ACCESS to HE 2019-20
HEALTH PATHWAY
Nervous system
Name:
Grade: Resubmission Pass Merit Distinction
1 (1.1)
(i) Name the three main types of neurons within the human body
1Sensory neurons………………………………………………………………………………………………………
2Motor neurons…………………………………………………………………………………………………………
3Interneurons…………………………………………………………………………………………………………
(ii) Label the diagram of the motor neurons in the figure below:
(iii) Draw annotated diagrams to compare and contrast similarities and differences of the sensory and relay neurons.
Diagram
Difference
Sensory neurons are found in receptors for example eye, ear and tongue while relay neurons are found in the brain and spinal cord
Sensory neurons transmit impulses to the brain and spinal cord while relay neurons permit sensory and motor neurons to communicate.
2 (1.2)
(i) Name the two main divisions of the nervous system.
……Central Nervous system …………………………………………………………………………………………………………
…………peripheral nervous system …………………………………………………………………………………………………….
(ii) Describe the function of each of the above divisions of the nervous system.
The …central nervous system integrates sensory information and responds to it comprises two regions spinal cord serves as a channel for signals between the brain and the rest of the body. The brain integrates sensory information and organizes body functions.
.……………………………………………………………………………………………………………
The peripheral nervous system joins the central nervous system to limbs and other organs hence serving as a transmit between the brain, the spinal cord, and the rest of the body. it consists of nerves that communicate between the central nervous system and other parts of the body.
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
……………………………………………………………………………………………………………….
(iii) Evaluate how they work together to be effective in humans.
Synapse is a gap formed between the neurons allowing communication between the neurons and systems in the body. The peripheral nervous system takes information through sensory nervous then sends it into the central nervous system.
- (1.3)
(i) State the function of the sympathetic and parasympathetic nervous systems.
Sympathetic:
Controls the body’s responses to perceived threats thus stimulates the body during fight and flight response
Parasympathetic:
controls homeostasis hence responsible for stimulation of ‘rest and digestion’. it conserves energy as it slows the heart rate and increases intestinal gland activities.
(ii-a) Name and describe a specific example of a sympathetic response.
acceleration of heart rate during exercise
Constriction of blood vessels when the arteries are occluded
Reduced motility of the large intestine
(ii b) Name and describe a specific example of a parasympathetic response.
increases digestion when the body is relaxed
Decreases respiration during resting
Decrease heart rate after a stressful situation.
(iii) Analyze the similarities and differences between the two systems.
Similarities
Both are part of the nervous system.
Both originate from the spinal cord.
Both prepares the body for the physiological process such as digestion and respiration.
Both maintain homeostasis in the body.
Both consist of pre-ganglionic and post-ganglionic neurons,
differences
sympathetic nervous prepares the body for intense activity while parasympathetic nervous relaxes the body and inhibit high energy function.
Sympathetic nervousness is long and close to the spinal while parasympathetic is short and away from the spinal cord.
4 (2.1)
(i) Name the two main ions that participate in the electrical impulse transmission in neurons?
Sodium-ion
…… potassium ion…………………………………………………………………………………………
(ii) Describe where the two ions would be found in resting neurons?
… sodium is outside the cell and potassium inside the cell
(iii) Evaluate how the structures below maintain the resting potential of a cell.
…for every ATP hydrolyzed three sodium ions move out of the neuron and two potassium ions into the neuron. The sodium-potassium pump maintains its concentration gradient which controls the resting membrane potential.
5 (2.2)
(i) Define the term ‘action potential’.
This is the fall and rise in membrane voltage which is generated when the membrane is depolarized beyond the threshold value
(ii) Outline the three requirements needed for an action potential to occur.
…………………………………………………………………………………………………………
The threshold voltage
Stimulus
Depolarized membrane
(iii) Label and describe the diagram below and use your knowledge to describe what happens in
a neuron during an action potential.
1.resting state
- threshold
3.. Depolarization
4.repolarization …………………………….
5.undershoot …………………………….
Figure 1: Action potential (www.study.com)
6 (2.3)
- i) Define the term synapse?
This is the anatomically specialized junction between two neurons where one neuron alters the electric activity of another.
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
- ii) Label the diagram of the
Figure 2: Structure of a synapse (www.dumielauxepices.net)
1 mitochondrion ……………………………………. 4 synaptic clefts…………………………………….
2 synaptic vessel……………………………………. 5 post-synaptic membranes…………………………………….
3 presynaptic membrane……………………………………. 6 presynaptic knobs…………………………………….
iii) Explain how the impulse crosses a synapse.
………The arrival of action potential depolarizes the presynaptic membrane increase permeability of calcium to penetrate through calcium ion channel increase in calcium electro gradient triggers presynaptic membrane and synaptic vessel to fuse and neurotransmitters are released to the synaptic cleft by exocytosis .neurotransmitters penetrate postsynaptic membrane and binds to the receptor ………………………………………………………………………………………………………
……………………………………