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46 Cards in this Set
- Front
- Back
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What does the nervous system do?
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It lets you take in information about the world around you and respond right away.
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What are the three types of neurones involved with reflex actions?
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Sensory neurones.
Motor neurones. Relay neurones. |
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What are sensory neurones?
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They are nerve cells that carry signals as electrical impulse from the receptors in the sense organs to the central nervous system.
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What are motor neurones?
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The nerve cells that carry signals to the effector muscles or glands.
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What are relay neurones?
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They connect a sensory neurone and a motor neurone.
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What are receptors?
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They are groups of cells which are sensitive to stimulus. They change stimulus energy into electrical impulses.
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What is a stimulus?
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It is a change in your environment which you may need to react to. You need tobe constantly monitoring what's going on so you can respond if you need too.
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What do sense organs do?
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They detect stimuli.
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What are the 5 different sense organs?
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Eyes, ears, nose, tongue and skin.
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What can a stimulus be?
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Light, sound, touch, pressure, chemical, or a change in position or temperature.
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What is the CNS?
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The central nervous system, it is where all the information from the sense organis is sent, it is also where reflexes and actions are coordinated.
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What is the CNS consisted of?
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The brain and spinal cord only.
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Explain what happens in the CNS
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Neurones transmit the information (as electrical impulses) very quickly to the CNS. "Instructions" from the CNS are sent to the effectors (muscles and glands) which respond accordingly.
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What are effectors?
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Muscles and glands are known as effectors. They respond in different ways.
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How do muscles and glands respond in different ways?
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Muscles contract in response to a nervous impulse whilst glands secrete hormones.
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What are reflexes?
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They are automatic response to certain stimuli-they can reduce the chances of being injured.
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What is the route taken by the information in a reflex called?
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A reflex arc.
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Where does the reflex arc go through?
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The neurones in the reflex arc go through the CNS.
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What happens from the stimulus to the response?
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Stimulus-Receptor-Sensory Neurone-Relay Neurone-Motor Neurone-Effector-Receptor
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What do synapses do?
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They connect neurones. The connection between two neurones is called a synapse.
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What are neurones?
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Another word for nerve cells.
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Why are neurones long and have branched endings?
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They have a branched ending so that they can connect with lots of other neurones. They're long which speeds up the impulse, fewer connections means a quicker signal.
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How are nerve signals transferred?
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By chemicals which diffuse across the gap. These chemicals set off a new electrical signal in the next neurone.
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What are hormones?
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Hormones are chemical messengers which travel in the blood to activate target cells.
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What do hormones control?
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Organs and cells that need constant adjustment, hormones tend to have relatively long-lasting effects.
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What hormones does the pituitary gland produce?
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LH,FSH-these are all to do with fertility and ADH which controls water content.
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What hormone do ovaries produce?
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They produce oestrogen, which controls the menstrual cycle, and is involved with puberty.
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What hormone does the pancreas produce?
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Insulin, which controls blood sugar.
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What hormones do the testes produce?
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Testosterone which is involved with puberty.
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What are the differences between nerves and hormones?
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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 homeostasis?
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Homeostatsis is maintaining a constant internal environment.
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Why do conditions in your body need to be kept steady?
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So that cells can function properly, you need to balance inputs and outputs in your body.
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Name some examples of balancing inputs and outputs?
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Levels of CO2 (respiration constantly produces this and you need to get rid of it)
Levels of oxygen (you need to replace oxygen that your cells use up in respiration) Water content (you need to keep a balance between the input and output of this) Body temperature (you need to keep at a steady temperature) |
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What is negative feedback?
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Changes in the environment trigger a response that counteracts the changes. EG: a rise in body temperature causes a response that lowers body temperature. This means your body environment can attempt to stay normal,which is the level where your cells work back. If the environment changes to much, then it can be difficult to counteract it.
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How is water lost in the body?
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Through the skin as sweat, from the lungs when we breath and from the kidney when we urinate.
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How does the body cool you down when you're too hot?
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Hairs lie flat, lots of sweat is produced, blood vessels close.
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How does the body heat up when you're too cool?
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Hairs stand on end, little sweat is produced, blood vessels constrict, you shiver.
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What happens when your blood glucose level is too high?
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Insulin is added.
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What happens when your blood glucose level is too low?
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Insulin isn't added.
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How does glucose get into your blood?
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By eating foods containing carbs, normal respiration or exercise gets rid of it, the levels of glucose needs to be kept steady and are monitored by the pancreas.
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What is diabetes (type 1)
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It is when the pancreas doesn't produce enough insulin, if the level of blood glucose level is too high then it'll kill them.
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How can diabetics avoid getting blood glucose levels too high?
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By avoiding foods rich in carbohydrates or by injecting insulin. By injecting insulin, the liver removes the glucose as soon as it enters the blood so the level of glucose will remain steady.
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Why is it important to have glucose in the blood?
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Glucose is needed for cellular respiration. Respiration gives you energy so if you had no glucose, you'd have no energy.
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What happens if blood glucose levels are too high?
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Water will diffuse out of the cells,you'll become dehydrated and the cells will be unable to perform their normal functions.
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Why is it important that the blood glucose levels are too low?
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Cells will explode due to their being too much water,eventually leading to them respiring.
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What is the function of the kidney?
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It controls salt/water balance of the blood plasma, it also excretes urea.
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