B5 Homeostasis

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

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)

brain

spinal cord

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 (2)

muscles

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?

coordinates the response of effectors like 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 doesn’t 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? (2)

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? (2)

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? (2)

the pancreas produces the hormone insulin

excess glucose is converted to glycogen for storage

What is type 1 diabetes? (2)

the pancreas fails to produce sufficient insulin

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? (2)

carbohydrate controlled diet

exercise regime

Which type of diabetes is obesity a risk factor for?

Type 2

What happens at puberty?

reproductive hormones cause secondary sex characteristics to develop

What are the main male and female reproductive hormones? (2)

M: testosterone

F: 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

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? (2)

Oestrogen

progesterone

What is contraception?

hormonal and non-hormonal methods of controlling fertility

List hormonal methods of contraception (5)

Oral contraceptive pills

Patch

Implant

Injection

The IUD (intrauterine device, or the coil)

List barrier methods of contraception (2)

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