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41 Cards in this Set
- Front
- Back
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What is a stimulus? |
A change in your environment which you may need to react to. They are detected by sense organs. |
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What are receptors? |
Your 5 different sense organs all contain different receptors. Receptors are groups of cells which are sensitive to stimulus. They turn stimulus energy (e.g light energy) into electrical impulses. |
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Give some examples of a stimulus. |
Light, sound, pressure, touch, chemical, or a change in position or temperature. |
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What are the 5 sense organs? |
Eyes ears skin nose tongue. |
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What receptors do these sense organs contain? Eyes, ears, nose, tongue, skin? |
Eyes- light receptors Ears- sound and balance receptors Nose- smell receptors (detect chemical stimuli) Tongue- taste receptors (detect chemical stimuli) Skin- sensitive to touch, pressure and temperature change |
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What are sensory neurones? |
The nerve cells that carry electrical impulses from the receptors in the sense organs to the CNS. |
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What are motor neurones? |
The nerve cells that carry the signals to the effector muscles or glands. |
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What are effectors and what do they do? |
Muscles - contract and relax Glands - secret hormones |
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What is in the CNS? |
The brain and the spinal cord. |
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What does the CNS do? |
Is where all the information from the sense organs is sent, and so it coordinates a response. |
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What is a reflex? |
An automatic response to certain stimuli, which reduces the chances of being injured. |
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What is a reflex arc? |
The passage of information in a reflex (from receptor to effector) |
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Describe what happens in a reflex arc? |
-Receptors detect stimuli, so an impulse is sent along a sensory neurone to the spinal cord. -In the spinal cord the message is passed to a relay neurone. -The relay neurone relays the impulse to a motor neurone. -The impulse then travels along the motor neurone to the effector. |
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What is a synapse and how does it work? |
The connection between two neurones. The nerve signal is transferred by chemicals which diffuse across the gap and set off a new electrical signal in the next neurone. |
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What are hormones? |
Hormones are chemical messengers which travel in the blood to activate target cells. -released directly into the bloodstream. -carried in the blood plasma. -control things in organs and cells that need constant adjustment. |
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Where are hormones produced? (Give four examples) |
Glands - Pituitary gland, pancreas, testes (male), ovaries (female). |
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How fast do hormones travel through the body? |
At the "speed of blood". |
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What hormones does the Pituitary gland produce? |
LH, FSH and ADH(which controls water content) |
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What hormone does the pancreas produce? |
Insulin to control blood sugar. |
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What do the ovaries do? |
Produce oestrogen which controls the Menstrual cycle and promotes a female secondary sexual characteristics. |
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What do the testes do? |
Produce testosterone which promotes all male secondary sexual characteristics. |
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What are 3 differences between hormones and nerves? |
Nerves: -very fast message -act for a very short time -act on a very precise area Hormones: -slower message -act for a long time -act in a more general way |
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What is the Menstrual cycle? |
The monthly release of an egg from a woman's ovaries, and the build up and breakdown of the protective lining in the womb. |
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What happens in the 4 stages of the Menstrual cycle? |
Stage 1: uterus lining breaks down for about 4 days. Stage 2: the lining of the womb builds up from day 4-14. Stage 3: an egg is developed and released from the ovary at day 14. Stage 4: the wall is maintained for about 14 days. |
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How does the hormone FSH (Follicle-Stimulating Hormone) control the Menstrual cycle and where is it produced? |
-produced by the Pituitary gland. -causes an egg to mature in one of the ovaries -stimulates the ovaries to produce oestrogen |
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How does the hormone oestrogen control in the Menstrual cycle and where is it produced? |
-produced in the ovaries -causes the Pituitary gland to produce LH -inhibits the release of FSH |
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How does the hormone LH (Luteinising Hormone) control the Menstrual cycle and where is it produced? |
-produced by the Pituitary gland -stimulates the release of an egg at around the middle of the Menstrual cycle |
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What hormone does the pill contain and how does it work? |
Oestrogen. Prevents the release of an egg and inhibits the production of FSH, which stops the development and production of eggs. |
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What are 2 advantages of the pill? |
Over 99% effective. Reduces the risk of getting some types of cancer. |
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What are 3 disadvantages of the pill? |
Isn't 100% effective. Can cause side effects - headaches, nausea. Doesn't protect against STDs. |
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How does the hormone FSH increase fertility? |
Stimulates egg production. |
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What is an advantage of FSH? |
Helps a lot of women get pregnant. |
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What are 2 disadvantages of FSH? |
Doesn't always work - can have to do it many times=expensive. Too many eggs could be stimulated resulting in multiple pregnancies (twins, triplets). |
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What is IVF? |
Eggs are collected from a woman's ovaries, fertilised in a lab, grown into embryos and then transferred back into the woman's womb. Hormones are also given before egg collection to stimulate egg production (more than 1 egg can be collected). Oestrogen and progesterone are often given to make embryo implantation more likely to succeed. |
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What are 2 problems with IVF? |
Some of the hormones used can: Cause abdominal pain, vomiting and dehydration. Increase risk of cancer. |
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What does homeostasis mean? |
It is all the functions in your body that try to maintain a constant internal environment. All your body's cells are bathed in tissue fluid, which is blood plasma which has leaked out of the capillaries and keeps your cells working properly. |
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What are the 4 things in homeostasis that need to be controlled? |
Ion content. Sugar content. Water content. Temperature. |
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How is ion content regulated? |
Ions are taken into the body in food. Some ions are lost in sweat. The kidneys will remove the excess from the blood, which is then got rid of in urine. |
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What are 3 ways water is lost from the body? |
Through the skin as sweat. Via the lungs in breath. Via the kidneys as urine. |
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How is body temperature controlled? |
Part of the brain is sensitive to the blood temperature in the brain and receives messages from the skin about skin temperature. Body needs to be kept at 37°C because then enzymes in the human body work best. |
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How are blood sugar levels controlled? |
Insulin makes sure there is enough glucose in the blood by adding and removing it. Diabetes Type 1 is where your body doesn't produce enough insulin. |
