B3 Flashcards
What is the function of the pituitary gland?
Stores and releases hormones that regulate many bodily functions.
State the function of the cerebrum.
Controls complex behaviour such as learning, behaviour, conscious thoughts, personality and memory.
State the function of the medulla.
Controls automatic bodily functions such as breathing and heart rate.
State the function of the hypothalamus.
Regulates temperature and water balance.
State the function of the cerebellum.
Controls posture, balance and involuntary movements.
State the function of sensory neurones.
Carry electrical impulses from the receptor cells to the CNS.
What is the CNS?
It is made up of the brain and spinal cord.
What is the peripheral nervous system?
All of the neurones that connect the CNS to the rest of the body.
Give the 3 functions of the kidney.
To filter blood, 300 times a day.
Main organ in homeostasis.
To remove excess water, urea and other waste from the blood.
What is a nephron,
why isn’t this card working
The filtering part of the kidney. The nephron filters all small molecules out of the blood and then reabsorbed all useful substances by selective reabsorption. Anything left in the nephron becomes urine and is sent to the bladder for storage.
Define:
Hypertonic
Hypotonic
Isotonic
Hypertonic - contains high levels of glucose and salts
Hypotonic - contain low levels of glucose and salts
Isotonic - contain ion concentrations equal to those in blood plasma.
What triggers the thirst response?
A reduction in the water potential of your blood plasma, or an increase in salt concentration.
When are relay neurones used?
In reflexes. They carry electrical impulses from the sensory neurones to the motor neurones, bypassing the CNS.
Where do motor neurones carry signals to and from?
From relay neurones (in reflexes) and the CNS to effectors.
What is the purpose of the myelin sheath? Where is it found?
It is a fatty white substance that surrounds the axon of some neurons (nerve cells), forming an insulating layer. As it is insulating, it will protect nerve cells from the electrical impulses whilst also allowing those electrical impulses to pass through the neurones very quickly.
Define the synapse.
The gap between two neurones. Nerve impulse is transmitted across by neurotransmitters.
What is the axon?
It is a long extension of cytoplasm in neurons that conducts nerve impulse away from the cell body.
Give the order of the reflex arc.
Stimulus - Receptor - Sensory neuron - Relay neuron - Motor neuron - Effector - Muscle
What are receptors?
They are specialised cells that are able to detect changes in the environment and convert stimuli into electrical energy.
What are stimuli?
Anything that can trigger a physical or behavioural change.
Describe how electrical impulses are transmitted across neurones.
The connection in between two neurones is a gap called the synapse. When an electrical impulse reaches the synapse, it stimulates the release of neurotransmitter chemicals that diffuse across the gap and bind to receptors on the next neurone, which triggers a new electrical response.
Define a reflex.
Automatic responses to certain stimuli. Their function is to protect the body.
What is the function of the retina?
The part of the eye that changes light into electrical signals.
What is the purpose of the iris?
It controls the size of the pupil, a hole that allows light into the eye.
Draw and label a diagram of the eye.
check notes lol loser
Describe the cornea and explain its function.
It is a transparent coating on the front of the eye. It protects the eye and refracts light entering it.
Describe the optical nerve and explain its function.
It is nervous tissue that carries electrical nerve impulses to the brain.
Describe the lens and explain its function.
It is a transparent biconvex lens that focuses light clearly onto the retina.
Describe the ciliary body and explain its function.
It is a ring of muscle tissue underneath and above of the lens that alters the shape of the lens.
Describe the suspensory ligaments and explain their function.
They are ligament tissue that connect the lens to the ciliary muscles.
How is shortsightedness fixed?
With a concave lens that bends the light rays outwards before they enter the eye.
How is longsightedness fixed?
By a convex lens bending the light rays inwards before they enter the eye.
What are the two different kinds of photoreceptor cells that the retina has?
Rods- responsive to light levels and allows you to see in low light.
Cones - responsive to colours and allows you to see different colours.
The brain’s outer layer, the cerebral cortex, is folded into ridges and furrows. Why is this?
This increases the brain’s surface area, which in turn increases the number of neurones it can have. The more neurones a brain has, the more information it can process.
What are two methods that can be used to study the brain?
CT/CAT scans
MRI scans
Give one disadvantage and one advantage of a CAT scan.
It’s 3D, so the brain can be looked at in more detail and more realistically.
However, CAT scans use X-rays, which emit radiation, which is harmful.
Give some ethical concerns to studying the brain.
- There is often a shortage of people with certain brain disorders/diseases willing to participate in research
- Tests for brain functionality could be false and could lead to false important decisions being made with harsh consequences - e.g. taking someone off life support.
- Euthanasia is illegal in the UK
How can damage to the PNS affect the body?
- inability to detect pain
- numbness
- loss of coordination.
Explain why damage to the sensory neurones could prevent you from feeling pain.
Sensory neurones are part of the peripheral nervous system. They carry nerve impulses from receptors to the CNS. If they are damaged, it prevents this impulse from being carried to the CNS and therefore to the brain, thus resulting ub an inability to detect pain as the impulses remain undelivered and undetected by the CNS.
State how damage to the PNS is remedied.
The PNS can regenerate if it is damaged. Minor nerve damage often self-heals, and corrective surgery can take place for more serious injuries.
Why is it dangerous if the CNS is damaged?
The CNS is not able to regenerate. This can result in loss of bodily systems, partial or complete paralysis or memory loss/processing difficulties. Damage to the CNS is often extremely difficult to repair, as surgery risks damaging other parts of the CNS as many nerve fibres are closely packed together.
Define hormones.
Chemical messengers that are transported in the bloodstream to target organs.
What is the endocrine system?
It is a collection of glands that secrete hormones. It controls and coordinates body processes within the nervous system.
Define negative feedback.
A mechanism in which any change away from the normal is rectified to the normal range. E.g. temperature, blood sugar and thyroxine levels.
State two functions of the hypothalamus.
Responsible for producing hormones.
Responsible for homeostasis.
Controls temperature, thirst, hunger, and release of other hormones.
Compare nerves and hormones as messaging systems.
NERVES:
Fast transmissions
Transmitted electrically through neurones
Targets a precise area
Response is a short action.
HORMONES
Slow to transmit
Transmitted through chemicals the bloodstream
Targets organs, larger areas
Long response duration
State two causes of shortsightedness.
- Longer eyeballs.
- Lens is too strong
State two causes of long-sightedness.
- Lens too weak
- Eyeballs too short
Define homeostasis.
Keeping the conditions in the body constant.
What are target cells?
When hormones diffuse out of the blood, they bind to specific receptors for that hormone. These receptors are found on the membranes or in the cytoplasm of cells in the target organs.
