SCSA Human Biology Central and peripheral nervous system
15 sample questions with marking guides and sample answers · Avg. score: 71.9%
While the nervous and endocrine systems work together to co-ordinate the functions of the body systems, they differ in several ways. Contrast three ways in which these systems operate.
Reveal Answer
Answers could include:
- The nervous system is rapid while the endocrine system is slower.
- Nervous system work along neurons while endocrine system works via the blood stream.
- Nervous system responses are usually local and specific to one effector, while endocrine system may be very general and widespread.
| Descriptor | Marks |
|---|---|
2 marks for each correct point (any 3 of):
| 6 |
The autonomic nervous system helps to control homeostatic mechanisms. The effects of these can often be demonstrated consciously. For example, an athlete competing in an important race event noticed the following whilst standing waiting for the race to start; they had a 'funny feeling' in their stomach, they were sweating, the light seemed brighter than usual, and they felt their heart was going to explode.
Outline the neural pathway of the autonomic nervous system activated in the athlete and explain the reasons for these symptoms.
Reveal Answer
The pathway involved is the sympathetic pathway.
Neurons originate in the middle region of the spinal cord, specifically the thoracic and lumbar regions, and leave the spinal cord via the ventral root. They synapse close to the spinal cord with the next neuron, the postganglionic fibre, and release noradrenaline to effect the target organ, involving two motor neurons and one synapse.
The reasons for these responses are to prepare the body for physical work and the activation of fight or flight responses. Sweating was because of the activation of sweat glands to keep the body cool during physical activity. The stomach feeling was due to decreased movement of digestive organs, to divert blood and energy to other parts of the body that need it more. Light changes were due to the dilation of the pupil to allow for more precise vision. The heart racing was due to an increased rate and strength of heart contractions to ensure enough blood and energy is being pumped to vital organs and muscles.
| Descriptor | Marks |
|---|---|
Identifies the sympathetic pathway | 1 |
1 mark for each correct point (any 3 of): neurons originate in the middle region of the spinal cord (thoracic and lumbar); neurons leave spinal cord via ventral root; synapse close to spinal cord with next neuron (postganglionic fibre); release noradrenaline to effect target organ; two motor neurons and one synapse | 3 |
Explains that the responses prepare the body for physical work | 1 |
States that this is the activation of fight or flight responses, protects the body from harm, or acts as lifesaving mechanisms | 1 |
Explains that sweating was because of the activation of sweat glands | 1 |
States that this is to keep the body cool during physical activity | 1 |
Explains that the stomach feeling was due to decreased movement of digestive organs or intestinal arterioles constricting | 1 |
States that this is to divert blood or energy to other parts of the body that need it more | 1 |
Explains that light changes were due to the dilation of the pupil | 1 |
States that this allows for more precise vision or the ability to interpret visual stimuli | 1 |
Explains that the heart racing was due to an increased rate or strength of heart contractions | 1 |
States that this ensures enough blood or energy is being pumped to vital organs or muscles | 1 |
Blind people are taught to read Braille (raised marks that create patterns on paper). They do this by running their fingertips over the markings. The pathway the impulse travels from the fingers to the brain includes some of the following components:
I. touch receptors
II. connector neuron
III. motor neuron
IV. sensory neuron
V. thalamus to cerebrum
VI. thalamus to cerebellum.
The correct order of the components in the pathway is
IV - II - III - VI
I - IV - II - V
III - II - IV - V
I - II - V - VI
Reveal Answer
IV - II - III - VI
This pathway skips the touch receptors, incorrectly includes a motor neuron (which carries signals away from the brain), and ends in the cerebellum rather than the cerebrum.
I - IV - II - V
The sensory pathway begins with touch receptors (I), travels via sensory neurons (IV) to connector neurons (II) in the CNS, and is relayed through the thalamus to the cerebrum (V) for conscious perception.
III - II - IV - V
This pathway incorrectly begins with a motor neuron, which carries impulses from the brain to muscles, rather than transmitting sensory information to the brain.
I - II - V - VI
This pathway skips the sensory neuron needed to carry the signal from the receptors to the CNS, and incorrectly includes the cerebellum, which coordinates movement rather than processing conscious touch.
Chemoreceptors monitor the level of gases in the body and can be found in all areas
listed except the
carotid body.
aortic arch.
nose.
brain.
Reveal Answer
carotid body.
Peripheral chemoreceptors that monitor oxygen and carbon dioxide levels in the blood are specifically located in the carotid bodies.
aortic arch.
The aortic arch contains peripheral chemoreceptors that detect changes in blood gas concentrations to help regulate respiration.
nose.
While the nose contains olfactory chemoreceptors for smell, it does not contain the chemoreceptors responsible for monitoring internal blood gas levels like oxygen and carbon dioxide.
brain.
Central chemoreceptors are located in the brain, specifically the medulla oblongata, where they monitor carbon dioxide and pH levels in the cerebrospinal fluid.
Flynn was standing at second base during a game of baseball. The batter hit the ball straight at him. Without thinking, Flynn put his baseball glove up to stop the ball from hitting his face and his face flinched (involuntarily turned) away from the incoming ball.
Describe the components of the mechanism that produced the flinching response.
Reveal Answer
It is a reflex action so it only involves the spinal cord. Impulse travels from receptor to sponal cord via a sensory neuron through the dorsal root.
Synapse between a sensory neuron and an interneuron in the grey matter of the spinal cord. Synapse between interneuron and motor neuron. And impulse is sent to effector through ventral root. Motor neuron stimulates muscle movement via a neuromuscular junction.
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 8 of): Reflex action (so only involves the spinal cord); Impulse travels from receptor to spinal cord; via a sensory/afferent neuron; through the dorsal root; Synapse between a sensory/afferent neuron and an interneuron; In the grey matter of the spinal cord; Synapse between interneuron and motor/efferent neuron; Impulse sent to effector through ventral root; Motor/efferent neuron stimulates muscle movement; via a neuromuscular junction/across a motor end plate | 8 |
Explain how a nerve impulse travels along an axon and between neurons.
Reveal Answer
Along the axon:
Depolarisation occurs and reaches threshold. Cell membrane becomes permeable to sodium ions, which diffuse into the cell across the cell membrane. Potassium ions diffuse out of the cell across the membrane. Inside the membrane becomes negative relative to the outside. A sodium-potassium pump transport sodium ions out of the cell transports potassium into the cell. The neuron is repolarised.
Between the neurons:
Action potential reaches axon terminal. Calcium channels open and calcium causes vesicles to release neurotransmitter via exocytosis. Neurotransmitters bind to neuroreceptors on post synaptic dendrite, and action potential triggerred in post synaptic neuron.
Along the axon
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 7 of): Depolarisation occurs; Reaches threshold/-55 mV; Cell membrane becomes permeable to sodium ions/sodium channels open; Sodium ions diffuse into the cell (across the cell membrane); Inside the cell/membrane becomes positive relative to the outside; Potassium ions diffuse out of the cell (across the membrane)/potassium channels open; Inside the membrane becomes negative relative to the outside; A sodium–potassium pump transports sodium ions out of the cell transports potassium ions into the cell; Returns to a polarised/resting state/neuron repolarised | 7 |
Between neurons
| Descriptor | Marks |
|---|---|
1 mark for each correct point (any 5 of): Action potential reaches axon terminal; Calcium channels open; Calcium causes vesicles to release neurotransmitter (via exocytosis); Neurotransmitter diffuses across synaptic cleft; Neurotransmitters binds to (neuro)receptors on post synaptic dendrite; Action potential triggered in post synaptic neuron | 5 |
Homeostatic response mechanisms require the transfer and recognition of information from a sensory receptor and an effector. The transmission of this information
may involve both the endocrine and nervous systems.
relies only on hormones for a short-term response.
is usually a conscious process.
is under control of the autonomic system only.
Reveal Answer
may involve both the endocrine and nervous systems.
This is correct because homeostasis often relies on the integration of both the nervous system for rapid responses and the endocrine system for sustained, long-term regulation.
relies only on hormones for a short-term response.
This is incorrect because hormones, which are part of the endocrine system, typically mediate slower, long-term responses, whereas the nervous system handles rapid, short-term responses.
is usually a conscious process.
This is incorrect because homeostatic mechanisms, such as regulating blood glucose or body temperature, are primarily involuntary and unconscious processes.
is under control of the autonomic system only.
This is incorrect because homeostasis involves multiple systems, including the endocrine system and occasionally the somatic nervous system (such as shivering), not just the autonomic nervous system.
Some organs are under both nervous and hormonal control. When being stimulated by hormones, you would generally expect the response to be
specific in action, long-lasting, but slow to start.
rapid, brief and widespread in action.
slower, longer-lasting and general in nature.
local in action, long-lasting and takes only seconds to act.
Reveal Answer
specific in action, long-lasting, but slow to start.
While hormonal responses are long-lasting and slow to start, they are typically widespread rather than highly specific or localized in their action.
rapid, brief and widespread in action.
Rapid and brief responses are characteristic of the nervous system, which uses fast-traveling electrical impulses, not the hormonal system.
slower, longer-lasting and general in nature.
Hormones travel through the bloodstream, making their effects slower to initiate, longer-lasting, and more widespread (general) compared to nervous system responses.
local in action, long-lasting and takes only seconds to act.
Hormonal responses are generally widespread rather than local, and they typically take minutes to days to act, rather than just seconds.
The following is a list of statements related to the effects of the autonomic nervous system:
I. increases rate and strength of contractions of the heart
II. increases sweat secretion
III. constricts pupils
IV. stimulates hormone secretion from the adrenal medulla
V. increases movement of the stomach and intestines.
Which of the following identifies the effects that are brought about by the sympathetic division of the autonomic nervous system?
I, II, IV and V only
I, II, III and V only
I, II and IV only
III and V only
Reveal Answer
I, II, IV and V only
While statements I, II, and IV are sympathetic effects, statement V (increased digestive movement) is a parasympathetic effect. The sympathetic nervous system inhibits digestion during "fight or flight" responses.
I, II, III and V only
This option incorrectly includes statements III (pupil constriction) and V (increased digestive movement), which are both parasympathetic "rest and digest" functions. The sympathetic nervous system actually dilates pupils and inhibits digestion.
I, II and IV only
The sympathetic nervous system drives the "fight or flight" response, which includes increasing heart rate and contraction strength (I), stimulating sweat secretion (II), and triggering the adrenal medulla to release hormones like epinephrine (IV).
III and V only
Statements III (pupil constriction) and V (increased digestive movement) describe effects of the parasympathetic nervous system, which promotes "rest and digest" activities, rather than the sympathetic division.
Which of the following statements about the meninges is correct?
They are membranes
that surround the axon of a neuron.
and fluids found around the brain and spinal cord.
that cover and protect the brain.
that are not found around the lower spinal cord.
Reveal Answer
that surround the axon of a neuron.
Incorrect. The myelin sheath, not the meninges, is the membrane structure that surrounds the axon of a neuron to insulate it.
and fluids found around the brain and spinal cord.
Incorrect. While cerebrospinal fluid is found between the meningeal layers, the meninges themselves are strictly the protective membranes, not the fluids.
that cover and protect the brain.
Correct. The meninges consist of three membranous layers (dura mater, arachnoid mater, and pia mater) that cover and protect the central nervous system, including the brain.
that are not found around the lower spinal cord.
Incorrect. The meninges cover the entire central nervous system, which includes both the brain and the entire length of the spinal cord.
Where are receptors X located?
skin and hypothalamus
carotid artery and aorta
carotid artery and hypothalamus
aorta and cerebellum
Reveal Answer
skin and hypothalamus
The skin and hypothalamus primarily contain thermoreceptors for temperature regulation, not the blood-monitoring receptors found in the cardiovascular system.
carotid artery and aorta
Peripheral chemoreceptors (which monitor blood gases and pH) and baroreceptors (which monitor blood pressure) are located in the carotid arteries and the aortic arch.
carotid artery and hypothalamus
While the carotid artery contains blood-monitoring receptors, the hypothalamus primarily houses osmoreceptors and central thermoreceptors.
aorta and cerebellum
The aorta contains blood-monitoring receptors, but the cerebellum is a brain region responsible for motor coordination, not cardiovascular monitoring.
The single, long process of a neuron that delivers signals, is termed a/an
axon.
axon terminal.
Schwann cell.
dendrite.
Reveal Answer
axon.
The axon is the single, long projection of a neuron that conducts electrical impulses away from the cell body to transmit signals to other cells.
axon terminal.
The axon terminal is the specialized ending of the axon where neurotransmitters are released, not the long process itself.
Schwann cell.
Schwann cells are a type of glial cell that wrap around axons to form the myelin sheath in the peripheral nervous system; they are not part of the neuron itself.
dendrite.
Dendrites are typically multiple, shorter, branched processes that receive signals from other neurons and carry them toward the cell body.
Which of the following is a response when the parasympathetic nervous system is activated?
increased heart rate and breathing rate
pupil dilation
increased activity of the gastrointestinal tract
vasodilation of blood vessels in the skin
Reveal Answer
increased heart rate and breathing rate
Increased heart and breathing rates are 'fight or flight' responses triggered by the sympathetic nervous system, whereas the parasympathetic system slows these rates down.
pupil dilation
Pupil dilation is a sympathetic response designed to let more light into the eyes during a threat. The parasympathetic system causes pupils to constrict.
increased activity of the gastrointestinal tract
The parasympathetic nervous system controls 'rest and digest' functions, which includes stimulating digestion and increasing gastrointestinal motility and secretions.
vasodilation of blood vessels in the skin
Blood vessels in the skin are primarily controlled by the sympathetic nervous system. Vasodilation in the skin usually occurs due to a decrease in sympathetic activity rather than parasympathetic activation.
The difference between grey and white matter found within the spinal cord is that
white matter contains dendrites of neurons, while grey matter contains cell bodies
of neurons.
grey matter contains unmyelinated neurons, while white matter contains
myelinated neurons.
white matter contains cell bodies of neurons, while grey matter contains dendrites
of neurons.
grey matter contains myelinated neurons, while white matter contains
unmyelinated neurons.
Reveal Answer
white matter contains dendrites of neurons, while grey matter contains cell bodies
of neurons.
This is incorrect because white matter primarily consists of myelinated axons, not dendrites. Grey matter is the region that contains the cell bodies and dendrites of neurons.
grey matter contains unmyelinated neurons, while white matter contains
myelinated neurons.
This is correct because white matter gets its characteristic color from the lipid-rich myelin sheaths surrounding axons. Grey matter lacks this myelin and consists largely of unmyelinated cell bodies and dendrites.
white matter contains cell bodies of neurons, while grey matter contains dendrites
of neurons.
This is incorrect because white matter does not contain cell bodies; it is composed of myelinated axons. Cell bodies are actually found within the grey matter.
grey matter contains myelinated neurons, while white matter contains
unmyelinated neurons.
This is incorrect because it reverses the relationship. Myelin is a white, fatty substance, meaning myelinated axons make up the white matter, while unmyelinated structures make up the grey matter.
Cochlear implants assist with hearing. The following are five steps involved in the process.
- The sound signal is turned into electrical impulses.
- The implant sends electrical impulses to the electrodes in the cochlea.
- Sounds are picked up by the microphone.
- The auditory nerve picks up and sends electrical impulses to the brain.
- The electrical impulses are transmitted across the skin to the implant.
Which is the correct order for this process?
1, 4, 3, 2, 5
1, 3, 2, 4, 5
3, 1, 5, 2, 4
3, 1, 2, 5, 4
Reveal Answer
1, 4, 3, 2, 5
This sequence is incorrect because the process must begin with the microphone picking up sounds (step 3) before they can be converted into electrical impulses.
1, 3, 2, 4, 5
This sequence is incorrect because it starts with converting signals to impulses (step 1) rather than first picking up the sound with the microphone (step 3).
3, 1, 5, 2, 4
This is the correct sequence: the microphone picks up sound (3), converts it to electrical impulses (1), transmits it across the skin to the implant (5), which sends it to the cochlea (2), and finally the auditory nerve sends it to the brain (4).
3, 1, 2, 5, 4
This sequence is incorrect because the electrical impulses must be transmitted across the skin to the implant (step 5) before the implant can send them to the electrodes in the cochlea (step 2).
A person felt an itch on their left arm and used their right hand to scratch it. Which of the following best describes the pathway of this message in the nervous system?
afferent peripheral nervous system efferent via autonomic neurons
efferent central nervous system afferent via somatic neurons
afferent central nervous system efferent via somatic neurons
efferent peripheral nervous system afferent via autonomic neurons
Reveal Answer
afferent peripheral nervous system efferent via autonomic neurons
The signal must be processed by the central nervous system, and scratching is a voluntary movement controlled by somatic neurons, not autonomic (involuntary) neurons.
efferent central nervous system afferent via somatic neurons
Sensory input travels via afferent neurons to the CNS, and motor output travels via efferent neurons. This option reverses the direction of the neural pathway.
afferent central nervous system efferent via somatic neurons
The sensation of the itch travels via afferent (sensory) neurons to the central nervous system, which processes the information and sends a voluntary motor command via efferent (motor) somatic neurons to scratch the itch.
efferent peripheral nervous system afferent via autonomic neurons
This option reverses the roles of afferent and efferent neurons and incorrectly identifies the motor response as autonomic (involuntary) rather than somatic (voluntary).
The myelin sheath is
fatty tissue that speeds up the neural impulse through the cell body.
grey matter that changes up the neural impulse along a dendrite.
white matter that reduces the speed of a neural impulse along an axon.
fatty tissue that speeds up the neural impulse along sections of the axon.
Reveal Answer
fatty tissue that speeds up the neural impulse through the cell body.
While the myelin sheath is indeed made of fatty tissue, it insulates the axon to speed up impulses, not the cell body.
grey matter that changes up the neural impulse along a dendrite.
The myelin sheath is composed of fatty tissue (which makes up white matter, not grey matter) and it surrounds the axon, not the dendrites.
white matter that reduces the speed of a neural impulse along an axon.
Although myelin is considered white matter, its primary function is to significantly increase, rather than reduce, the speed of neural impulses.
fatty tissue that speeds up the neural impulse along sections of the axon.
The myelin sheath is a layer of fatty tissue that insulates sections of the axon, allowing electrical impulses to transmit quickly and efficiently via saltatory conduction.