16: Coordination in Humans - Problems Flashcards
(23 cards)
The electron micrographs below show the cross sections nerve fibres X and Y.
Name layer P and state its functions. (1+2)
Myelin sheath
It insulates the nerve fibres, thus preventing the transmission of nerve impulses to the surroundings.
It speeds up the transmission of nerve impulses.
Suggest and explain the difference in speed of nerve impulse transmission in nerve fibres X and Y. (2)
The speed of nerve impulse transmission of nerve fibre X is higher than that of nerve fibre Y.
This is because nerve fibre X is myelinated but nerve fibre Y is not.
AL 2009 I Q1
With reference to one observable feature in the electron micrograph, deduce the direction of signal transmission between the two neurones. (3)
Signal transmits from neurone A to neurone B.
There is a large number of vesicles in the synaptic knob of neurone A,
which shows that A is the presynaptic neurone which releases neurotransmitter to depolarise the membrane of B.
The electron micrograph below shows a synapse between two neurones. Identify and explain the direction of nerve impulse transmission. (3)
From neurone P to neurone Q.
Synaptic vesicles containing neurotransmitters are present in the ending of neurone P only.
Neurotransmitters released from neurone P diffuse across the synaptic cleft to neurone Q and bind with the receptors in the membrane of neurone Q to stimulate neurone Q to generate a nerve impulse.
Explain the significance of the abundance of mitochondria in the neurone ending. (1)
To provide sufficient energy by aerobic respiration for the production of neurotransmitters.
Suggest the significance of involving a few neurones in a reflex arc. (1)
It helps producing fast responses to protect the body from further damage.
Describe how nerve impulses are transmitted across gap X. (4)
At first, when a nerve impulse arrives at the synaptic knob at the axon terminal of the neurone Z, the synaptic vesicles move to and fuse with the neurone Z membrane, releasing the neurotransmitters contained in the synaptic vesicles into the synaptic cleft.
Then, the neurotransmitter diffuses across gap X, which is the synaptic cleft,
and binds to the specific receptors on the membrane of the postsynaptic neurone, which is an interneurone.
Finally, this binding stimulates the dendron or cell body of the interneurone to generate a nerve impulse.
State the differences in the structure and functions of neurones Y and Z. (2)
Structure:
Y (motor neurone) has very short dendrons while Z (sensory neurone) has a long dendron. / Y has a long axon while Z has a short axon.
Function:
Y transmits nerve impulses from the spinal cord of the central nervous system to the effectors while Z transmits nerve impulses from the receptors to the spinal cord of the central nervous system.
Explain why pain is only felt after the hand is withdrawn. (2)
The nerve impulses are transmitted to the brain via another nervous pathway.
As this pathway is longer than the reflex arc and involves more synapses, pain is felt after withdrawing the hand.
Given that cranial reflex does not involve interneurones, explain the difference in the speed of spinal reflex and cranial reflex. (2)
As fewer synapses are involved in cranial reflex than in spinal reflex,
there are fewer synaptic delays and the speed of nerve impulse transmission is higher.
The diagrams below show cross sections of spinal cords across the intervertebral discs of two individuals.
State the difference in the intervertebral discs of the two individual and suggest a cause for the difference. (2)
The intervertebral disc of individual I is in the correct position while that of individual II is slipped.
Improper posture / Sports injuries / Degeneration may be a cause of the slip of the intervertebral disc.
The diagrams below show cross sections of spinal cords across the intervertebral discs of two individuals.
With reference to the diagram, suggest why individual II suffers from back pain. (2)
The slipped intervertebral disc presses against the spinal nerve.
The nerve impulses are sent along the nerve to the sensory area of the cerebrum, which produces the sensation of pain.
A patient broke her back at waist level in an accident. A doctor checked if her spinal cord was damaged by tapping gently on her hanging leg just below the knee cap. Explain the principle behind this. (2)
The spinal cord is the reflex centre for the knee jerk reflex.
If the spinal cord is damaged, the knee jerk reflex of kicking up the hanging leg will not occur when the doctor gently taps on the patient’s hanging leg just below the knee cap.
DSE 2016 IB Q1
Fill in the table.
- Medulla oblongata
- Difficulty in balance during movement
- Cerebrum
CE 2008 I Q2
The photograph below shows the lateral view of a human brain.
State the significance of the surface of structure X being highly folded. (1)
To harbour more neurones.
CE 2008 I Q2
The photograph below shows the lateral view of a human brain.
Name structure Y and state one of its functions. (2)
It is the medulla oblongata and it controls many involuntary actions like heartbeat.
The photograph below shows a section of the human cerebrum.
Space X is filled with a fluid. Name the fluid and state three functions of it. (4)
Cerebrospinal fluid
It acts as a shock absorber.
It provides mechanical support to the brain.
It provides nutrients and oxygen to the neurones and removes wastes from them.
The photograph below shows a section of the human cerebrum.
With reference to the photograph, state one feature of the surface of the cerebrum and suggest one significance. (2)
The surface of the cerebrum is highly folded.
This helps increase its capacity, enabling it to hold more neurones in a limited space.
Describe and explain the distribution of grey matter and white matter in the cerebrum. (4)
The grey matter is located in the outer part of the cerebrum.
It consists mainly of the cell bodies of neurones.
The white matter is located in the inner part of the cerebrum.
It consists of nerve fibres only.
Explain if other parts of the brain have the same distribution of grey matter and white matter as the cerebrum. (1)
No. The medulla oblongata is a part of the brain that has a different distribution of grey matter and white matter as the cerebrum. In the medulla oblongata, the grey matter is located in the inner part while the white matter is located in the outer part.
The MRI below shows the structure of the human brain.
Suggest and explain what would happen to a person whose part Y was damaged in an accident. (2)
Death may result
because many vital involuntary actions including breathing and heart beat controlled by part Y will be lost when it was damaged in an accident.
The MRI below shows the structure of the human brain.
Suggest and explain what would happen to a person whose part Z was cut along line P in an accident. (2)
Sensations from body parts below the cut cannot be produced and body parts below the cut along line P would be paralysed,
because nerve impulses sent from the receptors to the parts of the spinal cord below the cut could not be transmitted to the cerebrum for interpretation to give sensation and nerve impulses from the cerebrum could not be transmitted down to the body parts below the cut for voluntary responses.
Discuss the differences between nervous coordination and hormonal coordination in humans. Explain how these two types of coordination enable humans to respond to change properly. (7+3)
Differences between nervous coordination and hormonal coordination:
Nervous coordination involves the nervous system, whereas hormonal coordination involves the endocrine system. /
Nervous coordination involves both electrical (nerve impulses) and chemical (neurotransmitters) messages, whereas hormonal coordination involves chemical message (hormones) only. /
The message is transmitted along neurones in nervous coordination, whereas the message is transmitted along bloodstream in hormonal coordination. /
The speed of transmission is fast in nervous coordination, whereas it is slow in hormonal coordination. /
The area of response is localized in nervous coordination, whereas it is widespread in hormonal coordination. /
The duration of effects is short-lived in nervous coordination, whereas it is usually long-lasting in hormonal coordination.
How nervous coordination and hormonal coordination enable humans to respond to changes properly:
In nervous coordination, the electrical nature of nerve impulse transmission enables the body to give rapid responses to the changing conditions of the surroundings.
The localised response of nervous coordination enables specific body parts to cope with the situation.
The long-lasting effect in hormonal coordination enables the body to control long-term processes such as growth, development and reproduction
