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GCSE Biology > Paper 2: Section 7- Animal coordination, control and homeostasis > Flashcards

Paper 2: Section 7- Animal coordination, control and homeostasis Flashcards

1
Q

What is a hormone?

A

A chemical messenger produced in glands and carried by the blood to the target organ.

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2
Q

What are glands?

A

An organ or tissue that makes a substance for release, such as a hormone.

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3
Q

What is a target organ?

A

The organ with receptor molecules on its cell surfaces which recognise a specific hormone.

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4
Q

What is the pituitary gland and where is it located?

A

An endocrine gland that is located in the brain and is known as a ‘master gland’. It controlls the water content of the blood.

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5
Q

What hormone does the pituitary gland release? What are the effects?

A

ADH- Increases reabsorption of water by the collecting ducts.

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6
Q

What is the pituitary glands target organ?

A

The kidneys

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7
Q

What is the thyroid gland and where is it located?

A

Gland located at the base of the neck which controls metabolic rate.

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8
Q

What hormone does the thyroid gland release? What are the effects?

A

Thyroxine
- Controls the body’s metabolism
- Plays an important role in growth and development

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9
Q

What is negative feedback?

A

A mechanism where changes to conditions cause an action to reverse the change, to keep conditions stable.

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10
Q

What is the negative feedback mechanism?

A

Mechanism to lower raised levels of something, and to raise reduced levels of something.

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11
Q

Low thyroxine levels in the bloodstream stimulate the ____________ to release T_H, causing the pituitary to release ___. This way the thyroid releases more thyroxine and _____ levels return to normal. When thyroxine levels are normal thyroxine _______ the release of TRH and the _________ of TSH.

A
  1. hypothalamus
  2. R
  3. TSH
  4. blood
  5. inhibits
  6. production
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12
Q

What is the pancrease and where is it located?

A

Large gland located in the abdomen which controlls blood glucose levels.

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13
Q

What hormone does the pancrease release? What are the effects?

A

Insulin- Increases the conversion of glucose into glycogen for storage.

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14
Q

What is the pancreases target organ?

A

The liver.

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15
Q

What are the adrenal glands and where are they located?

A

Glands located on top of the kidneys which prepare for ‘fight or flight’.

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16
Q

What hormone do the adrenal glands release? What are the effects?

A

Adrenaline (prapers for flight and flight)
- Increases the breathing and heart rate
- Increases flow of blood to muscles
- Converts glycogen to glucose

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17
Q

What are the adrenal glands target organs?

A

Several targets including organs in the respiratory and circulatory systems.

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18
Q

What are the ovaries ?

A

The female reproductive organ.

19
Q

What hormone do the ovaries produce?

A

Oestrogen.

20
Q

What are the testes?

A

The male reproductive system.

21
Q

What hormone do the testes produce?

A

Testosterone.

22
Q

What is the menstrual cycle?

A

The recurring series of events in the human female reproductive system, taking around 28 days.

23
Q

During the menstrual cycle, the lining of the ______ is prepared for pregnancy. If the implantation of the ________ egg into the uterus lining does not happen, the lining is then ____. This is known as ___________.

A
  1. uterus
  2. fertilised
  3. shed
  4. menstruation
24
Q

What part does FSH play in the menstrual cycle?

A

The FSH causes the maturation of an egg (stimulating oestrogen production and the growth of follicles) in the ovary.

25
Q

What part does LH play in the menstrual cycle?

A

LH triggers the release of the egg (ovulation).

26
Q

What part does oestrogen play in the menstrual cycle?

A

Oestrogen is involved in repairing and thickening the uterus lining, and stopping FSH from being produced.
. Also simulating the release of LH.

27
Q

What part does progesterone play in the menstrual cycle?

A

Maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy

28
Q

Days 1 to 12 - oestrogen gradually ________ and peaks approximately on the __th day. Progesterone, LH and FSH stay approximately at the ____ levels and begin to increase slightly from around day 12.

FSH and LH patterns are very similar and peak during ovulation at approximately __ days during this cycle. They drop sharply on day 15 and stay constant until day 28.

Oestrogen drops during days __ and 14, and progesterone continues to gradually ________ until about day 21, when it slowly beings to decrease again. Oestrogen mirrors this shape and also has a second lower peak at about day __.

A
  1. increases
  2. 12
  3. same
  4. 14
  5. 28
  6. 13
  7. increase
  8. 21
29
Q

The oral contraceptive (the pill), contains oestrogen or progesterone. How do these hormones prevent pregnancies?

A

Oestrogen or progesteron prevent the production of FSH, so eggs cannot mature.

30
Q

What are the benefits of hormonal contraception?

A

. More than 99% effective if taken correctly . Can reduce the risk of certain cancers.
. Contraceptive injections, implants or skin patches contain slow release progesterone to prevent the maturation and release of eggs.

31
Q

What are the risks of hormonal contraception?

A

. Changes in weight, mood and blood pressure due to high levels of oestrogen.

32
Q

What non- hormonal methods are available?

A

. Condoms and diaphragms, which prevent the sperm reaching an egg
. IUD’s (also known as a coil) prevent the implantation of an embryo or release of a hormone
. Spermicidal agents which kill or disable sperm
. Abstaining from intercourse when an egg may be in the oviduct
. Surgical methods of male and female sterilisation, eg a vasectomy, where the sperm ducts are cut and tied

33
Q

What are the benefits of non-hormonal contraception?

A

. Condoms are easy and quick to use
. IUDs can remain in position for up to 10 years.
. Spermicidal agents can be added to other physical barriers such as condoms
. Abstaining can be used successfully

34
Q

What are the risks of non-hormonal contraception?

A

. Condoms sometimes can tear or rip.
. Diaphragms need to be put in just before sex and left in several hours afterwards.
. IUDs need to be fitted by a health professional and there is a small risk of causing an ectopic pregnancy, which leads to complications for both the mother and the foetus.
. Spermicidal agents can cause allergic reactions for some.
. If the timings are not accurate when abstaining, the chance of pregnancy is high.
. Surgical methods cannot be reversed, and is considered permanent.

35
Q

What is Assisted Reproductive
Technology (ART) including IVF and clomifene therapy

A

Assisted Reproductive Technology is the use of hormones and procedures, as fertility treatments, to help to achieve pregnancy. These include in vitro fertilisation (IVF) and a fertility drug, clomifene.

36
Q

What is IVF?

A

This involves bringing the sperm and the egg together to create an embryo, which is placed into the woman’s womb to increase the chance of giving birth.

37
Q

What are the avantages of IVF?

A

. Allows people to have babies of their own
. It has a safe track record and has been used since 1978
. The embryos can be screened for genetic diseases
. Only unaffected embryos are used
. Unused eggs can be used for research or donated to other couples.

38
Q

What are the disavantages of IVF?

A

. There are side effects from the drugs used, such as hot flushes and severe headaches.
. There is a possibility of multiple births, which is dangerous for mother and babies.
. OHS, when too many eggs develop in the ovaries.
. It is very emotionally and physically stressful.
. The success rates are not high.

39
Q

Some people worry about the _____ implications of IVF. They are concerned that couples may want ‘________ babies’ with ‘desirable’ qualities, so may only want certain ________ eggs. For example, they may want a girl if they have lots of boys in the family.

Also, the embryos that are not used may be ________. Some people might view these as new lives, so may consider destroying them to be unethical.

A
  1. ethical
  2. designer
  3. fertilised eggs
  4. destroyed
40
Q

What is clomifene therapy?

A

Fertility drug used to stimulate ovulation (egg release).

41
Q

What is the role of homeostasis throughout the body?

A

Homeostasis maintains optimal conditions for enzyme action , as well as all cell functions.
It is the maintenance of a constant internal environment despite changes in internal and external conditions

42
Q

Homeostasis is important seeing as enzymes are proteins that _______ vital chemical reactions inside the body. Enzymes only function properly under certain __________, such as preferred pH and temperature. If not under these conditions, this could cause the organism to die. Homeostasis relies on automatic control systems that include the _______ system or chemical responses (_________ system). Receptors and __________ are also needed.

A
  1. catalyse
  2. conditions
  3. nervous
  4. endocrine
  5. effectors
43
Q

When the temperature falls below 37°C how does the body respond?

A

It sends nerve impulses to effectors, the skin and muscles, to cause:
. shivering
. vasoconstriction in blood vessels that supply skin capillaries with blood - this reduces blood flow near the skin’s surface and reduces heat loss
. erector muscles in hair follicles to contract causing hairs to stand on end and trap warm air next to the skin
. sweat glands to stop secreting sweat

44
Q

When the temperature goes above 37°C how does the body respond?

A

Then the muscles and skin receive signals to cause:
. shivering to stop
. vasodilation to happen to increase blood flow near the skin’s surface and increase heat loss
. erector muscles in hair follicles to relax, releasing any warm air trapped next to the skin
. sweat gland to start secreting sweat, which will evaporate from the surface of the skin, removing heat energy

GCSE Biology (18 decks)

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