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Flashcards in Module 5 Deck (47):

What is homeostasis?

Conditions inside body need to keep steady, even when external environmental changes. Important because cells need right conditions in order to function properly including conditions for enzyme action. To sustain regulation in body to maintain a stable internal environment in response to changes in external and internal conditions.


How does th ebody perform homeostasis?

You have loads of automatic control systems in body to regulate internal environment, both nervous and hormonal communicatoin systems. All automatic control systems made up of 3 main components which work together a steady condition, cells called resceptors, coordination centres and effectors.


What is negetive feedback?

When levels of something gets too high or too low


What happens when a receptor detects a stimulus a level too high?

Coordination centre recieves and processes information then organises a response. Effector produces a response which conteracs change and restores optimum level, level deccreaes/increases if too low.


What happens in response to change in level in homeostasis?

Effectors will just cary on producing responses for as long as stimulated by coordinatoin centre. Might cause oppisate problem making level change too much. Luckily receptor detects if level becomes too different and negative feedback starts again.


Whst is the central nervous system?

In vertebrates this consists of brain and spinal cord. In mammals, CNS is connected ot body by sensory neurones and motor neurones. Recieves information from receptors and then coordinates a rsponse. Response carried out by effectors.


What is sensory neurons?

neurones that carry information as electrical impulses from receptors to CNS.


What is the motor neurones?

Neurones that carry electrical impulses from CNS to effectords.


What are the effectors?

All muscles and glands which respond to nervous impulses.


What are receptors and effectros ?

Receptors are cells that detect stimuli. Are many different types of receptors, such as taste receptors on toungue and sound receptors in ears. Receptors can form part of larger complex organs. Effectors respond to nervous impulses and bring about a change. Muscles and glands are known as effectors-they respond in different ways. Muscles contract in response to a nervous impulse, whereas glands secrete hormones.


What are synapses?

The connection between 2 neurons is called a synapse. Nerve signal is transferred by chemicals which diffuse across the gap. Theses chemicals then set off a new electrical signal in next neurone.


What are reflexes?

Reflexes are rapid, automatic responses to certain stimuli that doesn't involve the conscious part of brain-can reduce chances of being injured.


What happens if someone shines a bright light in your eyes?

Pupils automatically get small er so less light gets into eye-stops it getting damaged. If get a shock, body releases hormone aderaline automatically. Passage of infomation in a reflex is called a reflex arc.


What is the passage of the reflex arc and the CNS?

Neurons in reflex arcs go through spinal cord or through and unconscious part of brain. When stimulus is detected by receptors, impulses are sent along sensory neurone to relay neurone in CNS. When impulses reach a synapse between sensory neurone and relay neurone, trigger chemicals to be released. Chemiclas cause impulses to be sent along relay neurone. When impulses reach synapse between realy neurone and motor neurone, same thing happens. chemicals are released and cause impulses to be sent along motor neurone. Impulses then travel along motor neurone to effector. Muscles then contracts and move hand away from bee . Muscle contracts and moves hand away from bee.


Where is the brain, and what is it made up of?

Along spinal cord, brain is part of centrel nervous system. Made of billions of interconnected neurones. Brain is in charge of all complex behaviours. Controls and coordinated everything you do.


What is the cerebral cortex/

This is outer wrinkly bit. Responsible for things e.g. consciousness, intelligence, memory and language.


What is the medulla?

Controls unconcious activitiese.g. breathing.


What is the cerebellum?

responsible for muscle coordination.


How do you study students with brain damage?

If small part damaged, effect had on patient can tell you a lot.


How do you electrically stimulate the brain?

Brain can be stimulated electrically by pushing tiny electrode into tissue and giving small zap f electricity. By observing what stimulating different parts of brain does, possible to get idea of what those parts do.


What is an MRI scan/

Magnetic resonance imaging scanner is tube-like nachine that can produce detailed picture of brin structure. Scientists use to find out what areas of brain aer active on people when are doing things.


What are the negitives with studing the brain?

Studies have led to development of treatments for disorders of nervous system. Brain is complex and delicate-investigation of brain function and any treatment of brain damage or disease is difficult. Also carries risks: physical damage to brain.


What are the properties of the eye?

Sclera is tough, supporting wall of eye. Cornea is transparent outer layer found at front of eye. It reflects light onto eye. Iris contains muscles that allow it to control diameter of pupil and therefore how much light entres eye. Lens focuses light onto retina. Shape of lens is controlled by ciliary muscles and suspensory ligaments. Optic nerve carries impulses from receptors on retina on brain.


What is the job of the iris?

Bright light can damage retina-have to protect it. When light receptors in eye detect very bright light, a reflex is triggered that makes pupil smaller. Circular muscles in contract and radial muscles relax. Reduces amount of light can enter eye. Oppisite process happens in dim light. Radial muscles contract and circular muscles relax, makes pupil wider.


What happesn when you look at a near object?

Ciliary muscles contract, slackens suspensory ligaments. Lens becomes fat, increases amount by which it refracts light.


What happesn when you look at a far object?

Ciliary muscles relax, allows suspensory ligaments to pull light. Makes lens go thin. So refracts light by smaller amount. If lens can't refract light by right amount, person will be short or long-sighted.


What happens with people who are long-sighted?

Unable to focus on near objects. Occurs when lens is wrong shape and doesn't refract light enough or eyeball is too short. Image of near objects are brought into focus behind retina. Use glasses with convex lens to correct it. Lens refracts light rays so focus on retina. Hyperopia is medical term for long sightedness.


What happens with people who are short sighted?

Unable to focus on far objects. Occurs when lens is wrong shape and refracts light too much or eyeball is too long. Images of distant objects are brought into focus in fornt of retina. Can use glasses with concave lens to correct it, so that lightrays focus on retina. Myopia is medical term for short sightedness


What are contact lens?

Thin lenses that sit on surface of eye and are shaped to compenssate for faultin focusing. Popular because lightweight and almost invisible. More conveient than glasses for activities e.g. sport. 2 main types of contact lenses are hard lenses and soft lenses. Soft lenses are generally more comfortable, but carry higher risk of eye infections than hard lenses.


What is laser eye surgery?

Bad eyesight can sometimes be corrected with laser eye surgery. Laser can be used to vaporise tissue, changing shape of cornea. Simming it down makes it less powerful and can improve short sight. Changing shape so it's more powerful will improve long sight. Surgen can precisely control how much tissue laser takes off, completely correcting vision. However, is a risk of complications e.g. infections or eye reacting in way that makes vision worse than before.


What is replacement lens surgery?

Sometimes long-sightedness may be more effectively treatedby replacing lens of eye. In replacament lens surgery, natural lens of eye is removed and artificial lens, made of clear plastic, is inserted in its place. As involves work inside eye, replacing lens carries higher risks than laser eye surgery, including possible damage to retina.


How does the body keepe at the same temperature?

The thermoregulatory centre in brain contains receptors that are sensitive to temperature of blood flowing through brain. Thermoregulatory centre also recieves impulses from temperature receptors in skin, giving information about skin temperature.


What happens to cool the body down?

Temperature receptors detect core body temperature is too high. Thermoregulatory centre acts as coordination centre it recieves information from temperature receptors and triggers and effectors automatically. Effectors produce a response and counteract the change. Same if too high bidy temperature.


How do some effectors work antagonistically?

1 effector heat and another cols, work at same time to achieve a very precise temperature. Mechanism allows a more sensitive response.


What arethe body's processes to heat the body?

Sweat is produced by sweat gland and evaporates from skin. Transfers energy to environment. Blood vessels suppling skin dilate so more blood flows close to surface of skin. Called vasodilation. Helps transfer energy from skin to environment.


What are the body's processes to cool the body?

Hairs stand up to trap an insulating layer. Ne sweat produced. Blood vessels supplying skin capillaries constrict to close off skin's blood supply. Called vasoconstriction. When cold, shiver too. Needs respiration which transfers some energy to warm the body.


What is reaction time?

Time it takes to respond to a stimulus-often less than a second. Can be affected by factors e.g. age gender or drugs.


How does caffeine affect a person's reaction time?

Is drug-speeds up person's reaction time.


How should a person being tested present theirselves in a reaction time test?

Sit with arm resting on edge of a table.


How should the ruler be held in a reaction time test?

Hold vertically between their thumb and forefinger. Make sure 0 end of ruler is level with thumb and finger. Then let go without giving any warning.


When should the person catcha the ruler in a reaction time test?

As quickly as can.


How is reaction time measured in a reaction time test?

On ruler where it's caught. Number should be read from top of thumb. Further down ruler is caught, slower their reaction time.


Why should the experiment be repeated in a reaction time test?

To calculate mean distance ruler fell.


What should happen after the 1st mean is calculated in a reaction time test?

Person should have caffeinated drink. Then repeat experiment after 10 minutes.


Why do you need to control any variables in a reaction time experiment?

Make sure is fair test. E.g. should use same person to catch ruler each time, and person should always use same hand to catch ruler. Ruler should always be dropped from same height, should make sure person being tested hasn't had any caffeine before start of experiment.


What can too much caffeine cause?

Unpleasant side-effects, so person being tested should avoid drinking any more caffeine for rest of day after experiment is completed.


How can simple computer tests be used to measure reaction time?

E.g. person being tested has to click mouse as soon as see stimulus on screen. Computers give more precise reaction time because remove possibility of human error from measurement. As computer can record reaction time in milliseconds,can also give more accurate measurement. Using computer can also remove possibility that person can predict when to respond-using ruler tests, catcher may learn to anticipate drop by reading tester's body language.