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| Question | Answer |
|---|---|
| What is meant by the internal environment of the body? | the conditions inside the body like pH and temperature |
| What is homeostasis? | the regulation of the internal conditions of an organism to maintain optimum conditions for function in response to internal and external changes |
| How do humans survive in conditions from the cold Arctic to the hot Saharan desert? | homeostasis keeps conditions inside the body steady so organs and enzymes can function properly despite external conditions |
| What controls the functions of the cell? | enzymes control all the functions of the cell |
| Why is homeostasis important to enzymes? | enzymes work best in specific conditions which homeostasis maintains |
| Why is homeostasis important for cell functions? | cell functions require specific conditions to operate and homeostasis maintains these specific conditions |
| Name the internal conditions controlled in the human body. |
• body temperature • the water content of the body • blood glucose concentration |
| What is responsible for detecting and responding to changes in the body? | automatic contol systems |
| Name the key components of an automatic control system. |
• receptors • coordination centres • effectors |
| Give examples of things included in automatic control systems? | they include nervous responses in the nervous system, chemical responses in the hormone system, and the organs of the body |
| What might happen to the organs if the internal environment kept changing? | the organs may • function poorly • stop functioning • be damaged permanently, or • fail completely |
| What are receptors? | cells that detect changes in the internal and external environment |
| What are changes in the internal and external environment called? | stimuli |
| What do coordination centres do? |
• they receive information from the receptors • they process information from the receptors • they send out signals to coordinate the response of the body |
| Name a coordination centre. | the brain |
| What does the brain coordinate? |
• the nervous system • parts of the hormonal system • the spinal cord • the pancreas |
| What are effectors? | muscles or glands that bring about changes to received stimuli |
| What is achieved by the actions of effectors? | they restore conditions in the body to the optimum levels |
| Question | Answer |
|---|---|
| What does the nervous system enable an organism to do? | it enables an organism to monitor the surroundings then respond and cooridinate the response |
| What is carried by the nervous system? | electrical impulses |
| What is the speed of electrical impulses in the nervous system? | between 1 and 120 metres per second |
| How are changes in the surroundings detected by a person? | using cells called receptors |
| What are changes in the surroundings called? | stimuli (one stimulus) |
| Describe receptor cells. |
• there are many different types of receptor cells • they are similar to most animal cells • they have a nucleus, cytoplam and a cell membrane • they are usually found clustered together in special sense organs |
| List five special sense organs that contain sensory receptors. |
• ears • eyes • skin • nose • tongue |
| Give an example of sense organs operating in an animal. | male moths to detect the scent of a female, sometimes many kilometres away |
| Describe the sense organ sensitive to sound. | ears |
| What receptors are in the eyes? | receptors sensitive to light |
| What external stimuli do the ears respond to? |
• sound for hearing • changes in position for balance |
| Which receptors assist with balance? | sensory receptors in the ears monitor change in position for balance |
| What are the sense roles of the nose and the tonguer? | they contain receptors sensitive to chemicals for taste and smell |
| What happens when a sensory receptor detects a stimulus? |
• the sensory receptor initiates an impulse (electrical signal) • the impulse travels along sensory neurones until it reaches the central nervous system (CNS) • the CNS processes the information and coordinates the response • the CNS sends an impulse along motor neurones to the effectors • the effectors respond as required by the CNS |
| Draw a graph to show the path of an impulse from stimulus to the completed action. | stimulus → receptor → sensory neurone → CNS → motor neurone → effector |
| What is a nerve? | a bundle of hundreds or thousands of neurones |
| What is the CNS | the CNS is made up of the brain and the spinal cord |
| What are effectors | they respond to impulses sent from the CNS and can be muscles or glands |
| How do muscles respond to a stimulus? | they contract |
| How do glands respond to a stimulus? | they secrete chemicals |
| List two glands with a stimulus and their response. |
• the salivary glands produce and release saliva in response to the smell of food cooking • the pancreas releases the hormone insulin when blood sugar levels rise after a meal |
| Label a sensory neurone. | 
|
| Label a motor neurone. | 
|
| Question | Answer |
|---|---|
| What is a quick, automatic response called? | a reflex |
| List 3 examples of reflex actions. |
• pulling back when touching something hot • blinking when something comes near your face • jumping when you get a fright |
| What is the purpose of quick reflex actions? | they help to avoid danger and harm by happening quickly and without conscious thought |
| What are the two purposes of reflex actions? |
• quick reactions to avoid danger and harm • taking care of basic body functions |
| Name two basic body functions that are reflex actions. |
• breathing • moving food through the intestines |
| List the charateristics of reflex actions. |
• automatic • rapid • without conscious thought |
| Name the neurones involved in a reflex action. |
• sensory neurone • relay neurone • motor neurone |
| What is a relay neurone? | they are found in the CNS and connect sensory neurones to motor neurones |
| Describe the pathway that the electrical impulse follows in a relay action. |
• the impulse from the receptor down the sensory neurone • it then passes along the relay neurone usually in the spinal cord • finally it travel through the motor neurone to the effector organ |
| What is the pathway called that the impulse follows in a reflex action? | a reflex arc |
| Why does the impulse in a reflex response bypass the conscious brain? | to make the time between the stimulus and the reflex response as short as possible |
| What is found between the 3 types of neurones in the reflex arc? | there is a physical gap called a synapse - the neurones do not touch |
| What mechanism is used by an impulse to travel across the synapse to reach the next neurone? | chemicals are used cross the synapse |
| Describe the chemical process used by an impulse to travel across the synapse. |
• the impulse arrives at the junction of the neurones • chemicals are released by the neurone • chemicals cross the synapse • the chemicals arrive at receptor sites • a new impulse is generated |
| How does the speed of the electrical impulse compare with the speed of the chemical diffusion in the synapse? | the electrical impulse is much faster than chemical diffusion across the synapse |
| Describe in detail what happens when you touch a hot object. |
• a receptor is stimulated when a hot object is touched • an impulse is generated by the receptor • the impulse travels down the sensory neurone • the impulse in the sensory neurone arrives at the synapse • a chemical is released • the chemical diffuses across the synpase • the chemical reaches the relay neurone where it generates a new impulse • the impulse travels along the relay neurone • the impulse reaches the synapse between the relay and motor neurone • a chemical is released into the synapse, diffuses across it, and generates a new impulse in the motor neurone • the impulse travels down the motor neurone • the impluse reaches the effectors in the arm muscle • the muscle contracts • the hand is moved away from the hot object |
| What is the difference between the pathway in a reflex action and a conscious action? | in a reflex action, the cooridnator is a relay neurone in the spinal cord or the uncounscious area of the brain |
| When do you become aware of a reflex action? |
• at the same time that the impulse is sent down the motor neurone, and impulse is also sent to the conscious brain • the person thus becomes aware of the reflex action but only after it has happened |
| Question | Answer |
|---|---|
| Where does information collected by the sensory receptors finish? | it all ends up in the brain |
| What does the brain do with the information it receives? | it processes the information and then sends out the impulses to co-ordinate a response to the specific situation |
| What does the brain control? | everything from walking to thoughts and feelings |
| How is the brain protected? |
• by the bones of the skull • it is encased in protective membranes called the meninges |
| What is the texture of the brain? | it can be described as being like set yoghurt |
| What is the brain made uo of? | billions of interconnected neurones organised into regions |
| What is the purpose of the different regions? | each region performs specific functions |
| Name five key regions in the brain. |
• the cerebral cortex • cerebellum • the medulla • hypothalamus • pituitary gland |
| What is the function of the cerebral cortex? | it is concerned with consciousness, intelligence, memory, and language |
| What is the function of the cerebellum? | it is concerned with coordinating muscular activity and balance |
| What is the function of the medulla? | it is concerned with unconscious activities such as controlling the heartbeat, the movements of the gut, and breathing |
| What is the function of the hypothalamus? | it is involved in controlling body temperature |
| What is the function of the pituitary gland? | it is plays a big part in controlling and coordinating body systems |
| What provided early evidence for the roles of different areas of the brain? | people suffereing brain damage; by matching changes in behaviour or memory with the damaged area has enabled scientists to map the functions of some parts of the brain |
| What important brain damage incident helped scientists understand the brain in 1848? | an explosives accident blew an iron rod through the skull of 25-year-old Phineas Gage |
| How did the rod through his brain affect Phineas Gage? | before the accident he was polite and hardworking and afterwards he became wild, rude, and unreliable | `
| What is it believed caused the change in Phineas Gage's personality? | modern scans show that the accident removed part of his cerebral cortex, including the area that controls social inhibitions |
| Name four techniques enable scientists to study the brain. |
• studying people with brain damage • electrically stimulating different parts of the brain • MRI scans • problems with the brain |
| How do scientists gain access to the brain to stimulate it for research? | by removing the top of the skull |
| What effect of stimulating different areas of the brain? | people can experience hunger, thirst, anger or fear just by stimulating the relevant area of the brain |
| Why is surgery usually done on conscious patients? | there are no sensory nerve endings in the brain |
| What does MRI stand for? | magnetic resonance imaging |
| What do MRI scans allow scientists to do when studying the brain? | they can take pictures of brain activity on live patients |
| Make two medical conditions of the brain affect behaviour? | a stroke or a tumour |
| Why are MRI scans of patients with a brain tumour or after a stroke useful to scientists studying the brain? | they show which areas of the brain have been affected allowing scientists to link parts of the brain to changed function and behaviour |
| How else are MRI scanners used to understand the brain? | MRI scanners can take pictures of brain activity while a person performs a task |
| What are the challenges with studying and treating the brain? |
• it is very complex with billions of neurones • it is very delicate so easily damaged • many processes involve large numbers of neurones in many different areas • there are a range of chemicals like hormones that affect the behaviour of the neurones in the brain |
| Question | Answer |
|---|---|
| What is the eye? | it is a sense organ containing receptors in the retina that are sensitive to light intensity and colour |
| Where are the light sensitive cells? | at the back of the eye in a light-sensitive layer known as the retina |
| What is the sclera? | the white outer layer of the eye |
| What is the main property of the sclera? | it is tough and strong so the eyeball is not easy to damage |
| What is the cornea? | it is a transparent area in the sclera at the front of the eyeball |
| What is the function of the cornea? |
• it lets light into the eye • it bends the direction of the light to focus them on the retina |
| What does the iris do? | it is made of muscles that contract and relax to regulate the amount of light reaching the retina through the pupil |
| What happens to the iris in bright light? | the circular muscles contract and the radial muscles relax in the iris so the pupil constricts and reduces the amount of light entering the eye |
| Why does the pupil become small in bright light? | to reduce the amount of light entering the eye because too much light can damage the delicate, light-sensitive cells |
| What happens to the iris in dim light? | the circular muscles relax and the radial muscles constrict in the iris so the pupil dilates and increases the amount of light entering the eye |
| What does light pass through after the pupil? | a clear disc called the lens |
| How is the lens held in place? | by suspensory ligaments and the ciliary muscles |
| What is the role of the lens? | it focuses the light on the retina to produce a clear image |
| What fills the eyeball? | a clear transparent jelly that maintains its spherical shape |
| What happens when light hits the retina? | the light sensitive cells are stimulated sending impulses to the brain along sensory neurones in the optic nerve |
| What is the blind spot? | the point where the optic nerve leaves the eye |
| Why does the blind spot not create a hole in what people see? | the brain fills in the space completing the picture |
| What is the function of the optic nerve? | it carries impulses from the retina to the brain |
| Why does light entering the eye need to be focused? | to be able to see clearly |
| What happens if the light is not focused on the retina? | the image will be blurred if the light is focused in front of or behind the retina |
| What is the process called that focuses light in the eye? | refraction |
| What is refraction? | it refers to changing the direction of light |
| What parts of the eye refract the light that enters? | the cornea, the lens and the jelly of the eyeball |
| How does the eye focus light? | the shape of the lens of the eye can change shape by the contraction and relaxation of the ciliary muscles |
| What is the effect of changing the shape of the lens of the eye? | it changes the amount the eye refracts light |
| How does the image appear on the retina? | it is upside down |
| Why do we not see images upside down when the image on the retina is upside down? | the brain turns the image upright |
| Question | Answer |
|---|---|
| What is accommodation in the eye? | the process of changing the shape of the lens of the eye to focus on near or far or distant objects |
| Describe the light that reaches the eyes from close objects? | the light is spreading out or diverging very strongly |
| Describe the light that reaches the eyes from distant objects? | the light is travelling in almost parallel rays |
| What does the cornea do? | it refracts (changes the direction) of the light entering the eyes towards the retina |
| What does the lens do? | the lens makes it possible to see close and distant objects equally well by changing shape to focus light on the retina |
| How does the eye see distant objects? |
• the ciliary muscles relax • this pulls the suspensory ligaments tight • which pulls the lense thin and flat • only causing light to be slighted refracted • it focuses the light on the retina |
| How does the eye see near objects? |
• the ciliary muscles contract • this lets the suspensory ligaments loosen • so the lens thickens and more curved • causing light to be strongly refracted • it focuses the light on the retina |
| Why are older people more likely to need glasses> | the lens of the eye hardens making accommodation more difficult |
| Name two common eye defects. |
• myopia - short sightedness • hyperopia - long sightedness |
| What is the effect on sight of both myopia and hyperopia? | the rays of light are not focused on the retina so the image is blurred |
| What can and can't you see with myopia? | it is possible tp see close objects clearly while distant objects are blurred |
| Why are distant objects blurred with myopia? | light is focused in front of the retina so the images that reach the retina are out of focus |
| Name two possible causes of myopia. |
• a long eyeball • the lens is too curved |
| What is the most common way of treating myopia? | wearing glasses with a concace lens |
| How does wearing glasses with concave lenses help with myopia? | it spreads out light before it reaches the eye |
| What can and can't you see with hyperopia? | it is possible to see distant objects clearly while close objects are blurred |
| Why are near objects blurred with hyperopia? | the lens cannot bend the light strongly enough it is focused behind the retina so the images that land on the retina are out of focus |
| Name two possible causes of myopia. |
• a short eyeball • the lens is too flat and too thin |
| What is the most common way of treating hyperopia? | glasses with convex lenses |
| How does wearing glasses with convex lenses help with hyperopia? | the lenses bring the light rays closer together before they reach the eye so the lens can bring the image into perfect focus |
| Name three new methods of overcoming myopia and hyperopia. |
• contact lenses • laser eye surgery • replacement lenses |
| Where are contact lenses placed? | on the surface of the eye |
| What do they do different to glasses? | they work the same way as conventional glasses |
| What is the advantage of contact lenses? | they cannot be seen and make activities like doing sport much easier |
| Describe hard contact lenses? |
• they are made of a hard material • they are rigid • they last a long time • they have to be removed overnight • they have to kept sterile to avoid eye infections |
| What are the most modern contact lenses like? | they are soft |
| What are the advantages of soft contact lenses? | they are made of more flexible material making them more comfortable to wear |
| What are the disadvantages of soft contact lenses? | they do not last as long |
| Describe the different types of soft contact lenses |
• some soft lenses can be worn every day for a month - they must be soaked in sterile solution overnight • some soft lenses are disposable - worn for a day and thrown away |
| When can a person have laser eye surgery? | it is only available to adults once their eyes have stopped growing and their vision has become stable |
| How are lasers used to treat myopia? |
• to reduce the thickness of the cornea so it reflects the light less stronglybr>
• so distant light is focused on the lens and instead of in front of tbe lens |
| How are kasers used to treat hyperopia? | to change the curve of the cornea so it refracts light from close objects more effectively |
| What is done when replacment lenses are used to treat myopia or hyperopia? | another lens is added inside the eye to correct the visual defect permanently |
| Describe the two main techniques that are used with replacement lenses. |
• the permanent contact lens is implanted into the eye and the natural lens is left in place • the faulty lens is replaced by an artificial lens |
| What are the risks of lens replacement? |
• damage to the retina • cataracts developing if the natural lens is left in place • infections |
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