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gcse biology > topic 7: animal coordination and homeostasis > Flashcards

topic 7: animal coordination and homeostasis Flashcards

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1
Q

what is a hormone

A

a chemical messenger secreted by a gland, they travel through the bloodstream to targeted organs, though they are slower acting that electrical impulses they are longer lasting.

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2
Q

what are the two hormones responsible for controlling blood glucose

A

insulin-decreases blood glucose by encouraging the liver to turn glucose into glycogen stores

glucagon- signals the liver to break down glycogen back into glucose for respiration

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3
Q

how do contraceptive pills stop women getting pregnant

A

contains progesterone that inhibits the production of LH and FSH making an egg unable to grow in the uterus

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4
Q

what hormone causes the lining of the uterus to thicken

A

oestrogen

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5
Q

what is a disadvantage of treating infertility with hormone treatment

A

increase’s complications and there is a likelihood of more that one birth

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6
Q

what is metabolic rate

A

the rate at which energy stored in your food is transferred by all the reactions that take place in your body to keep you alive

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7
Q

what is adrenalin do and what are its effects (target organs include heart, muscles and liver)

A

.binds to receptors in the heart, making it contract more frequently and increase overall heart rate

.increases blood flow to muscles allowing cells to receive more oxygen and glucose for respiration

.adrenaline binds to liver and causes it to break glycogen stores into glucose for respiration

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8
Q

how does thyroxine control metabolic rate (when levels are low)

A

.low levels of thyroxine stimulate the hypothalamus to release TRH

.TRH stimulates the pituitary gland to release TSH

.TSH stimulates the thyroid gland to release thyroxine, causing thyroxine levels to rise again

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9
Q

how does thyroxine control metabolic rate (when levels are too high)

A

.higher than normal levels of thyroxine inhibit the production of TRH

.low levels of TRH inhibit production of TSH which cause thyroxine levels to drop

.thyroxine levels get lower as a result of negative feedback

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10
Q

what are the 4 physical stages of the menstrual cycle

A

stage 1: menstruation starts the lining of the uterus breaks down and is released

stage 2: the uterus lining is repaired from day 4-14 and thickens in preparation for a fertilised egg

stage 3: egg develops and is released by ovaries

stage 4: if no egg is fertilised the spongy lining begins to breakdown by day 28 and the cycle repeats.

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11
Q

what are the hormonal stages of the menstrual cycle

A

FSH: released by the pituitary causes a follicle to mature in the ovaries and stimulates oestrogen

Oestrogen: released by the ovaries, thickens the uterus lining and stimulates LH surge at high levels

LH: released by the pituitary gland LH stimulates ovulation where the follicle ruptures and an egg is released

the remains turns into a corpus luteum which secrets progesterone

Progesterone: released by corpus luteum after ovulation, maintains the lining and inhibits FSH and LH.
When progesterone levels drop oestrogen gets low and so the uterus lining of the uterus falls.

low progesterone stimulates FSH and the cycle repeats

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12
Q

what are the 5 types of hormonal contraceptives

A

IUD
combined pill
progesterone only pill
contraception patch
contraceptive implant

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13
Q

how does the combined pill work

A

oestrogen: stimulates thick mucus preventing sperm from reaching the egg

progesterone: inhibits the production of FSH meaning no egg is released

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14
Q

how does the contraceptive implant work

A

slowly releases progesterone for up to 3 years

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15
Q

how does the IUD work

A

implanted into the uterus
releases progesterone

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16
Q

describe the process of IVF

A

.women are given FSH and LH to stimulate egg maturation

.eggs are collected and fertilised outside the body

.eggs are placed in a incubator to grow into embryo

.some are reinserted back into the mother uterus to grow

17
Q

pros and cons of IVF

A

pros: allows for infertile couples

cons: doesn’t always work
stressful and upsetting
often leads to multiple births which could lead to still births

18
Q

why is thermoregulation so important

A

to maintain an optimum temperature for enzyme activity, with an optimum of (37), if temp drops the enzyme activity will slow down, if they get too high they might denature

19
Q

what does the body do when temperature is too hot

A

.erector muscles relax so hairs lie flat

.sweat forms on the top of the skin, when it evaporates thermal energy is removed from the body

.blood vessels close to the surface of skin dilate to allow more blood to flow near the surface to transfer energy out into the surroundings

20
Q
A
21
Q

what does the body do when temperatures are too low

A

.erector muscles stand up to trap an insulating layer of air

.little sweat is produced to reduce heat energy transfer

.blood vessels near the skin surface restrict to reduce energy transferred to the surroundings

.shivering allow muscle to contract increasing rate of respiration and more energy

22
Q

what role does the hypothalamus have in thermoregulation

A

contains receptors that are sensitive to the blood temperature in the brain
receives impulses from receptors in the skin that give information on external temperatures, located in the epidermis and the dermis

23
Q

what is the epidermis

A

outer layer of the skin

24
Q

what is the dermis

A

deeper layer of the skin below the epidermis

25
Q

what causes type 1 diabetes

A

when pancreatic cells do not produce insulin because cells have been destroyed by the body’s immune system

26
Q

how is type 1 diabetes controlled

A

insulin injections

27
Q

how does type 2 diabetes occur

A

when insulin producing cells do not produce enough insulin or organs do not respond properly to the insulin produced

28
Q

how to treat type 2 diabetes

A

.eating healthier or reducing amount of sugar in diet
.increasing physical activity
.

29
Q

treatments of kidney failure

A

kidney transplants
kidney dialysis-takes over the function of the kidneys

30
Q

what is homeostasis

A

the maintenance of a constant internal environment

31
Q

what 3 controlled conditions are in homeostasis

A

-blood glucose levels
-osmoregulation
-thermoregulation

32
Q

what are the 3 functions of the kidneys

A

-remove urea
-controlling iron content
-controlling water content

33
Q

describe ultrafiltration

A

.blood enters the kidneys at high pressures
.water, ions, urea, sugar are squeezed out into the capsule at the start of the nephron

34
Q

describe reabsorption

A

.as substances flow through the nephron substances are reabsorbed
.all sugars through active transport
.some ions through active transport
.some water decided by ADH

35
Q

describe release of waste

A

useless or harmful stuff (urea) is released as urine

36
Q

symptoms of diabetes

A

.fatigue, need to urinate a lot, weight loss, hunger, blurry vision, thirsty

37
Q

what are the 5 features of most exchange surfaces and an explanation as to why they are beneficial

A

Feature 1 - Large surface area

Explanation 1 - Lots of molecules can diffuse across at the same time

Feature 2 - Surfaces are very thin

Explanation 2 - Substances only have to diffuse a short distance

Feature 3 - Surfaces are permeable

Explanation 3 - Substances are able to pass through the surface

Feature 4 - Good blood supply (good supply of ‘internal medium’)

Explanation 4 - Maintains a strong concentration gradient as blood is constantly replaced

Feature 5 - Good supply of ‘external medium’

Explanation 5 - Maintains a strong concentration gradient as the air or food etc is constantly replaced

38
Q

features and why alvioli are well suited

A

Feature 1 - There are lots of alveoli, giving a large total surface area

Explanation 1 - Lots of molecules can diffuse across at the same time

Feature 2 - Surfaces are very thin (only 1 alveolar cell and 1 capillary cell thick)

Explanation 2 - Substances only have to diffuse a short distance

Feature 3 - Surfaces are permeable

Explanation 3 - Oxygen and carbon dioxide are able to diffuse across

Feature 4 - Good blood supply (good supply of ‘internal medium’)

Explanation 4 - Maintains a strong concentration gradient as blood is constantly replaced

Feature 5 - Good supply of air ( good supply of ‘external medium’)

Explanation 5 - Maintains a strong concentration gradient as the air in the alveoli is constantly replaced with new oxygen rich air from the atmosphere

gcse biology (13 decks)

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