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What is homeostasis?
regulation of the internal conditions of a cell or organism to maintain optimum conditions
What conditions are controlled in the human body? (3)
blood glucose concentration
body temperature
water levels
What two types of responses happen in the body to control conditions?
nervous responses or chemical (hormonal) responses
What three parts are present in all control systems?
receptors
coordination centres
effectors
In the body control system: what do cells called receptors do?
detect stimuli
In the body control system: what do coordination centres do?
receive and process information from receptors
Give examples of coordination centres in the human body (3)
the brain, spinal cord and pancreas
In the body control system: what do effectors do?
bring about responses which restore optimum levels of things like glucose and water
Give examples of effectors in the human body
muscles and glands
What is the nervous system?
the body system that includes all of the nerve cells, the brain and the spinal cord
What does the nervous system do?
allows humans to react to their surroundings and coordinate their behaviour
What is the central nervous system?
the brain and spinal cord
What does the central nervous system do?
it coordinates the response of effectors which may be muscles contracting or glands secreting hormones
What is the name given to the part of the nervous system which contains only nerves?
The peripheral nervous system
What happens in the body between a stimulus and a response?
stimulus → receptor → coordinator → effector → response
What is a stimulus?
A change in external environment
What is a reflex action?
An automatic and rapid nervous response which does not require the conscious part of the brain
What is the endocrine system?
the body system that includes hormones and glands
What does the endocrine system do?
sends hormones around the body through the blood
What are hormones produced by?
glands
What are hormones?
chemicals which are carried in the bloodstream. They cause effects to happen in organs.
Which is faster: the nervous system or the hormonal (endocrine) system?
the nervous system
Which effects last longer: the nervous system or the hormonal (endocrine) system?
the hormonal (endocrine) system
What does the pituitary gland do?
Produces many hormones which regulate body conditions. Some of these hormones act on other glands, which produce other hormones.
Where is the pituitary gland?
At the base of the brain
Where is the pancreas?
Behind the stomach.
Where is the thyroid?
Along the front of the windpipe.
Where are the adrenal glands?
One above each kidney.
Where are the ovaries?
In the lower abdomen.
Where are the testes?
In the scrotum.
Where is blood glucose concentration monitored?
In the pancreas
What is carbohydrate broken down into?
Glucose
What happens when blood glucose levels are too high?
• the pancreas produces the hormone insulin
• excess glucose is converted to glycogen for storage.
What is type 1 diabetes?
the pancreas fails to produce sufficient insulin, so blood glucose can reach dangerously high levels
How is type 1 diabetes controlled and treated?
with insulin injections
What is type 2 diabetes?
the body cells no longer respond to insulin produced by the pancreas
How can type 2 diabetes be controlled?
A carbohydrate controlled diet and an exercise regime
Which type of diabetes is obesity a risk factor for?
Type 2 diabetes
What happens at puberty?
reproductive hormones cause secondary sex characteristics to develop
What are the main male and female reproductive hormones?
Male: testosterone
Female: oestrogen
(Oestrogen and testosterone are produced by both sexes).
What is the main role of testosterone?
it stimulates sperm production
Where is oestrogen produced?
In the ovaries
Where is testosterone produced?
In the testes
What four hormones control the menstrual cycle?
FSH, LH, oestrogen and progesterone.
What do FSH and LH stand for?
Follicle-stimulating hormone.
Luteinising hormone.
How many days long is the menstrual cycle (usually)?
28
What is the function of FSH?
causes maturation of an egg in the ovary
What is the function of LH?
stimulates the release of an egg
Which hormones are involved in maintaining the uterus lining?
Oestrogen and progesterone
What is contraception?
hormonal and non-hormonal methods of controlling fertility
List hormonal methods of contraception.
Oral contraceptive pills
Patch
Implant
Injection
The IUD (intrauterine device, or the coil)
List barrier methods of contraception.
Condoms
Diaphragms
How do oral contraceptives control fertility?
they contain hormones to inhibit FSH production so that no eggs mature
How do injections, implants or skin patches control fertility?
they slowly release progesterone to inhibit the maturation and release of eggs for a number of months or years
How do barrier methods control fertility?
they prevent the sperm reaching an egg
How do intrauterine devices control fertility?
they prevent the implantation of an embryo or release a hormone
How do spermicidal agents control fertility?
they kill or disable sperm
How does abstaining from intercourse control fertility?
this tries to make sure there are no sperm in the female reproductive system when an egg may be in the oviduct
How do surgical methods control fertility?
they prevent the sperm reaching an egg by removing tubes in the reproductive systems
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