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Biology Paper 2 > Topic 7 - Animal coordination, control and homeostasis > Flashcards

Topic 7 - Animal coordination, control and homeostasis Flashcards

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1
Q

Where are hormones produced and transported around the body

A
  • Hormones produced by ENDOCRINE glands, released into blood
  • travel around body in blood until reaching target organ
  • hormone causes target organ to respond, eg by releasing another chemical substance
  • different hormones, different target organs, different responses
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2
Q

Describe all the hormones and their target organs

A

TRH and CRH - pituary gland
TSH - thyroid gland
ADH - kidney
FSH and LH - ovaries
INSULIN and GLUCAGON - liver, muscle and adipose tissue
ADRENALIN - various organs, eg heart, liver, skin
PROGESTERONE - uterus
OESTROGEN - ovaries, uterus, pituary gland
TESTOSTERONE - male reproductive organs

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3
Q

Explain the main differences between hormones and nerve impulses

A

HORMONES:

  • chemical signal
  • transported in bloodstream
  • cells in particular tissues (more specific)
  • slow
  • long duration

NERVES:

  • electrical signal
  • transmission between/through nerve cells
  • muscles or glands
  • very rapid
  • short duration
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4
Q

Explain the effects of adrenalin and what its in response to

A

—> ADRENALIN released from adrenal glands, response to stress. Causes fight or flight

Effects:

  • increases heart rate
  • constricts some blood vessels, make blood pressure higher
  • dilates other blood vessels, increases blood flow to muscles
  • causes liver to convert glycogen -> glucose, which is released into the blood
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5
Q

Explain what thyroxine controls and how it controls it

A

—> THYROXINE controls metabolic rate (rate of cells respire - rate of energy transfers)

How it controls metabolic rate:

  1. low levels stimulates TRH production in hypothalamus
  2. causes TSH release from pituitary gland
  3. TSH acts on thyroid to produce thyroxine
  4. when normal levels thyroxine stops the release of TRH and the production of TSH
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6
Q

Describe the stages in the menstrual cycle

A

MENSTRUATION - break down of uterus lining - begins on day 1 of the cycle and usually lasts about 5 days

second week - the lining of the uterus is gradually built up

OVULATION - release of egg from ovary - day 14

Days 14 to 16 - fertilisation most likely

lining continues to build up - weeks 3 and 4

If fertilisation occurs, uterus lining is maintained and menstruation doesn’t happen

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7
Q

Which two hormones control the menstrual cycle and their roles and where are they produced

A

OESTROGEN - causes growth and repair of lining of uterus wall. Oestrogen inhibits FSH, produced in the ovaries

PROGESTERONE - produced by adrenal cortex, ovaries and testes. triggers lining to thicken

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8
Q

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

A
  1. FSH secreted from pituitary gland, causes a follicle in ovary to mature
  2. As matures, secretes oestrogen which inhibits FSH and starts thickening lining
  3. high concentration of oestrogen —> surge in LH from pituitary
  4. ovulation caused when egg is released from follicle
  5. ruptured follicle becomes a corpus luteum - secretes progesterone, oestrogen - cause more thickening of lining
  6. Progesterone inhibits FSH and LH. If egg isnt fertilised —> corpus luteum breaks down, progesterone concentration falls
  7. triggers menstruation, FSH not inhibited, can be secreted from pituitary gland
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9
Q

Explain the two types of contraception

A

HORMONAL - releasing hormones to prevent ovulation, thicken mucus at the cervix, preventing sperm
Eg :
Hormone pills, implants or injections

BARRIER - stops sperm reaching egg
Eg :
Male and female condoms, the diaphragm, caps and sponges

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10
Q

Give one advantage and one disadvantage of hormonal contraceptives compared with condoms

A

Hormonal contraceptives more effective than condoms ( >99%) at preventing pregnancy.

condoms protect STD’s, hormonal contraceptives do not

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11
Q

Explain how fertility drugs can be used to help fertility

A

CLOMIFENE can be used to cause + FSH and LH

  1. Fertility drug given to stimulate eggs to mature
  2. Eggs taken from ovaries
  3. Eggs + sperm in dish for fertilisation
  4. Fertilised eggs —> embryos
  5. When embryos are tiny balls of cells, one or two placed in mothers womb to develop
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12
Q

Define IVF (in-vitro fertilisation)

A

Fertilisation outside a woman’s body

Offered to those with conceiving problems

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13
Q

Follicle-stimulating hormone (FSH) is used to stimulate ovulation in a woman undergoing IVF treatment, even if she ovulates naturally, explain why. (2 marks)

A

stimulate the maturation of many eggs. Normally only one egg would mature in a normal cycle.

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14
Q

What is an advantage of using FSH in IVF treatment

A

Stimulating more eggs -> more embryos can be produced.

means enough embryos for woman to undergo several cycles if necessary

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15
Q

Explain homeostasis

A

Maintains conditions in body, constant level, response to internal/external change.

NEGATIVE FEEDBACK mechanisms respond change, help restore normal level

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16
Q

Define the relationship between thermoregulation and body temperature

A

THERMOREGULATION keeps core body temperature steady (around 37 degrees)

Controlled by hypothalamus (Thermoregulatory centre monitors and controls temp) , triggers change in skin and muscles

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17
Q

What corrections does the body make to a hot temperature environment

A

INCREASES energy transferred to surroundings by:

  • changes triggered - blood flow so more blood flows near skin surface (dilate or constrict to change blood flow)
  • sweat glands release more sweat onto skin surface to evaporate
  • sebaceous glands produce oil that helps sweat spread out on skin
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18
Q

What corrections does the body make to a cold temperature environment

A

REDUCES energy transferred -> surroundings by:

  • less blood near surface
  • sweat stopped produced by glands
  • body hairs raised by erector muscles in skin (goosebumps)
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19
Q

Explain why its important for the enzymes in our bodies that our internal temperature is fairly constant (2 marks)

A

Enzymes work fastest @ optimum

lower or higher, aren’t active, chemical reactions arent carried out as normal, causing harm to body

20
Q

Define osmoregulation and its effect on animal cells

A

Controls amount water lost in urine, controls amount water in body

Stops animal cells swelling up/shrinking by osmosis if body water content changes

21
Q

Explain the structure of the skin in thermoregulation

A

Vasodilation/vasoconstriction changes blood flow in surface capillaries depending on temperature in dermis

Sweat glands in dermis release sweat when warm to lose heat through evaporation

hair muscle contracts when cold to pull hairs upright, trapping layer of air, when warm hairs lie flat

22
Q

Describe the role of the dermis and epidermis of the skin in cooling the body (4 marks)

A

Sweat glands in the dermis secrete sweat on to the epidermis. This evaporates, cooling the body down.

Muscles in dermis relax, hairs can lie flat. there is thinner layer of insulating air trapped against epidermis

23
Q

Explain and describe vasoconstriction and the structure when a cold temperature is detected

A

More blood flows through deep skin blood vessels so less blood flows through surface capillaries

This keeps warm blood deeper in the skin so less heat is transferred to air. Little heat loss from skin

24
Q

Explain and describe vasodilation and the structure when a hot temperature is detected

A

Less blood flows through deep skin blood vessels and more blood flows through surface capillaries.

This increases heat loss by radiation

Increases blood flow of warm blood near skin so heat can transfer easily to air

25
Q

Explain how shivering affects body temperature when a cold environment is detected

A

Muscles quickly contract and relax in succession (causing shivering) releasing energy to warm the body

26
Q

Describe osmoregulation in terms of a negative feedback system (3 marks)

A

If there is too much water in the body this means that more water is excreted in urine. If there isn’t enough water then less water is excreted in urine, helping to increase water levels again. This is an example of negative feedback because the body works to restore the balance

27
Q

A pale skinned person may look pink after exercise.

Identify what causes this change (1 mark)

Describe and explain what effect this has on body temperature (2 marks)

A

They look pink because more blood is flowing near the surface of the skin as a result of vasodilation (1)

This increases the rate of transfer of heat energy from the body to the environment and so reduces body temperatures

28
Q

Explain how the hormone insulin controls blood glucose concentration

A

If the blood glucose concentration is too high, the pancreas produces the hormone insulin, this causes glucose to move from the blood into the cells.

In liver and muscle cells excess glucose is converted to glycogen for storage

Insulin controls the storage of glycogen in your liver and muscles

29
Q

Explain how blood glucose concentration is regulated by glucagon

A

When blood glucose levels fall, the pancreas releases glucagon

This causes your liver to break down the glycogen back into glucose

30
Q

Explain the importance of glucose and pancreas

A

GLUCOSE is vital for respiration, allowing the body to release energy

The PANCREAS monitors and controls blood glucose concentration using insulin and glucagon

31
Q

Explain the effect of low glucose on the pancreas, liver and blood glucose levels

A

PANCREAS - insulin not secreted into the blood

LIVER - doesn’t convert glucose into glycogen

BLOOD GLUCOSE LEVEL - Increases

32
Q

Explain the effect of high glucose on the pancreas, liver and blood glucose levels

A

PANCREAS - insulin secreted into the blood

LIVER - converts glucose into glycogen

BLOOD GLUCOSE LEVEL - decreases

33
Q

Explain the cause of type 1 diabetes

A

Caused when the immune system has damaged the persons insulin-secreting pancreatic cells, person doesn’t produce INSULIN

34
Q

Explain how type 1 diabetes can be controlled

A

Inject insulin into the fat below the skin

They have to work out the right amount of insulin to inject so that the blood glucose concentration is kept within safe limits

35
Q

Explain the cause of type 2 diabetes

A

Person doesn’t produce enough insulin but their liver and muscle cells have become RESISTANT to it

36
Q

Explain how type 2 diabetes can be controlled

A

Most people eat less sugary foods and exercise

Medication can be used if needed

37
Q

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

A

Measurements of fat, estimations used:

  1. BMI : mass (kg) / height^2 (m)
    (Assumes that the mass of the body tissues is in proportion to height)
  2. Fat closely linked to cardiovascular disease is abdominal fat

Divide waist by hip measurement to get waist:hip ratio

38
Q

Describe the structure of the urinary system

A

RENAL VEINS - carry cleaned blood back to the body

URETERS carry URINE from the kidneys to the bladder

BLADDER stores urine

Urine flows through the URETHRA to the outside of the body

RENAL ARTERIES carry blood from the body to the kidneys

KIDNEYS remove substances (urea) from blood and makes urine

A muscle keeps the exit from the bladder closed until we decide to urinate

39
Q

What is the difference between urea and urine, and the ureter and urethra

A

Urea is produced from the breakdown of excess amino acids in the liver, its toxic in excess however urine contains urea, water and salts.

Ureters are tube-like structures that connect the kidneys with the urinary bladder however urethra is a tube that connects the urinary bladder to the outside of the body

40
Q

Explain how the structure of the nephron is related to its function in filtration in the glomerulus and Bowman’s capsule

A

Filtration of small molecules from blood into tubule, including water, glucose, salts and urea in the glomerulus and bowmans capsule

Glomerulus - small knot of capillaries
Bowman’s capsule - cup shaped

41
Q

Explain how the structure of the nephron is related to its function in selective reabsorption of glucose

A

Selective reabsorption of glucose from tubule back into blood by active transport

(Selective reabsorption - useful molecules absorbed back into blood, other molecules left in tubule)

42
Q

Explain how the structure of the nephron is related to its function in reabsorption of water

A

Reabsorption of water that the body needs from the tubule back into the blood (osmoregulation)

This happens in the COLLECTING DUCT

43
Q

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

A

ADH - increases permeability of cell membranes in collecting duct of nephron

So more water reabsorbed from urine by osmosis

44
Q

Explain the function of the hormone ADH

A

Amount of water reabsorbed from the nephrons is controlled by ADH (Antidiuretic hormone)

Regulates water content of blood (osmoregulation)

45
Q

Explain what is meant by a negative feedback mechanism, using ADH production as a example (4 marks)

A

As increase in blood water content causes the pituitary gland to secrete less ADH. This causes less water to be reabsorbed by the collecting duct in the kidneys so more water is excreted by kidneys. A decrease in blood water content causes the pituitary gland to secrete more ADH, which causes less water to be excreted by the kidneys. This is a negative feedback mechanism because a change in blood water content causes an opposite change that restores the ‘normal’ blood water content

46
Q

Describe kidney dialysis as a treatment for kidney failure

A

KIDNEY FAILURE is when it stops working so excess water, mineral ions and urea build up

KIDNEY DIALYSIS is carried out every 2 or 3 days

It uses diffusion which restores which restores normal dissolved substance concentrations in the blood.
Urea then diffuses out of the blood into the dialysis fluid
Dialysis fluid contains the same concentration of useful substances as blood so glucose and mineral ions aren’t lost

47
Q

Describe kidney transplant as a treatment for kidney failure

A

Healthy kidney connected to blood circulation to replace

PROBLEMS :
Antigens on transplanted kidney cells different to patients. Antibodies in patient attack kidney and reject it

PREVENTING REJECTION:

  • antigens must be as similar as possible
  • drugs for life to reduce effects of immune system (patient may get more infections than usual)

Biology Paper 2 (4 decks)

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