Foundation: B5 - Homeostasis Flashcards
What is homeostasis?
The maintenence of internal conditions
What three things are maintained in the human body?
blood glucose concentration
body temperature
water levels
What do all control systems include:
receptors, coordination centres, effectors
What is the importance of the nervous system in humans?
It allows humans to react to their surroundings and to coordinate their behaviour
What is the central nervous system (CNS) made up of?
Brain and spinal cord
What is a stimulus?
A change in the environment, eg. temperature change
Why are reflex actions important?
They are automatic and rapid, they do not involve the consious part of the brain. They help to keep us safe from harm.
What is the endocrine system made of?
Glands, hormones, bloodstream, target organs
What are hormones?
Chemical messengers
Which gland is considered to be the ‘master gland’?
The pituitary gland
Compare the action of the nervous system to the action of the endorcrine system.
Nervous system: messages travel as electrical impluses, faster response, shorter effect on the body.
Endocrine system: messages travel as chemical messengers, slower response, longer effect on the body.
How do messages travel in the nervous system?
As electrical impluses through neurons.
Which hormone reduces the concentration of glucose in the blood?
Insulin
Which organ releases insulin?
The pancreas
When is insulin released from the pancreas?
When the blood glucose concentration is too high.
What effect does insulin have on blood glucose?
It causes glucose to be converted into glycogen to be stored in the liver or muscles.
What is type 1 diabetes?
A disorder which a person is born with. The pancreas does not produce insulin and is treated with insulin injections.
What is type 2 diabetes?
A disorder which a person develops due to poor diet. The body stops responding to insulin. It is treated with a carbohydrate-controlled diet & exercise plan.
What are the main male & female reproductive hormones?
Males: testosterone
Females: oestrogen
What are the three main hormones involved in the menstrual cycle?
Oestrogen, FSH, LH
What is the role of FSH?
Causes an egg to mature, stimulates the release of oestrogen
What is the role of oestrogen?
Repairs & thickens the uterus lining, inhibits the release of FSH, stimulates the release of LH
What is the role of LH?
Causes a mature egg to be released.
List three non-hormonal methods of contraception, and state how they work.
- Condom - prevents sperm from reaching the egg
- Spermicial jelly - kills sperm before it reaches the egg
- Intrauterine device - prevents a fertilised egg from implanting on the uterus wall
How do hormonal methods of birth control reduce the risk of pregnancy?
They contain oestrogen, which inhibits the release of FSH, so no egg matures.
Outline the process of a nervous system response.
Stimulus –> receptor –> coordinator –> effector –> receptor
Outline the process of a reflex action.
Stimulus –> receptor –> sensory neuron –> relay neuron –> motor neuron –> effector –> response
What is a synapse?
A small gap between two neurons.
How do messages travel across a synpase?
When the electrical impluse reaches the end of a neuron, it stimulates the neuron to release a chemical messenger. The chemical messenger travels across the synapse and attaches to receptors on the second neuron. This stimulates the neuron to generate another electrical impluse.
What are the sense organs and what stimuli do they detect?
Skin - touch, temperature, pain Tongue - chemicals in food and drink Nose - chemicals in the air Eye - light Ear - sound
List some effectors and the response they could cause.
A muscle contracting to move an arm
A gland releasing a hormone into the blood
HT What hormone is released when blood sugar is too low?
Glucagon
HT Where is glucagon released from in the body?
The pancreas
HT What effect does glucagon have on blood glucose levels?
It causes glycogen from the liver and muscles to be converted back into glucose to be released into the blood, to increase blood glucose levels.
HT What hormones are given to a woman to increase the chance of becoming pregnant?
FSH and LH
HT What is infertility?
Not being able to get pregnant through sexual intercourse.
HT How can infertility be treated?
Fertility drugs to promote ovulation or through IVF
HT What are the steps in IVF?
- The woman is given fertility drugs to promote ovulation
- Eggs are collected and fertilised with a sperm sample in a lab
- The fertilised eggs develop into embryos
- The embryos are implanted into the mother’s uterus
HT What are some possible negative effects of IVF?
It can be emotionally and physically stressful, it does not have high success rates, it can lead to multiple births which can be a risk to the babies and mother
HT What is the role of thyroxine in the body?
It stiumulates the basal metabolic rate, and plays an important role in growth and development.
HT What is the role of adrenaline in the body?
Is increases heart rate and boosts oxygen and glucose delivery to the brain and muscles in times of fear or stress - it prepares the body for fight or flight.
