Paper 2: Section 7- Animal coordination, control and homeostasis Flashcards
What is a hormone?
A chemical messenger produced in glands and carried by the blood to the target organ.
What are glands?
An organ or tissue that makes a substance for release, such as a hormone.
What is a target organ?
The organ with receptor molecules on its cell surfaces which recognise a specific hormone.
What is the pituitary gland and where is it located?
An endocrine gland that is located in the brain and is known as a ‘master gland’. It controlls the water content of the blood.
What hormone does the pituitary gland release? What are the effects?
ADH- Increases reabsorption of water by the collecting ducts.
What is the pituitary glands target organ?
The kidneys
What is the thyroid gland and where is it located?
Gland located at the base of the neck which controls metabolic rate.
What hormone does the thyroid gland release? What are the effects?
Thyroxine
- Controls the body’s metabolism
- Plays an important role in growth and development
What is negative feedback?
A mechanism where changes to conditions cause an action to reverse the change, to keep conditions stable.
What is the negative feedback mechanism?
Mechanism to lower raised levels of something, and to raise reduced levels of something.
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.
- hypothalamus
- R
- TSH
- blood
- inhibits
- production
What is the pancrease and where is it located?
Large gland located in the abdomen which controlls blood glucose levels.
What hormone does the pancrease release? What are the effects?
Insulin- Increases the conversion of glucose into glycogen for storage.
What is the pancreases target organ?
The liver.
What are the adrenal glands and where are they located?
Glands located on top of the kidneys which prepare for ‘fight or flight’.
What hormone do the adrenal glands release? What are the effects?
Adrenaline (prapers for flight and flight)
- Increases the breathing and heart rate
- Increases flow of blood to muscles
- Converts glycogen to glucose
What are the adrenal glands target organs?
Several targets including organs in the respiratory and circulatory systems.
What are the ovaries ?
The female reproductive organ.
What hormone do the ovaries produce?
Oestrogen.
What are the testes?
The male reproductive system.
What hormone do the testes produce?
Testosterone.
What is the menstrual cycle?
The recurring series of events in the human female reproductive system, taking around 28 days.
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 ___________.
- uterus
- fertilised
- shed
- menstruation
What part does FSH play in the menstrual cycle?
The FSH causes the maturation of an egg (stimulating oestrogen production and the growth of follicles) in the ovary.
What part does LH play in the menstrual cycle?
LH triggers the release of the egg (ovulation).
What part does oestrogen play in the menstrual cycle?
Oestrogen is involved in repairing and thickening the uterus lining, and stopping FSH from being produced.
. Also simulating the release of LH.
What part does progesterone play in the menstrual cycle?
Maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy
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 __.
- increases
- 12
- same
- 14
- 28
- 13
- increase
- 21
The oral contraceptive (the pill), contains oestrogen or progesterone. How do these hormones prevent pregnancies?
Oestrogen or progesteron prevent the production of FSH, so eggs cannot mature.
What are the benefits of hormonal contraception?
. 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.
What are the risks of hormonal contraception?
. Changes in weight, mood and blood pressure due to high levels of oestrogen.
What non- hormonal methods are available?
. 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
What are the benefits of non-hormonal contraception?
. 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
What are the risks of non-hormonal contraception?
. 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.
What is Assisted Reproductive
Technology (ART) including IVF and clomifene therapy
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.
What is IVF?
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.
What are the avantages of IVF?
. 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.
What are the disavantages of IVF?
. 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.
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.
- ethical
- designer
- fertilised eggs
- destroyed
What is clomifene therapy?
Fertility drug used to stimulate ovulation (egg release).
What is the role of homeostasis throughout the body?
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
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.
- catalyse
- conditions
- nervous
- endocrine
- effectors
When the temperature falls below 37°C how does the body respond?
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
When the temperature goes above 37°C how does the body respond?
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
