B10 The Human Nervous System Flashcards
What are the 2 main parts of the human nervous system?
The spinal chord and the CNS (central nervous system)
What does the CNS consist of?
- The brain
- Neurones
Which part of the brain is responsible for language, memory and consciousness?
The Cerebral cortex
Which part of the brain is responsible for the heart rate and breathing rate?
The Medulla
Which part of the brain is responsible for movement coordination and balance?
The Cerebellum
Why is it difficult to study the brain and treat brain damage?
- The brain’s protected by the skull, making it hard to
access - The structures of the brain are extremely complex -
it’s difficult to identify which part performs which
function - The brain is delicate and easy to damage
What are the 3 ways scientists use to investigate the brain?
- Study patients with brain damage - by identifying
where the damage has occurred, they can link it to its
function - Electrically stimulate the brain, and look at the effects
on the persons behaviour, narrowing down specific
regions to their functions - Use MRI scanning to see which parts of the brain are active while performing different activities
What type of organ is the eye?
A sense organ
Describe how the eye detects light
Light rays first travel through the transparent front of the eye - the Cornea, then through the pupil, then through the lens, which focuses the light rays onto the back of the eye - the Retina. The Retina contains receptor cells which detect light intensity and colour, and send electrical impulses down the Optic nerve
Where is the Cornea located and what is it’s function?
At the front of the eye, and it’s job is to begin focusing light rays
What is the pupil
The space in the centre of the iris which light passes through
What is the function of the lens?
To focus light rays onto the back of the eye
What is the purpose of the Sclera?
It protects the eye
What 3 components work together to enable accommodation?
- The ciliary muscles
- The suspensory ligaments
- The lens
What’s the job of the Iris?
To control the amount of light that enters the pupil
Describe what would happen to a person’s pupils if they went in a dark room?
The drop in light intensity is sensed by light receptors in the retina, which send electrical impulses to down the optic nerve to the brain, which sends electrical impulses to the circular muscles to relax and the radial muscles to expand, causing the pupil to become larger (dilate) and let more light through the eye.
Why is pupil dilation a reflex action?
It doesn’t involve the conscious part of the brain
What happens to the pupil in the presence of a lot of light?
It gets smaller to reduce damage to the - circular muscles contract and radial muscles relax
What type of focus is the Cornea?
A fixed focus
How does the lens focus on near/distant objects?
It changes shape (accommodation)
What is accommodation?
The ability of the lens to change shape to focus on near/distant objects
What happens when the Ciliary muscles contract?
The suspensory ligaments loosen and the lens becomes thick, refracting light rays more strongly
What happens when the Ciliary muscles relax?
The suspensory ligaments are pulled tight and the lens becomes more thin, only slightly refracting light rays
How much does light from distant objects need to be focused?
A relatively small amount
How much does light from nearby objects need to be focused?
A large amount
Why is accommodation useful for the eye?
It helps prevent damage to the retina
What are the general features of an automatic control system?
- Receptor cells - Detect changes in the environment (Stimulus)
- Coordination centre - Receives and processes information from receptor cells (e.g. Brain/Spine/Pancreas)
- Effector - A muscle or a gland which contracts/secretes a hormone to restore the optimum level
How are messages carried from receptor cells to the CNS?
Through electrical impulses along neurones (nerve cells)
What kind of neurones are connected to receptor cells?
Sensory neurones
Describe the reflex arc that would occur if your hand was placed on top of a flame
- Stimulus (heat) detected by receptor cells in the skin, and an electrical impulse is carried down a
sensory neurone to the CNS. - Neurotransmitters diffuse across a synapse and onto a relay neurone where it triggers an electrical
impulse - Chemical diffuses again across a synapse from a relay neurone to a motor neurone, triggering another
electrical impulse- Impulse travels across motor neurone which is connected to a muscle in the arm - causing a contraction ( pulling hand from flame)
Identify stimulus, coordination centre, effector and response pls
What makes reflexes rapid and automatic, and what are the benefits of this?
They don’t involve the conscious part of the brain, and this helps to protect us from danger
What is homeostasis?
The regulation of conditions inside the body/cells to maintain a stable internal environment, in response to changes in internal and external conditions
What is the importance of homeostasis?
It maintains the optimum conditions for cells to function properly/enzyme action
What is the function of a nervous system in animals?
It allows organisms to react to their surroundings
Explain how laser surgery can be used to correct vision defects
It changes the shape of the cornea, to change how strongly light is refracted into the eye
What new technology apart from laser surgery can offer a permanent correction for visual defects?
(What are the dangers of this)
Replacement lens surgery
Retina could become damaged/eye may become infected
