Nerves Flashcards
What are the 3 functions of the nervous system?
- Uses sensory receptors to monitor changes occurring inside and outside of the body. Each change is called a stimulus, gathering info = sensory input
- Processes and interprets the sensory input and makes decisions about should be done at each moment = integration
- Dictates a response by activating the effector organs (muscles and glands) = motor output
What are the two main divisions of the NS?
Central & Peripheral NS
What is contained within the central NS
brain & spinal cord, the integrative and control centres
What is contained in the peripheral NS
cranial and spinal nerves and ganglia, communication lines between the CNS and rest of the body
Where are the ganglia?
areas where the cell bodies of neurons are clustered
What type of nerves is in the sensory (afferent) division? What direction does the impulse travel?Give 2 examples
somatic and visceral sensory nerve fibres. Conducts impulses from receptor to the CNS. ex: skin is somatic and stomach is visceral
What type of nerve is in the motor (efferent) division? What direction does the impulse travel?
motor nerve fibers
conduct impulses from CNS to effectors (muscles and glands)
What are the two subdivisions of the motor (efferent) division?
Somatic and autonomic
T or F: The somatic nervous system is involuntary motor ?
FALSE. It is voluntary. Conducts impulses from CNS to skeletal muscles
The autonomic NS is…
And conducts impulses from the CNS to the… (3)
visceral motor (involuntary) cardiac muscles, smooth muscles, and glands
What are the 2 divisions of the autonomic nervous system?
The sympathetic and parasympathetic
What does the sympathetic division do?
Mobilize body systems during activity.
What does the parasympathetic division do?
conserve energy and promote house keeping functions during rest
What are two special somatic sensory senses?
Hearing & vision
What are two special visceral sensory senses?
taste and smell
T or F: Neuroglia are support cells
True. They are non-excitable and wrap around the neurons
Neurons are…
excitable nerve cells that transmit electrical signals
4 Functional characteristics of neurons
Conduct electrical signals
Extreme longevity
No mitosis
High metabolic rate
The cell body of a neuron is also called the…
soma
Other than the nucleus and cytoplasm, what does the cell body contain? (2)
- Neurofibrils = bundles of intermediate fibres that keep the cell from being stretched apart with tensile forces
- Chromatophilic substance = rough endoplasmic reticulum and ribosomes that stain darkly
Most cell bodies are within the CNS, but some are in the…
PNS with the ganglion
Dendrites branch from the cell body and are…
receptive sites for signals, carried to cell body
Axons (3)
- Thin, uniform diameter
- Transmit signals away from the cell body
- Actin microfilaments and microtubules carry substances
Axon collaterals
branches that extend out from the axon at right angles
Terminal arborization
branches at the end of the axon
Terminal boutons
the ends of terminal arborization/secretory region
The axon hillock is the…
impulse generating/conducting region
What is a synapse?
site of neural communication
Axodendritic synapse
occur between one neuron and the dendrite of another neuron
axiomatic synapse
occur between axons and neuron cell bodies
what is a multipolar neuron
most common, many processes ententes from the cell body all of which are dendrites except the axon
bipolar neuron
2 processes leave, one is a fused dendrite and the other is an axon
unipolar neuron
One process extends from the body and comprises the axon
Sensory neurons/afferent neurons (4)
- Make up the sensory division fo the PNS
- Transmit towards the CNS
- Most are pseudo unipolar with cell bodies in ganglia outside of the CNS
- called primary or first order neurons
Motor neurons/efferent neurons (3)
- Make up motor division of PNS
- Carry impulses away from the CNS to effector organs
- Multipolar, with cell bodies in the CNS
Interneurons
- Between motor and sensory neurons
- confined to CNS
- multipolar
What neuronglia are in the CNS? (4)
- Astrocytes
- Microglial cells
- Ependymal cells
- Oligodendrocytes
What neuroglia are in the PNS? (2)
- Satellite cells
* Schwann cells
Astrocytes (3)
Star shaped, most abundant
• Regulate neurotransmitter levels, metabolites
• Signalling increased blood flow
• Controlling ionic environment
Microglial Cells
smallest, least abundant, elongated cell body with multiple projections
• Phagocytes
• Macrophages of the CNS
Ependymal cells
- single epithelium that lines the CNS (central cavity of the spinal cord and brain)
- Move cerebrospinal fluid
Oligodendrocytes
• Produce myelin sheaths in the CNS,
Satellite cells
surround neuron cell bodies within ganglia
Schwann cells
surround all axons in the PNS and form myelin sheath
Gray matter of the CNS (6)
- Surround the hollow central cavity of CNS
- Site where neuron cell bodies are clustered
- Synapses occur here
- short nonmyelinated interneurons and motor neurons
- Has cell bodies of interneurons and motor neurons
- Neuroglia
White matter of the CNS (3)
- Fiber tracts of myelinated (gives white color) and nonmyelinated axons; no cell bodies
- Neuroglia
- Axons travelling to similar tracts are called tracts
Endoneurium
layer of loose connective tissue covering Shwann cells (myelin sheath)
Perineurium
wraps around nerve fascicles
Epineurium
tough fibrous sheath that surrounds the entire nerve
What is neuronal integration?
Communication between the CNS and PNS
Where does neuronal integration occur?
in the gray matter
What are reflex arcs?
simple chains of neurons that cause our simplest, reflexive behaviours and reflect the basic structural plan of the NS \
What are the 5 essential components of reflex arcs?
- receptor
- sensory neuron
- integration center
- motor neuron
- effector
What are 2 examples of the reflex arc?
- Monosynaptic stretch reflex
2. Polysynaptic withdrawal reflect (touch a pin or something hot)
What are the 3 neuronal circuits?
- Diverging
- Converging
- Reverberating
What is the diverging circuits?
much larger response. Each one of the axons have branches that stimulate at least two other neurons. ex: stretch reflex
What is the converging circuit?
take information from a bunch of different places and integrate that into a single input. Ex: see someone walking towards you = 3 signals: 1) memory yes I like the person, 2) see them walking, 3) hear them yelling your name. One output = you stop and talk to them
What id the reverberating circuit?
for rhythmic activities. input from a single neuron that gives you output but goes in a loop until something stops the input at the origin. Ex: arms swinging while walking
What are the two types of neural processing?
- Serial
2. Parallel
How is serial different from parallel processing?
- Serial
- neurons that synapse in a one-on-one sequence of a signal pathway, ex: reflex arc - Parallel
- info from a single neuron is sent along two or more parallel pathways multiple signals are integrated
A nerve is a
bundle of neurons containing multiple axons
Neuron is a
single cell
