Chapter 12 Flashcards
3 steps for nervous system function
- input
- processing
- output
input
conduction of signals from sensory receptors to processing centers
Processing
- what does it include
- definition
- brain and spinal cord
- interprets these sensory signals and forms a response
output
conduction of signals to an effector (away from brain and spinal cord)
2 main divisions of the nervous system
- central nervous system
2. Peripheral nervous system
central nervous system
-what does it include
brain and spinal cord
peripheral nervous system
- what does it include
- 2 branches
- cranial nerves and spinal nerves
- somatic nervous system and autonomic nervous system
somatic nervous system
- voluntary or involuntary?
- ex
- voluntary
- skeletal muscles
autonomic nervous system
- voluntary or involuntary?
- 3 ex
- involuntary
- smooth, cardiac muscle and glands
2 divisions of autonomic system
- sympathetic (fight and flight)
2. parasympathetic (rest and digest)
2 types of cells
- Neurons
2. neuroglia
neurons
conduct electrical signals or action potentials/impulses
neuroglia
- how much percent of the nervous system
- 4 functions
- 90%
- supports cells
- provides framework for nervous tissue
- protection
- controls composition of extracellular fluid
- supports cells
extracellular fluid
cerebrospinal fluid in CNS (CSF)
Ependymal cells
Assists with producing, monitoring, and circulation of CSF
Microglia cells
Engulfs cellular debris, waste and pathogens
Oligodendrocyte
- myelinates CNS axons
- structural support
Astrocyte
-2 functions
- maintenance of blood/brain barrier
2. structural support
3 properties of a neuron
- generally amitotic (cannot be replaced)
- extreme longevity
- high metabolic rate (many mitochondria)
5 parts of a neuron
- dendrites
- cell body
- axon hillock
- axon
- telodendria
dendrites
- how many branches
- function
- 6
- receives signals
cell body
- known as
- contains 4 things
- lacks
- abundant in
- perikaryon
- soma
- nucleus, golgi, mito, RER
- centrioles
- abundant in cytoskeleton components: neurofibrils
- cytoplasm surrounding nucleus
axon hillock
initial segment between cell body and axon
axon
- function
- 2 types
- carries signals (action potentials) away from cell body
- Naked-unmyelinated
- Myelinated - covered with myelin sheath
- Naked-unmyelinated
Telodendria
contains axon terminals =synaptic knobs
myelin sheath
- formed by (general)
- cells that form myelin sheath
- how do they form it
- 2 functions
- neuroglia
- oligodendrocytes (CNS) and Schwann cells (PNS)
- by wrapping their cytoplasm and membranes around the axon
- protection
- increases speed of action potential conduction (bc myelin is an insulating material)
- protection
4 steps to forming a myelin sheath
- neurolemmocyte starts to wrap around a portion of an axon
- Neurolemmocyte cytoplasm and plasma membrane form consecutive layers around axon
- the overlapping inner layers of the plasma membrane form the myelin sheath
- the neurolemmocyte cytoplasm and nucleus are pushed to the periphery of the cell as the myelin sheath is formed
Nodes of Ranvier
- what is it
- what happens
- naked axon
- action potentials are conducted from node to node =saltatory conduction
saltatory conduction
very fast and efficient way to carry action potential down axon
3 structural classifications
- bipolar
- unipolar
- multipolar
bipolar
- what does it look like
- how do action potentials flow
- where is it found
- cell body is located in between the dendrite and axon
- dendrite, cell body, and axon
- rare: generally found in areas associated with special senses
unipolar
- what does it look it
- how do action potentials flow
- common?
- cell body (has an attachment) is located in between dendrite and axon
- dendrites, does not go through cell body, axon
- structure common to most sensory neurons
multipolar
- what does it look like
- how do action potentials flow
- common in?
- cell body is located at the top
- dendrites (attached to soma), soma, axon
- structure of most motor neurons and interneurons
3 functional classifications
- sensory neurons
- motor neurons
- interneurons
sensory neurons (affernet)
carries signals from periphery CNS
motor neurons (efferent)
carries signals from CNS to muscles and glands
interneurons (association)
- most abundant
- carries signals between sensory and motor neurons
