the nervous system Flashcards
central nervous system (CNS)
brain and spinal cord
peripheral nervous system
twelve cranial nerve pairs and 31 spinal nerve pairs
autonomic system
controlling all functions necessary for life
somatic system
all functions that are non-essential for life
sympathetic system
‘fight or flight response’
parasympathetic system
returns the body to normal
general functions of the nervous system
- gather information about internal and external environments
- transmit that information to the CNS
- process that information
- determine a response to that information
- transmit instructions to effector organs
‘fight or flight’ response
a reaction to a potentially dangerous situation. danger does not have to be real to be perceived as such. most of the effects are caused by the release of adrenaline from the adrenal glands.
effects of adrenaline
dilated pupils, decrease in production of slaiva, increased heart rate, dilated bronchioles, inhibits peristalsis, restricts blood flow to digestive system, decreases egestion of digestive enzymes, increases blood flow to muscles, relaxes the bladder valve ans stimulates the conversion of glycogen to glucose.
purpose of adrenaline responses
all of these responses are designed to increase visual acquity, provide sufficient oxygen t increase muscle function and reduce energy wastage and non-essential processes
double innervation
if left uncontrolled, the sympathetic nervous system can result in death. the parasympathetic nervous system is responsible for returning the body to a normal state, reversing all of these effects. this is a negative feedback system.
afferent nerves
moving towards the brain (taking in)
efferent nerves
exiting or leaving the brain
vital reflexes controlled by the medulla oblongata
# Respiratory centre - breathing rate and depth # Vasomotor centre - controls blood pressure and body # Cardio-motor centre - rate of the heart beat # Visceral activities
non-vital reflexes controlled by the medulla oblongata
- salivation
- coughing
- blinking
- hiccoughing
- sneezing
white matter vs grey matter
fat is present in white matter and absent in grey matter. as white and grey matter pass through the medulla oblongata, they switch places.
function of the spinal cord
to connect sensory organs (receptors) to the brain
immediate reflex actions
majority of immediate reflex actions travel to the spinal cord before the brain to increase reflex speed to save time and possibly save your life
effectors
muscles and glands that cause an effect
four main functions of the spinal cord
1 Works with m. oblongata to control reflex actions which are independent of the brain.
2 Afferent impulses are conducted up from receptors via the cord, to the brain.
3 Efferent impulses are conducted are conducted down from the brain, via the cord, to the effector muscles.
4 Sympathetic nerve impulses and some of the para-sympathetic nerve impulses are connected via the spinal nerves to the spinal cord.
sensory neurons
- receive information and conduct impulses from muscles or glands throughout the body to the spinal cord and brain
- afferent neurons
- cell body has only one or two outgrowths - a dendrite and an axon
- monopolar and bipolar neurons
motor neurons
- receive information and conduct impulses from the spinal cord and brain to muscles or glands throughout the body
- Efferent neurons
- Cell body has many outgrowths - dendrites and an axon
- Are multipolar neurons
reflex arc definition
the structure/pathway along which electrical signals travel to generate a reflex action
reflex action definition
a seemingly instantaneous response to any situation that is either life-threatening or potentially harmful
