Ch 8 Flashcards
What does the rental nervous system consist of?
Brain and spinal cord
What does the brain and spinal cord do? (CNS)
Brain-located within the cranium
Spinal cord- located within the spinal column from the brain to the lumbar vertebrae
It integrates and coordinates the processing of sensory data and the transmission of motor commands.
What is the peripheral NS?
Includes all the neural tissue outside the CNS
Consists of two divisions, the afferent(afferens, bringing to) division from the receptors.
The efferent division carries motor commands from the CNS to muscle and glands. Includes the autonomic NS and somatic NS
What does the peripheral NS do?
The autonomic NS control system the acts largely unconsciously and regulates bodily functions such as the HR, digestion, Respiratory rate, pupillary response, urination, and sexual arousal.
What two types of cells are in near tissue?
Neurons and neuroglia
What are neurons?
Neurons are the basic functional units of the nervous system. All neural functions involve the communication of neurons with one another and with other cells.
What is the structure of neurons?
Multipolar neurons are the most common type.
A MP neuron has a cell body, several branching, sensitive dendrites which receive incoming signals, and a single long axon, which carries outgoing signals toward one or more axon terminals.
What is the neuroglia cells in neural tissue?
Regulate the environment around neurons, provide a supporting framework for neural tissue, and act as phagocytes. Far outnumber neurons.
What are clusters of rough endoplasmic reticulum and free ribosomes?
They are known as nissl bodies. They give a gray color to areas containing neon cella bodies and account for the color of gray matter seen in brain and spinal cord dissections.
What is another name for electrical impulses?
Action potential that travels along the axon.
Where does action potentials begin?
At a thickened region of the cell body called the axon hillock. the axon may branch along its length, producing branches called collaterals.
What is a synapse?
A site where a neuron communicates with another cell.
What are dendrites?
Dendrites are processes (extensions) that transmit impulses toward the cell body
What of a neuron transmits impulses away from the cell body?
The one axon of a neuron
In the Peripheral NS, what type of cells are axons and dendrites wrapped in?
Schwann cells
What are schwann cells?
Schwann cells grow to surround the axons and dendrites, enclosing them in several layers of schwann cell membrane.
These layers are the myelin sheath; myelin is a phospholipid that electrically insulates neurons.
What is the neurolemma?
Wherever a Schwann cell covers an axon, the outer surface of the schwann cell is called the neurilemma.
The nuclei and cytoplasm of the schwann cells are outside the myelin sheath and are called the neurolemma.
There are NO SCHWANN CELLS in the CNS, so regeneration of neurons is not possible
What are the nodes of ranvier?
The spaces between adjacent schwann cells
Important for conduction
What is an action potential (electrical impulse)?
Propogated change in the membrane potential of excitable cells.
Excitable cells are the only cells that have an electrically excitable membrane tat can be stimulated to propagate action potentials.
Muscle fibers, cardiac muscle cells, and the axons of neurons have excitable membranes.
An action potential in a neuron is also known as a nerve impulse.
what is a synapse?
A Synapse is a site where a neuron communicates with another cell.
In the NS, info moves from one location to another in the form of action potential (nerve impulses) along axons.
Consequence of the presence of synapses is that they ensure one-way transmission of impulses
Where does a neuron communicate with a muscle cell?
Neuromuscular junction.
What are neurotransmitters and an example?
Convert electrical signals to chemical messages at the synapse (where a neuron communicates with another cell)
EX: acetylcholine
What are the types of sensory neurons?
Sensory neurons: carry info from the body to the brain
Somatic sensory neurons- from receptors in skin, skeletal muscles, and joints are called somatic sensory neuron.
Visceral sensory neurons- from receptors in internal organs
What are the type of motor neurons?
Motor neurons: carry info from the brain and spinal cord to effectors
Somatic motor neurons: linked to skeletal muscle
Visceral motor neurons: linked to glands
Types of neurons
Interneurons- found entirely within the CNS
Connect neuron to neurons
What is a nerve?
A nerve is a group of axons of many neurons, with blood vessels and connective tissue.
How many cranial nerves are there?
12 pairs
