the nervous system Flashcards
what are the functions of the nervous system?
- collect information: monitor external and internal changes (sensory input from PNS)
- process and evaluate information: processes sensory input and determines response
- response to information: dictates response by activating effector organs
what makes up the nervous system?
neural tissues (neurons + glial cells)
what is the sensory nervous system?
- contains receptors
- transmits information from receptors to CNS
what is the motor nervous system?
- transfers information from the CNS to the rest of the body
- sends motor information to effectors
what is the somatic sensory system?
- receives sensory information from skin, fascia, joints, skeletal muscles, and special senses
- free nerve endings in almost every body tissue
- includes receptors for touch, pain, pressure, vibration, and temperature
- also has proprioception (sense of body in space) in skin, body wall, and limbs
what is the visceral sensory system?
- sensations from the organs (digestive and urinary tracts, reproductive organs, etc.)
- only senses stretch and temperature
what is the somatic motor system?
- “voluntary nervous system”
- innervates skeletal muscles
- AKA voluntary nervous system
what is the autonomic motor system?
- “involuntary” nervous system
- innervates cardiac + smooth muscles, and glands
- have no control
- subdivides into the sympathetic and parasympathetic systems
what is nervous tissue?
- 2 types of cells: neurons + glia
- neurons transmit electrical signals (excitable)
- glia “nerve glue” are supporting cells (not excitable)
describe the structure of a neuron
- dendrites: receive signals, transmits to cell body. dendrites are smaller projections from the soma
- soma (cell body): contains nucleus, cytoplasm, orgnalles
- axon (long cell process): transmits signal to axon terminals (note direction of signal movement)
- myelin sheath insulates axon, helps propogate signal
what role to dendrites and axons?
signal pathway:
dendrite —> cell body —> axon —> axon terminal (end of axon)
the more dendrites a neuron has, the more impulses a neuron can receive from other neurons
what is a synapse?
- the site where an axon connects with another cell (eith neuron, muscle, or gland cell)
- 2 types:
+ chemical synapse (most numerous, use neurotransmitters)
+ electrical synapse rely on flow of ions at gap junctions
what are the 4 types of CNS glia?
- ependymal cells: helps produce CSF
- microglia: defense
- oligodendrocytes: mylienates axons
- astrocytes: most common, blood-brain barrier
what is a nerve?
- defined as a collection of axon in the PNS
- the axons are arranged in parallel and wrapped in connective tissue
- a nerve can contain myelinated and/or non-myelinated, and sensory and/or motor axons
what is the structure of a nerve?
- each axon is surrounded by myelin sheath (schwann cells)
- groups of axons are nerve fasicles
- groups of fasicles = nerves
what is the endoneurium?
sheath that surrounds the axon and myelin sheath
what is the perinium?
sheath that surrounds the fasicle
what is the epineurium?
sheath that surrounds the entire nerve
satellite cells
found in ganglia, surround the neuron’s cell bodies
what are schwann cells?
sheath myelinated axons of the PNS
what are ganglia?
collections of neuron cell bodies outside of CNS
what is multiple sclerosis?
progressive demyelination of neurons in CNS with destruction of oligodendrocytes. interrupts conduction of nerve impulses. inflammation leads to scarring and permanent problems
