subdivisions of the nervous system Flashcards
central nervous system
- consists of the brain and spinal cord
- processes information from the body and activates appropriate responses
brain
an intricate network of cells that processes information and directs actions within the body
continuously receives/analyses sensory information; responds by controlling all bodily functions and actions
spinal cord
long, thin bundle of nerve tissue that extends from the brain, downwards
injury to spinal cord:
- brain loses sensory input
- leads to paralysis (dependent on severity and where injured)
neural pathway
comprises one or more circuits of interconnected neurons that forms communication networks
some are short and others are long distances; connects brain and body
sensory (afferent) information
received from the body and sends it to the brain
sending information from the body to the brain for processing
motor (efferent) information
received from the brain and sends it to the body
sending information from the brain to the body for action to be taken
peripheral nervous system
- the entire network of nerves outside the CNS
- transmits info to and from the body (sensory and motor functions)
somatic nervous system
- branch of PNS
- connects to sensory organs and skeletal muscles
- controls voluntary movement and sensation
exception: spinal reflexes
skeletal muscles
mucles in SNS, inactive in the absence of motor neuron messages
autonomic nervous system
- branch of PNS
- connects to visceral internal organs and glands
controls involuntary movement
3 branches: sympathetic, parasympathetic and enteric
exception: controlling breathing
visceral muscles
muscles in ANS, have built-in mechanisms to generate and maintain their activity
do not depend on voluntary control by the brain
sympathetic nervous system
- branch of ANS
- activates the visceral muscles in times of stress or threat
- activates the flight-fight-freeze response
- immediately releases adrenaline
- enhances survival (bc immediate response)
parasympathetic nervous system
- branch of ANS
- calms the visceral muscles in times of minimal stress/absence of threat
- maintains internal body environment (homeostasis)
- restores body to state of calm –> reverses bodily changes of SNS
- occurs in the absence of adrenaline
adrenaline does not subside immediately and requires sometime to fully return to PSNS
sympathetic nervous system examples
increased heart rate, breathing, dilated pupils, stopped digestion, perspiration, SAM axis activation
SAM) sympathetic-adreno-medullar
parasympathetic nervous system examples
normal/increased digestion, normal heart rate and breathing, more salivation
enteric nervous system
- branch of PNS
- receives/sends messages to/from PSNS and Symp. NS
nerves lined along the gut (wall of gut, intestines and stomach)
vagus nerve
a nerve fiber that enables direct communication of ENS and CNS (gut-brain axis)
ie stomach sends upward message of fullness and brain sends downward messages of incoming food
conscious response
- controlled by somatic NS
- involves awareness
- one voluntarily acts and responds to sensory stimuli
- intricate responses/ can be learnt
ie the person ‘thinks’, ‘decides’ , ‘interpret’
unconscious response
- person is unaware
- involuntarily, unintentional, automatic
- simple responses/ occurs in the same way each time
- to avoid danger and minimise harm
ie a ‘burning’ mug held; ‘dropping immediately’ on the floor; ‘reacts later’
two types of unconscious responses
- autonomic - regulation of vital body functions (heartbeat, breathing, digestion)
- spinal reflex - when the spinal cord bypasses brain for fast response
spinal reflex
unconscious, involuntary occurring response to certain stimuli without involvement from the brain
- response to potentially dangerous stimuli
spinal reflex steps
- touching hot plate/threat present
- sense organs register information
- sensory neurons carry info to the spinal cord
- interneurons in the SC relay info to motor neurons
- motor neuron carry info away from SC
- muscles receive message to move the hands and fingers
- hand is moved away in a withdrawal reflex
- processing pain in the brain
sensory neurons
- PNS
- incoming info
interneurons
- CNS (spine)
- processing info
