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GCSE B3 > 2. Homeostasis Pt6 > Flashcards

2. Homeostasis Pt6 Flashcards

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1
Q

What forms can contraceptives come in?

A

-pills
-implant
-patch
(Hormonal or non-hormonal)

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2
Q

How do oral contraceptives work?

A
  • they prevent women from becoming pregnant
  • most contained oestrogen &/or progesterone as they inhibit FSH production and so stop an egg from maturing in the ovaries
  • they also thicken cervical mucus to prevent stern from getting through
  • some side effects include: high blood pressure & headaches, some new pills contain only progesterone
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3
Q

What are barrier methods and give 2 examples?

A
  • barrier methods prevent the sperm from reaching the egg

- condoms and diaphragms

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4
Q

How do condoms work?

A
  • they cover the penis to collect semen (unless they’re damaged)
  • they also protect against sexually transmitted infections
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5
Q

How do diaphragms work?

A
  • they cover the cervix to stop sperm (must be positioned correctly)
  • they work best with a chemical spermicide to kill sperm
  • they don’t prevent STIs
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6
Q

How do intrauterine devices work?

A
  • IUDs (aka the coil) are inserted into the uterus by a doctor to prevent embryos from implanting o
  • some also release progesterone
  • they usually last for 3-5 years, but may cause infections or period problems
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7
Q

What’s a surgical contraception?

A
  • in men a vasectomy is where the sperm ducts are cut and tied to prevent any sperm getting into the semen
  • in women the oviducts can be cut and tied to prevent eggs reaching the uterus or sperm reaching the egg
  • requires general anaesthetic
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8
Q

What’s abstinence of sex?

A
  • abstaining from sex around ovulation when the eggs is in the oviduct may prevent pregnancy but is very unreliable
  • hormone levels can be tested to indicate when ovulation occurs to improve its effectiveness
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9
Q

What’s an easy way to get pregnant if you can’t conceive?

A
  • Use fertility drugs

- some women can’t conceive because they don’t produce enough of the right hormones

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10
Q

How do fertility drugs work?

A
  • artificially FSH can be taken to stimulate the eggs in the ovary and trigger oestrogen production
  • or LH
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11
Q

Other than the fertility pill what other way can you get pregnant?

A
  • in vitro fertilisation (IVF)
  • fertilisation usually occurs in the oviducts (Fallopian tubes) which carry the egg from the ovaries to the uterus
  • if these are damaged then eggs canning reach the uterus and the woman can’t get pregnant
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12
Q

Explain how in vitro fertilisation (IVF) is carried out?

A
  1. The women is first treated with FSH and LH to stimulate the maturity of several eggs at once
  2. The eggs are collected and placed in a Petri dish
  3. Sperm from the father is mixed in with the eggs to fertilise them
  4. embryos start to develop and are checked to ensure they’re healthy
  5. When they’re small balls of cells 1 or 2 embryos are inserted into the woman’s uterus
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13
Q

What releases adrenaline?

A

Adrenal glands

Located on top of each kidney

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14
Q

When is adrenaline produced?

A
  • it’s released into during stressful, scary or exciting times
  • it triggers a fight or flight response
  • it boosts the oxygen and glucose supply to the brain and muscles to increase respiration to prepare the body for intense activity
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15
Q

What are the responses to adrenaline?

A
  1. Increased heart rate and breathing rate
  2. Glycogen in the liver is converted to glucose for respiration
  3. Mental awareness increases
  4. Blood is diverted from your digestive system to your muscles
  5. Pupils dilate to let in more light
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16
Q

Is the release of adrenaline a negative feedback?

A

No

17
Q

Where and how is thyroxine produced?

A
  • it’s produced by the thyroid gland (in your neck)

- using small amounts if iodine from your diet (and amino acids)

18
Q

What does thyroxine control?

A

the basal metabolic rate of the body (the speed at which chemical reactions in the body take place) such as:
-the rate of respiration, using oxygen to break down substances such as sugars
-the growth and development of a child’s brain
Adults are relatively stable

19
Q

Explain how thyroxine is controlled by a negative feedback loop?

A
  • if the blood thyroxine levels fall, the brain detects the drop and signals the pituitary gland to release Thyroid stimulating hormone (TSH)
  • this stimulates the thyroid gland to release more thyroxine
  • if blood thyroxine levels rise, the brain signals the pituitary gland to stop releasing TSH
20
Q

Why is it important that you control your body temperature?

A
  • it’s important your core body temperature remains at 37 C

- so enzymes work at their optimum rate

21
Q

What detects a change in your body temperature?

A
  • your thermoregulatory centre in your hypothalamus contains receptors to detect changes to the temperature of the blood flow
  • temperature receptors in the skin also detect changes in the external temperature and send information to the thermoregulatory centre
  • these changes trigger negative feedback mechanism
  • some responses are behavioural eg. Standing in the shade
22
Q

What does your body do when it’s too cold?

A
  1. blood vessels (small arteries) supplying the skin constrict, reducing blood flow to the capillaries near the surface
    - called vasoconstriction, it reduces heat loss by radiation
  2. sweat production decreases, reducing heat loss by evaporation
  3. skeletal muscles rapidly contract and relax producing shivering. This generates more heat energy from increased respiration (exothermic reaction)
23
Q

What does your body do when it’s too hot?

A

(Hypothalamus receptor detect increase in temperature)
1. Vasodilation dilate the blood vessels to the skin, allowing more blood to flow to capillaries at the surface, increases heat loss by radiation
2. Sweat production increases, which increases heat loss by evaporation
Both causing energy transfer from the skin to the environment

24
Q

Why would sweating help in humid weather?

A

-because humid slows evaporation, making it difficult to remain cool (the sweat isn’t evaporating)

25
Q

What auxin?

A

-a plant hormone that allows plants to selectively grow parts of the plant to move in certain directions

26
Q

What’s gravitotropism?

A

-it’s a response to gravity
-it ensures that shoots grow up and roots grow down
(Irrelevant to light)

27
Q

What’s phototropism?

A
  • it’s the response to light

- it ensures the the stem bends towards the light to maximise the absorption of light by the leaves for photosynthesis

28
Q

How can you use auxin?

A
  1. rooting powders: it encourages the stem to develop roots to grow a new plant from a cutting
  2. weed killers: it encourages uncontrolled growth in broad leaved plants (weeds) which kills them
    - some can selectively kill weeds but not other plants (eg. Crops)
    - this reduces competition for water, light and nutrients increasing crop yield
  3. Promoting growth in tissue culture
29
Q

How can you use gibberellins?

A

(It causes the stem to make a flower instead of a leaf)

  • promoting flowing: throughout the year for florists
  • increasing fruit size: or triggering fruit development
  • end seed dormancy
30
Q

How can you use ethene with plants?

A
  • it’s used in the food industry to control ripening of fruit during storage and transport
  • then ripened to the perfect stage ready for sale

GCSE B3 (12 decks)

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