Topic 5a The nervous system Flashcards
Define Homeostasis
Homeostasis is the regulation of conditions inside the body and cells to maintain a stable internal environment, in response to changes both internal and external conditions
Give two example conditions in your internal environment that need regulating and maintaining
Blood glucose content Body temperature Body water content
What is a stimulus
A change in your environment which may require a response
Name the part of the automatic control system that receives information about a stimulus and organises a response
Co-ordination centre
The water content in the body is monitored by a control system. If it gets to low, a negative feedback mechanism is triggered. Briefly outline the stages in this feedback system
- Receptors of detect a stimulus when the water content of the body is to low -This information is sent to the co-ordination centre, which organises an appropriate response from the effectors - The effectors respond to counteract the change bringing its level back to the optimum level. Receptor detect stimulus - co-ordination centre organises response - effector bring water level to optimum
What categories are the control systems which regulate your internal environment categorised into
Nervous and Hormonal (chemical communication systems)
What type of effector secretes hormones
Glands secrete hormones
A sensory neurone is a type of neurone. Name two other types of neurone
Relay found in CNS Relay neurone = Carry electrical impulses from the sensory neurones to the motor neurones and are found in the Central Nervous System Motor neurone = The neurones that carry the electrical impulses from the CNS to the effectors
A dog hears a cat moving in the garden and runs toward it. - What is the stimulus in this situation. - What detects the stimulus in this situation - What type of neurone transmits the information about the stimulus to the CNS
Stimulus - That sound of the cat moving Receptors in the dogs ears detect the stimulus (receptors sensitive to sound) Sensory neurone transmits the information to the CNS
What type of neurone transmits information from the CNS to an effector
Motor Neurone
How do nerve impulses travel between two neurones
The nerve signal is transferred by chemicals which diffuse across the synapse which sets off an electrical impulse in the next nuerone
What is a reflex
Reflexes are fast automatic responses to specific stimuli
Give an example of the bodies natural automatic reflex response
Bright light shinning in the eye. Your pupils automatically get smaller to prevent excessive amounts of light getting into your eye and damaging your sight.
Do reflex arcs travel through conscious parts of your brain
No - they are automatic responses which bypass your conscious part of the brain completely when a fast response is required
What trick can be used to remember the reflex arc
SRSRMER Stimulus - Receptor -Sensory N - Relay N - Motor N -Effector - Response
David steps on a drawing pin and immediately pulls his foot up What is the stimulus in this response? What is the effector in this response, How does it respond?
Stimulus = would be the pain felt from stepping on the pin The effector in this response would be the muscles contracting in order for David to lift his foot off the ground (moving foot away from the source of pain)
What is reaction time
The time taken to respond to a stimulus
Name the region of the brain that is important for consciousness
Cerebral Cortex - outer wrinkly layer of the brain responsible for consciousness, intelligence, memory and language Cerbral cortex = memory, intelligence, conciousness
Where in the brain is the cerebellum located
At the back of the brain behind the medulla and spinal cord on diagram. It is responsible for muscle co-ordination.
Where is the Medulla located
The medulla is at the base of the brain, at the top of the spinal cord. It controls unconscious activity (thing that you don’t have to think about) like breathing and your heart beat.
Ataxia is brain condition which can cause difficulty with walking. What part of the brain may be affected with ataxia.
The cerebellum as this is the part of the brain responsible for muscle co-ordination
What ways can neuro-scientists associate different parts of the brain with specific functions
- Studying patients with brain damage e.g. If a patient has a stroke damaging the back of the brain and the patient loses their vision we can identify that the back of the brain has something to do with vision
- Electrically stimulating the brain using electrodes to send electrical impulses to different parts of the brain and observing response
- MRI Scans Magnetic Resonance Imaging scanner to monitor brain activity
What type of organ is the eye
The eye is a sense organ
Name the different parts of the eye and their function
Sclera - Tough supporting wall of the eye
Cornea - Transparent outer layer found at the front of the eye. It refracts (bends)light into the eye
Pupil - The hole at the centre of the eye through which light enters Iris - Contains muscles which allow it to control the diameter of the pupil and therefore control how much light enters
Retina - Layer at the back of the eye which contains 2 light receptor cells one for light intensity and the other which is sensitive to colour
Lens - focuses the light into the Retina Cillary muscles and Suspensory ligaments control the shape of the lens
Optic nerve - carries impulses from the receptors on the retina to the brain
Describe how the eye responds to bright light
A reflex is triggered making the pupil smaller. The circular muscles in the iris and the radial muscles relax thus reducing the amount of light that can enter the eye.
Describe how the iris reflex protects the eye
Bright light can damage the retina. The iris reflex to bright light quickly reduces the amount of light which is able to enter the eye and in turn protects the retina from damage.
In relation to the eye what is accommodation
The process of the eye focusing light on the retina by changing the shape of the lens
What does a diagram of an eye looking at a distant object look like
The lens cillary muscles relax not touching the lens and the lens looks thinner
What happens when the eye wants to focus on an object nearby
- Cillary muscles contract which slacken the suspensory ligament - The lens becomes fat and more curved - This increases the amount by which it refracts light into the eye
What happens when the eye wants to focus on an object in the distance
- The cillary muscles relax which allows the suspensory ligaments to tighten - This makes the lens go thin (less curved) - So it refracts light by a smaller amount
What causes a person to be long or short sighted
When the lens cannot focus the light in the correct place on the retina
What is long sightedness
Long sightedness refers to people who are unable to focus on a near object - In long sighted people images are brought into focus behind the retina
What is the medical term for long sightedness
Long sightedness = Hyperopia Can be corrected by convex lens (curves outwards which refracts the light rays so they can focus on the retina)
What is the medical term for short sightedness
Short sightedness = Myopia Can be corrected by concave lens (curves inwards which refracts the light so the light rays can focus on the retina)
What is short sightedness
Short sightedness refers to people who are unable to focus on distant objects. This occurs when the lens is the wrong shape or the eyeball is too long
what is a contact lens
a thin lens that sight on the surface of the eye and are shaped to compensate for the fault in focusing
Name some alternative treatments for myopia and hyperopia other than glasses
Laser eye surgery - laser used to vaporise the tissue thus changing the shape of the cornea which effects how strongly it refracts light into the eye Contact lenses - Thin lens sits on surface of the eye and is shaped to compensate for the fault in focusing Replacement lens surgery - natural lens is removed and replaced with a plastic artificial one.
What is the thermoregulatory centre
Is a part of the brain which controls your bodies core internal temperature. Ideal temp 37c
Where does the thermoregulatory centre receive inputs about body temperature?
Information is received from receptors in the skin (cells which react to stimuli) sensitive to the temperature blood flowing through the brain as well as receptors in the skin sensitive to skin temperature which send information to the brain via nerve impulse
In what way does the body respond to an increase in core body temperature
- Hairs on the skin lie flat reducing the air trapped near the surface of the skin. This allows heat to be transferred from the skin to the environment more easily - Sweat is produced by sweat glands, When sweat evaporates from the skin, it transfers energy to environment helping to reduce body temperature. - Blood vessels supplying the skin capillaries dilate (get wider). This allows more blood to flow close to the surface of the skin. This is called VASODIALATION. It helps transfer energy to the environment.
In what way does the body respond to a drop in core body temperature
- Hairs stand up on the skin trapping the air near the surface of the skin and creating an insulating barrier to reduce the amount of energy transferred to the environment - No Sweat is produced - blood vessels supplying skin capillaries constrict to reduce the skins blood supply (VASOCONSTRICTION). It reduces the amount of blood that flows close to the surface of the skin and so less energy is transferred from the skin to the environment
What is the order of response to a stimulus
Receptor is stimulated - signal sent along neurones to the brain - brain co-ordinates a response - signal sent along neurones to the effector
What are neurones
Neurones are individual nerve cells which are bundled into nerves
