Lecture 4: Muscle & Nerve Tissue Flashcards
What are the two types of Nerve Cells?
Neurons & Neuroglia
What is a Neural Cell?
A Cell of the Nervous System
Where does the word Neuron come from?
based on the ancient Greek neuron ‘sinew, cord, nerve’
Where does the word Neuroglia come from?
from neuro- ‘of nerves’ + Greek glia ‘glue’.
What are the subdivisions of the Nervous System?
Central nervous system (CNS): brain and spinal cord (and optic nerve)
Peripheral nervous system (PNS): all nervous tissue outside CNS
Where are Neurons found?
In both the Central Nervous System & the Peripheral Nervous System
Where are Neuroglia found?
Different types can be found in the Central Nervous System, or the Peripheral Nervous System. A singular type can not be in both.
What is the Soma?
The cell body.
Contains the nucleus and the organelles.
What is the function of Neurons?
To process and transmit information
What is the function of Neuroglia?
To support the Neurons in a variety of ways.
What is the area where the Axon leaves the Soma called?
The Axon Hillock
What are the divisions of the Peripheral Nervous System?
Sensory/afferent division: Information to the CNS.
Motor/efferent division: Information from CNS to the organs (muscles and glands).
What does the Nervous System help us do?
Maintain homeostasis (along with the endocrine system)
Initiates voluntary movements
Responsible for perception, behaviour and memory
What are the three major functions of the Nervous System?
Sensory: Detection of internal and external stimuli and transfer to CNS
Integrative: analysis and storing of information
Motor: stimulation of effectors (e.g. muscle and glands) through PNS i.e.
motor here means “effector”
What is the composition of a Neuron?
A cell body into which short, branched dendrites convey nerve impulses (action potentials) and from which a longer, single axon conducts nerve impulses to another neuron or tissue.
What is a Dendrite?
The receiving/input part of the neuron.
What is an Axon?
Carries the nerve impulse away from the neuron. It is the output portion of the neuron.
Do Neurons divide?
No.
What can’t Neurons survive without?
High metabolic rate.
(die rapidly without O2)
What are Multipolar Neurons?
Neurons with 2 or more dendrites and a single axon.
What are the most common Neuron type?
Multipolar Neurons
What Neuron type are all motor neurons?
(Control Skeletal Muscle)
Multipolar Neurons
What is the longest Neuron type?
Multipolar Neurons
Spinal cord to toe muscles
What are Bipolar Neurons?
Neurons with 1 Dendritic process (can branch at tip, but not at cell body) and 1 axon.
Has cell body between
axon and dendrite
Rare and small (30μm)
Where are Bipolar Neurons?
Special sense organs
(sight, smell, hearing)
Relay information from receptor
to neurons
What are Unipolar Neurons?
The dendrites and axon are continuous
Cell body off to one side
Whole thing from where dendrites converge called axon
Most sensory nerves are unipolar
Very long (1m) like motor nerves CNS-toe tip.
What are Anaxonic Neurons?
Rare and functions are poorly understood
Anatomy cannot distinguish dendrites from axons
Found in brain and special sense organs
What type of Nerve cells make up the majority of the volume in the CNS?
Neuroglia
Are Neurons or Neuroglia smaller
Neuroglia
Smaller than neurons but more numerous (5-50x)
Can Neuroglia propagate action potentials?
Do not propagate action potentials, but can communicate.
Can Neuroglia divide?
Can divide within the mature nervous system
