Topic 5-Homeostasis And Responce Flashcards
What system is the brain part of?
The Central Nervous system.
Along with the spinal cord
Made up of billions of interconnected neurones
In charge of all complex behaviour
Controls and coordinates everything you do.
E.g Breathing, running and sleeping
What are the regions of the the brain?
The cerebral cortex
The medulla
The cerebellum
What is the Cerebral Cortex?
- the outer ‘wrinkled’ layer of the brain
- responsible for intelligence, language, memory and consciousness
What is the Medulla?
-lower part of the brain stem
(Base of brain, at the top of the spinal cord)
-responsible for involuntary coordination.
E.g breathing, swallowing
What is the Cerebellum?
- lower part of the back of the brain
- responsible for voluntary coordination of the muscles
What are the different methods to study how the brain works?
- studying patients with brain damage
- electrically stimulating the brain
-magnetic resonance imaging scans
(MRI scan)
Explain the method of studying patients with brain damage.
-if a small part of the brain has been damaged, the effect this has on the patient can tell you a lot about the damaged part of the brain does.
Explain the method of electrically stimulating the brain.
- Stimulated electrically by punching a tiny electrode into the tissue and giving it a small zap of electricity
- when stimulated it shows what different parts of the brain does
E.g certain parts of brain muscle contract and move when stimulated
Explain MRI scan.
-scientists use it to find out what areas of the brain are active when people are doing things like listening to music or trying to recall a memory.
What is the benefits and risk of studying the brain?
- electrical stimulation can reduce muscle tremors
- surgery to remove a part of the brain that’s causes seizures can treat epilepsy
-can cause physical damage or increased problems with brain function
(E.g Difficulties with speech)
What are the parts of the eye?
- sclera
- cornea
- pupil
- iris
- retina
- lens
- ciliary muscles and suspensory ligaments
- optic nerve
What is the sclera?
- tough, supporting wall of the eye
- protects and holds eye in place
What is the cornea?
- transparent outer layer found at front of eye
- refracts light into the eye
What is the pupil?
- hole in centre of the eye
- through which light enters
What is the iris?
- contains muscles that control the diameter of pupil
- regulates the amount of light reaching the retina
What is the retina?
- layer at the back of eye
- contains two types of light receptors
- one is sensitive to light intensity
- other is sensitive to colour
-contains rods and cone cells
What is the lens?
-focuses light into the retinas
What is the ciliary muscles and suspensory ligaments?
-control the shape of the lens to focus light rays on the retina
What is the optic nerve?
-carries impulses from the receptors on the retina to the brain
What is accommodation?
The process of changing the shape of the lens to focus on the near or distant objects
What happens when you try and focus on a distant object?
- Ciliary muscles relax
- Suspensory ligaments pull tight
- Makes Lens pull thin (less curved)
- So refracts light by a smaller amount
What happens when you focus on a near object?
- Ciliary muscles contact
- Suspensory ligaments loosen
- Makes lens go thicker (more curved)
- The amount of light refracted increases
What is long-sightedness called?
Hyperopia
What is short-sightedness called?
Myopia
Explain myopia.
- can’t focus on objects that are far away
- usually occurs when the eyeball is too long
- light rays from distant objects focus in the eyeball in front of the retina
- can be corrected by concave lenses (curved inwards) so that the light rays can focus on the retina
Explain Hyperopia
- can’t focus on objects that are near
- usually occurs when the eyeball is too short
- light rays from distant objects focus in the eyeball behind the retina
- can be corrected by convex lenses (curved outwards) so that the light rays can focus on the retina
What are alternate treatments for myopia and hyperopia?
- contact lenses
- laser eye surgery
- replacement lens surgery
Explain contact lens.
- thin lenses on surface of eye
- shaped to compensate for fault in focusing
- lightweight and almost invisible and more convenient for sports
- two types soft lenses and hard lenses
- soft are more comfortable but has higher risk of eye infections
Explain laser eye surgery.
-vaporises tissue, changing the shape of the cornea
(changing how strongly it refracts light into eye)
- slimming it down to make less powerful to improve short sight
- changing shape to make more powerful to improve long sight
- risk of complications such as infection or eye reacting in a way making vision worse
Explain lens surgery.
- good for long-sightedness
- natural lens is removed and artificial lens made of plastic is inserted in its place
-higher risk of laser eye surgery
-could damage retina
(which could lead to loss of sight)
