B10 - The Nervous System Flashcards
Why do we have senses?
So we can respond to our environment and benefit our survival.
Why does responding to our environment benefit our survival?
Prevents damage to our bodies.
Avoid predators.
Find food.
Seek shelter.
Find mates to reproduce.
What does homeostasis mean?
Regulations of internal conditions.
In response to internal and external changes.
To maintain optimal conditions for enzyme action and all cell functions.
What are three examples of regulations of internal conditions?
Body temperature.
Water content of the blood.
Blood glucose concentration.
What are 4 examples of in response to internal and external changes?
Water consumption.
Physical activity.
Carbohydrates in diet.
External temperature.
What are 3 examples of maintaining optimal conditions for enzyme action and all cell functions?
Enzymes denaturing if they get too hot.
Osmosis of water out of cells causing them to shrivel and not function.
Osmosis of water into cells so they burst and no longer function.
What is the order of the nervous system?
Stimulus - receptor - coordinator - effector - response
What is a stimulus?
An environmental change
What is a receptor?
Cells, tissues or organs that detect changes in the environment.
What is a coordinator?
Central nervous system that coordinates which effector to activate.
What is the effector?
Muscles or glands which caused responses.
What is a response?
A behaviour caused by effectors in reaction to the stimulus.
What are neurones?
Specialised cells which carry electrical impulses from receptors to effectors.
What is a sensory neurone?
Send electrical impulses from receptors to the coordination centres.
What is a relay neurone?
Sends electrical impulses to different parts of coordination centre.
What is a motor neurone?
Sends impulses from coordination centre to the effectors.
What is a conscious response?
a response to a stimulus which involved the conscious part of the brain.
Give examples if when conscious response is used?
controlling heart rate
blinking
closing eye’s iris
What is a synapse?
gaps between neurones where a transmitter substance is released.
What is a reflex response?
a fast, automatic response to a stimulus that bypasses the conscious part of the brain.
they protect the body from harm.
Billions of _____ neurones of the brain allow it to control ____ behaviours.
interconnected
complex
How can scientists study brain functions?
Functional MRI.
Standard MRI which can image the brain structures - must keep still.
Stimulate the brain with electricity and analyse which functions are activated.
Give 3 reasons why the brain is a difficult organ to study.
made from very delicate tissue.
found within a sealed skull structure.
brain is complex, controlling many functions.
What is the function of the cerebral cortex?
complex functions: memory, language, speech, consciousness.
What is the function of the cerebellum?
coordination, muscle movement and balance.
What is the function of the medulla?
unconscious/ reflex activities of the brain: heart rate, breathing.
What is the function of the Pituitary gland?
Gland that regulates fertility, water levels and controls other glands in the body.
What is the function of the Thermoregulatory centre?
Gland that regulates body temperature.
What are the functions of the brain?
body temperature
visual processing
triggers emotions
controls muscles
vocal speech
produces hormones
water levels
breathing rate
heart rate
language
balance
memory
What is narrowing the iris caused by?
The relaxation of radial muscles so they get longer.
The contraction of circular muscles, so they constrict.
What is widening the iris caused by?
The contracting of radial muscles so they get shorter.
The relaxation of circular muscles so they widen.
Iris narrows circular muscles are…
Contracted
Iris narrows radial muscles are..
Relaxed
Iris widens circular muscles are…
Relaxed
Iris widens radial muscles are…
Contracted
What is refraction?
when waves pass from one medium to another they change direction.
Thinner lenses refract strongly/slightly?
Slightly
Thicker lenses refract strongly/slightly?
strongly
If the lens is thicker, is the focal point further or closer to the lens?
closer to lens
If the lens is thinner, is the focal point further or closer to the lens?
further from the lens
What is lens accommodation?
changing the shape of the lens to focus onto the retina from near or distant objects.
Describe the lens accommodation for distant objects.
-light rays arrive nearly parallel.
-light rays need less refraction to focus on the retina.
-lens is pulled thin.
Describe the lens accommodation for near objects.
-light rays approach at a steeper angle.
-light rays needs more refraction to focus on the retina.
-lens is made thicker.
What are the 2 problems of the eye?
hyperopia (long-sighted) and myopia (short-sighted)
What happens when you have hyperopia?
Can’t thicken lens enough and there is too little refraction. Focal point is behind retina.
How can you fix hyperopia?
Additional biconvex lens causes more refraction to move focal point back to the retina. Lens can accommodate properly and so light focused on the retina.
Hard and soft contact lenses work like…
spectacle lenses
What can improper use of contact lenses lead to?
infection
What does lens replacement surgery do and what can it lead to?
replaces a faulty lens which can also lead to infection
What does laser eye surgery do?
changes the shape of the middle cornea with a laser, creating a lens effect.
