Nervous System 1 - Introduction Flashcards
Identify the subdivisions of the nervous system?
List the basic functions of the nervous system?
Sensory Input:
Sensory receptors detect internal & external stimuli.
Integration:
Processes and interprets sensory input and decides what should be done at each moment.
Motor Output:
The nervous system causes an appropriate response by activating effector organs (muscles and/or glands).
What is the role of sensory & afferent neurons?
Sensory afferent neurons:
Carry this information via the cranial and spinal nerves to the brain and spinal cord.
Motor afferent neurons:
Motor efferent neurons carry this information from the brain and spinal cord to effector organs via the cranial and spinal nerves.
Label this image of the nervous system?
What is the role of the CNS and where is it located?
Role:
The command centre of the nervous system that integrates and processes nervous information.
Location:
Protected by the dorsal body cavities:
- Brain is housed within the skull, - Spinal cord is housed within the vertebral canal.
What does the CNS include and where are they located?
Nuclei:
- Collections of specialised neuronal cell bodies.
- Located within the grey matter of the brain and spinal cord.
Fibre tracts:
- Bundles of axons within the white matter of the brain and spinal cord.
What are nerves within the PNS and how many pairs of nerves are there in the body?
Nerves:
- Bundles of axons that extend from the brain (cranial nerves) and spinal cord (spinal nerves).
- 12 pairs of cranial nerves exiting from the skull foramina.
- 31 pairs of spinal nerves exiting from the intervertebral foramina.
What are plexuses?
- Plexuses are networks of nerves.
- Main plexuses = cervical, brachial, lumbar, sacral and enteric.
- Plexuses give off terminal branches that innervate body structures.
What is ganglia, where are they located and what are their function?
What is ganglia:
Collections of neuronal cell bodies located outside the CNS.
Location:
Found throughout the body.
Function:
Carry nerve signals to and from the CNS.
What is the sensory (afferent) nervous system responsible for?
Detects stimuli and transmits information from sensory receptors to the CNS.
***Afferent = input.
What are the 2 subdivisions of the sensory nervous system?
Somatic sensory subdivision.
Autonomic (visceral) sensory subdivision.
What is the somatic sensory subdivision responsible for and what is its main function?
- Responsible for sensory input that is consciously perceived from sensory receptors
*** Voluntary functions.
What are examples of what the somatic sensory subdivision transmits?
- The general somatic senses (touch, pressure, vibration, temperature and proprioception).
- The special senses (vision, hearing, balance and smell).
What is the autonomic (visceral) sensory subdivision responsible for and what is its main function?
- Responsible for sensory input that is not consciously perceived from sensory receptors in viscera.
*** Involuntary functions.
What are examples of what the autonomic (visceral) sensory subdivision transmits?
- Stretch of an organ wall (e.g. wall).
What is the motor (efferent) nervous system responsible for?
Responsible for transmitting motor impulses from the CNS to effectors (muscles or glands).
***Efferent = output.
What are the 2 subdivisions of the motor (efferent) nervous system?
Somatic motor subdivision
Autonomic (visceral) motor subdivision
What is the somatic motor division responsible for and what is its main general function?
- Responsible for motor output that is consciously or voluntarily controlled.
*** Voluntary functions.
What is the autonomic (visceral) motor subdivision responsible for and what is its main general function?
- Responsible for motor output that is not consciously or is involuntarily controlled.
*** Involuntary functions.
Describe the basic characteristics of neurons?
H
E
High metabolic rate:
Their survival depends on the continuous and abundant supply of glucose and oxygen.
Extreme longevity:
Neurons functions optimally for a lifetime.
Describe the basic characteristics of neurons?
E
EC
Excitable:
Neurons respond to stimuli such as chemicals, stretch or pressure changes.
Exhibit conductivity:
Electrical charge is quickly propagated along their plasma membrane.
Describe the basic characteristics of neurons?
N
Nonmitotic:
Since neurons are the communicating links of the nervous system, most lose their ability to divide and produce new neurons.
Label the structural component of a neuron?
What do all neurons contain?
A cell body, an axon and one or more slender processes called dendrites.
What are dendrites responsible for?
They are responsible for receiving signals from other neurons (i.e. conducting electrical signals from other neurons towards the cell body).
*** More dendrites = more information that neuron can receive.
What does the cell body of neurons contain?
The cell body contains the typical organelles found in all cells (rich in mitochondria, ribosomes and rough ER).
What are clusters of neuronal cell bodies called inside and outside the CNS called?
Inside = nuclei.
Outside = ganglia.
What is the function of an axon in a neuron?
It generates nerve impulses and transmits them away from the cell body towards another cell.
What is the function of the whitish, fatty, segmented myelin sheath that covers an axon?
This protects and electrically insulates axons and increases the speed of nerve impulse transmission along them.
What are the 2 types of axons and how do they conduct nerve impulses?
Myelinated axons:
Conduct nerve impulses rapidly.
Unmyelinated axons:
Conduct impulses more slowly.
Label photomicrograph of a large motor neuron below?
What are the 3 structural types of neurons and give a brief description of them?
Multipolar:
Have many processes - one axon and many dendrites.
Unipolar:
Have a single short process.
Bipolar:
Have two processes - and axon and one dendrite.
Finish the sentence:
All motor neurons are _________.
Most sensory neurons are __________.
- Multipolar
- Unipolar
What are the 2 types of multipolar neurons and what are their function?
Motor neurons:
All of these conduct impulses along efferent pathways.
Interneurons:
Conduct impulses within the CNS.
What is the function of unipolar neurons and where do they divide into?
- Conduct impulses along afferent pathways.
- These neurons have a single short process that divides into peripheral (towards sensory receptor) and central (entering CNS) branches.
Where are the rare bipolar neurons found?
Found only in some special sense organs – the retina of the eye and the olfactory epithelium in the nasal cavity.
Label the parts of the 3 structural types of a neuron?
What are the 3 types of neurons?
Sensory neurons
Motor neurons
Interneurons
Give a brief explanation of sensory neurons?
- Are afferent neurons that transmit nerve impulses from sensory receptors to the CNS.
- Most are unipolar, except for those in the retina of the eye and in the olfactory epithelium in the nasal cavity, which are bipolar.
Give a brief explanation of motor neurons?
- Are efferent neurons that transmit nerve impulses from the CNS to effectors (muscles or glands).
- All motor neurons are multipolar.
Give a brief explanation of interneurons?
- They receive impulses from many other neurons and carry out the integrative function of nervous system.
- All interneurons are multipolar.
Identify the 4 types of neuroglia found in the CNS?
Identify the 2 types of neuroglia found in the PNS?
Describe the major function of neuroglia in the CNS and PNS?
Microglial cells = monitor the health of neurons by defending against pathogens.
Astrocyte = provides structural support.
Ependeymal cells = assist in the production and circulation of CSF.
Oligodendrocyte = myelinate CNS axons (greater impulse conduction).
Satellie cells = regulate nutrients for the cell bodies in ganglia.
Schwann cells = myelinate CNS axons (greater impulse conduction).
What part of the autonomic nervous system leads to the ‘fight or flight’ response and the ‘rest and digest’ response?
Fight or flight = sympathetic nervous system.
Rest and digest = parasympathetic nervous system.
What part of the nervous system located within the intestinal wall controls digestive function through local reflexes.
Enteric nervous system
