Human Biology Unit 3
Study online at https://quizlet.com/_jobhf8
1. Properties of ner- -Integrated communication network and control centre of the body.
vous tissue -Coordinates all voluntary an involuntary actions.
-Maintains homeostasis
2. Sensory (afferent) -Carry nerve impulses from receptors in sensory organs to the CNS
neurons -Collects information
3. Motor (efferent) -Carries impulses away from the CNS to effectors, such as muscles of glands
neurons -Muscle cells then carry out a response
4. Interneuron Links the sensory and motor neurons
5. Myelin -The layer of fatty material that covers the axons
-Formed by specialised cells called Schwann cells which wrap around the axon
6. Myelin functions -acts as an insulator
-protects axon from damage
-speeds up movement of the nerve impulses
, Human Biology Unit 3
Study online at https://quizlet.com/_jobhf8
7. Polarisation -the cell membrane is very permeable to K+ and only slightly permeable to Na+.
Large negative ions inside the membrane do not diffuse
-As K+ diffuses out, the inside of the nerve fibre becomes electrically negative
-stimulus changes the permeability of the cell
8. Depolarisation -Intake of Na+ is greater than outtake of K+
-All or none response
9. Refractory period The time following an action potential during which a new action potential
cannot be initiated
10. Saltatory conduc- -In myelinated fibres, the nerve fibres are insulated from the extracellular fluid
tion except at the nodes of Ranvier. Therefore, ions cannot diffuse in and out of the
cell and an action potential cannot form.
-A means by which action potentials jump from node to node along an axon.
11. Synapse the junction between two neurons, or between a neuron and a muscle gland
, Human Biology Unit 3
Study online at https://quizlet.com/_jobhf8
12. Neuromuscular the synapse between an axon and a skeletal muscle fibre.
junction
13. Motor end plate occurs when the axon terminal ends in a muscle group
14. Dorsal root contains axons of sensory neurons that have their cell bodies in a small swelling
known as the DR ganglion
15. Ventral root contains axons of motor neurons that have their cell bodies in the grey matter
of the spinal cord.
16. Grey matter centre of the spinal cord; outside of the brain. Composed of nerve cell bodies
and unmyelinated fibres
17. White matter Outer area of spinal cord; inside of brain. Composed of myelinated fibres
18. Spinal cord a roughly cylindrical structure that extends from the foramen magnum to the
2nd lumbar vertebrae
Study online at https://quizlet.com/_jobhf8
1. Properties of ner- -Integrated communication network and control centre of the body.
vous tissue -Coordinates all voluntary an involuntary actions.
-Maintains homeostasis
2. Sensory (afferent) -Carry nerve impulses from receptors in sensory organs to the CNS
neurons -Collects information
3. Motor (efferent) -Carries impulses away from the CNS to effectors, such as muscles of glands
neurons -Muscle cells then carry out a response
4. Interneuron Links the sensory and motor neurons
5. Myelin -The layer of fatty material that covers the axons
-Formed by specialised cells called Schwann cells which wrap around the axon
6. Myelin functions -acts as an insulator
-protects axon from damage
-speeds up movement of the nerve impulses
, Human Biology Unit 3
Study online at https://quizlet.com/_jobhf8
7. Polarisation -the cell membrane is very permeable to K+ and only slightly permeable to Na+.
Large negative ions inside the membrane do not diffuse
-As K+ diffuses out, the inside of the nerve fibre becomes electrically negative
-stimulus changes the permeability of the cell
8. Depolarisation -Intake of Na+ is greater than outtake of K+
-All or none response
9. Refractory period The time following an action potential during which a new action potential
cannot be initiated
10. Saltatory conduc- -In myelinated fibres, the nerve fibres are insulated from the extracellular fluid
tion except at the nodes of Ranvier. Therefore, ions cannot diffuse in and out of the
cell and an action potential cannot form.
-A means by which action potentials jump from node to node along an axon.
11. Synapse the junction between two neurons, or between a neuron and a muscle gland
, Human Biology Unit 3
Study online at https://quizlet.com/_jobhf8
12. Neuromuscular the synapse between an axon and a skeletal muscle fibre.
junction
13. Motor end plate occurs when the axon terminal ends in a muscle group
14. Dorsal root contains axons of sensory neurons that have their cell bodies in a small swelling
known as the DR ganglion
15. Ventral root contains axons of motor neurons that have their cell bodies in the grey matter
of the spinal cord.
16. Grey matter centre of the spinal cord; outside of the brain. Composed of nerve cell bodies
and unmyelinated fibres
17. White matter Outer area of spinal cord; inside of brain. Composed of myelinated fibres
18. Spinal cord a roughly cylindrical structure that extends from the foramen magnum to the
2nd lumbar vertebrae
