop into a strcutre called a corpus lute - which secretes progesterone

Question 21

describe how pogesterone controls the menstural cycle

Answer 21

• released by the corpus luteum after ovulation
• maintains the lining of the users
• inhibits the relesse of FSH and LH
• when the level of pogesterone falls, and there’s a low oestrogen level, the uterus lining breaks down
• a low progesterone level allows FSH to increase and the whole cycle starts again

Question 22

explain how hormones can be used to treat infertility in terms of clomifene therapy

Answer 22

• some women are infertile due to not ovulating or not ovulating regularly.
• clomifene is a drug that works by causing more FSH and LH to be released by the body which stimulates egg maturation and ovulation
• by knowing when the woman is ovulating the couple can have intercourse during this time period to improve the chnace of becoming pregnant

Question 23

explain how hormones can be used to treat infertility in terms of IVF

Answer 23

• IVF involves collecting eggs from the women’s ovaries and fertilising them in a lab using the man’s sperm
• these are grown into embryos which are then transferred to the womens uterus to improve the chance of preganancy
• FSH and LH are given before egg collection to stimulate egg production

Question 24

Explain how hormonal contraception influences the menstrual cycle and prevents pregnancy

Answer 24

Hormonal contraception (pills, implants or injection) release hormones to raise hormone concentrations which naturally fall.

OESTROGEN can prevent egg release if taken every day to keep it at high levels (inhibits FSH release). Egg maturation is stopped.

PROGESTERONE can stimulate production of THICK CERVICAL MUCUS (preventing sperm getting to the uterus) + reaching the egg.

Question 25

Evaluate hormonal and barrier methods of contraception

Answer 25

HORMONAL METHOD:
+ More effective at preventing pregnancy.
+ Couples don’t have to stop to think about contraception.
- DON’T PROTECT AGAINST STIs.

BARRIER METHOD:
+ Don’t have side effects e.g. mood swings/headaches.
+ CONDOMS PROTECT AGAINST STIs.

Question 26

what is IVF an example of

Answer 26

Assisted Reproductive Technology (ART)
- a fertility treatment that involves eggs being handled outside of the body

Question 27

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

Answer 27

Homeostasis prevents damage as it keeps conditions at optimal levels despite internal and external change. It is important for ENZYME ACTION (Fastest in certain conditions + at lower temperatures chemical reactions could occur at a slower rate, which is harmful for the body) + CELL FUNCTIONS, e.g. growth, replication + controlled cell death.

Question 28

describe osmoregulation as an example of homeostasis

Answer 28

• regulation of water content
• you need to keeo a balance between the water you gqain and the water you lose through urine, sweat and exhaling

Question 29

describe thermoregulation as an example of homeostasis

Answer 29

• regulating body temp
• you need to reduce your body temp when you’re hot, but increase temp when the environment is cold

Question 30

describe blood glucose regulation as an example of homeostasis

Answer 30

• you need to make sure the amount of glucose in your blood doesn’t get too high or too low

Question 31

define homeostasis

Answer 31

maintaining a constant internal
environment in response to internal and external change

Question 32

explain the importance of thermoregulation

Answer 32

if temp is too high then enzymes can denature so reactions cannot take place
- if temp is too low the molecules dont have eneough kinetic energy to make successful collisions so recations cannot take place

Question 33

explain the importance of osmoregulation

Answer 33

2) It’s really impportant that the water content of the blood is controlled to keep cells functioning normally.
2) If the concentration of water in the blood is too high then water will move into the body cells by osmosis. If too much water moves into the cells then the cells may burst.
3) If the concentration of water in the blood is too low then water will move out of the cells into the blood by osmosis. This causes the cells to

Question 34

Explain how thermoregulation takes place, with reference to
the function of the skin, including: the role of the dermis, the role of the epidermis, the role of the hypothalamus

Answer 34

DERMIS SEBACEOUS GLANDS produce oil that allows sweat to spread over the EPIDERMIS. Evaporating sweat transfers energy from the skin to surroundings so cools the skin down.

They produce little sweat om the cold to reduce energy transfers.

DERMIS ERECTOR MUSCLES relax so HAIR FOLLICLES lie FLAT. There’s a thinner layer of INSULATING air trapped against the EPIDERMIS

They CONTRACT in the cold so HAIR FOLLICLES are pulled upright, trapping an INSULATING layer of air against the EPIDERMIS.

The THERMOREGULATORY CENTRE (HYPOTHALAMUS) has receptors that receive impulses from EPIDERMIS + DERMIS skin receptors that provide information about the external temperature.
If the hypothalamus detects temperature change, a response occurs. It increases blood flow near the surface of the skin, cooling us down

Question 35

Explain how thermoregulation takes place, with reference to: shivering, vasoconstriction, vasodilation

Answer 35

SHIVERING (rapid muscle contraction + relaxation) Some energy is released from an increased rate of respiration, transferred to warm you up.

VASOCONSTRICTION is the narrowing of blood vessels. When the HYPOTHALAMUS detects cold, it sends nerve IMPULSES to skin arteries to cause them to narrow.
Blood flow in CAPILLARIES near the skin is REDUCED. Energy transfer to the surroundings is REDUCED to WARM the body.

VASODILATION is the widening of blood vessels. When the HYPOTHALAMUS detects warmth, it sends nerve IMPULSES to skin arteries to cause them to widen.
Blood flow in CAPILLARIES near the skin is REDUCED. Energy transfer to the surroundings is REDUCED to COOL DOWN the body.

Question 36

Explain how the hormone insulin controls blood glucose
concentration

Answer 36

When BLOOD GLUCOSE CONCENTRATION is TOO HIGH (e.g. after meals when glucose is released from carbs), there’s a risk it could DAMAGE ORGANS.

If the PANCREAS detects a rise in BLOOD GLUCOSE CONCENTRATION, it increases SECRETION of INSULIN.
Insulin causes MUSCLE/LIVER CELLS to remove glucose from the blood + change it into GLYCOGEN to be STORED.
With a decreasing blood glucose concentration, there’s decreasing insulin released until the level is normal (no insulin is released)

Question 37

Explain how blood glucose concentration is regulated by
glucagon

Answer 37

If the PANCREAS detects a fall in BLOOD GLUCOSE CONCENTRATION, it increases SECRETION of GLUCAGON.
Glucagon causes MUSCLE/LIVER CELLS to change GLYCOGEN into GLUCOSE to the blood + release it into the blood.
With a decreasing blood glycogen concentration, there’s decreasing glucagon released until the level is normal (no glucagon is released)

Question 38

Explain the cause of type 1 diabetes

Answer 38

The IMMUNE SYSTEM has destroyed pancreatic insulin-secreting cells so the person produces little/no insulin. Blood glucose can rise to levels that can kill them. (Glucose in the urine tests for type 1)

Question 39

how is type 1 diabetes controlled

Answer 39

CONTROL: Inject insulin into the SUBCUTANEOUS TISSUE to enter the blood (mainly at mealtimes to remove glucose quickly from the blood to stop the blood glucose concentration getting too high). The amount depends on diet /activity.

Question 40

Explain the cause of type 2 diabetes

Answer 40

Insulin-secreting cells don’t produce enough insulin, target organs don’t respond properly to it or a person (a person is RESISTANT to it)

Question 41

how is tyoe 2 diabetes controlled

Answer 41

Some only need to eat healthily/eat a low amount of sugar. Physical activity takes glucose out of the blood so can help.

MEDICINES are given to those with severe Type 2 diabetes, reducing the amount of glucose the liver releases in the blood/increases the sensitivity of target organ cells responding to insulin.

Question 42

Evaluate the correlation between body mass and type 2 diabetes including waist:hip calculations and BMI, using the BMI equation

Answer 42

• there is a correlation between obesity and type 2 diabetes - this means obese people have an icreased risk of developing type 2 diabetes.
• people are classified as obese if they have a BMI of over 30
• where the body stores excess fat is also important - storing a lot of fat around the abdomen is associated wit an increased risk of developing type 2 diabetes
• a ratio of above 1.0 for men and above 0.85 for women is associated with an increased risk fo typ2 diabetes

Question 43

what are the 3 main roles of the kidney

Answer 43

• removal of urea from the blood. urea is produced in the liver from the breakdown of excess amino acids
• adjustment of ion levels in the blood
• adjustment of water content of the blood

Question 44

describe what happens at each nephron in the kidney

Answer 44

• they liquid part of the blood is forced out of the glomerulus and into th ebowmans capsule at high pressure (ultrafiltration). Bigger molecules like proteins and blood cells can’t pass through the membranes and are not forced out
• as the liquid flows along the nephron useful substances are reabsorbed: all glucose is selectively reabsorbed by being moeved back into the blood against the concentration gradient, sufficient ions are reabsorbed and sufficient water is reabsorbed according to the level of the hromone ADH
• whatever isnt reabsorbed continues out of the neprhron via the collecting duct. It then passes into the ureter and down to the bladder as urine which is released through the urethra

Question 45

what hromone controls the amount of water reabsorbed in the kidney nephrons

Answer 45

anti-diuretic hromone (ADH)

Question 46

Explain the effect of ADH on the permeability of the collecting duct in regulating the water content of the blood

Answer 46

When the brain detects a lower water content, more ADH is released by the pituitary gland to make the nephrons and the collecting ducts more permeable. This makes it so more water can be reabsorbed back into the blood. This prevents dehydration.

Question 47

descibe effect of ADH when water content is too high

Answer 47

when the brain detects a higher water content it stimulates the pituitary gland to release less ADH so the kidney reabsorbs less water and maintains hydration

Question 48

what is kidney dialysis

Answer 48

Kidney dialysis is a medical treatment that involves using a machine to filter waste products and excess fluids from the blood when the kidneys are no longer able to do so.

Question 49

describe kidney dialysis and a treatment for kidney failure

Answer 49

During the treatment, the patient’s blood is pumped through a special filter, called a dialyzer, which removes waste products and excess fluids from the blood. The cleaned blood is then returned to the body. Dialysis is typically done regularly to keep dissolved substances at right concentrations, and do remove waste.

Dialysis fluid has the same concentration of salts and glucose as blood plasma, which aren’t removed from the blood.

Barrier is also permeable to ions and waste substances , but not to proteins like membranes in kidney. Waste substances, such as urea, plus excess ions and water from blood move across membrane into dialysis fluid. Cells and proteins stay in blood

Question 50

describe organ donation as a treatment for kidney failure

Answer 50

A kidney transplant is a surgical procedure in which a healthy kidney from a donor is transplanted into the patient’s body to replace the failed kidney. The donor may be a living or donor. A successful kidney transplant can provide the patient with better quality of life, and can potentially eliminate the need for dialysis.

However body is still able to reject, to prevent this:

Kidneys with tissues which are a closely matched type are donated.
Patients with drugs that suppress the immune system, so the body does not reject the kidney.

Question 51

what is urea

Answer 51

Urea is produced from the breakdown of excess amino acids in the liver.