Responding to the environment Flashcards
What are co-ordinating systems
system allows communication between the receptors and effectors of the body so that correct reactions can be brought about
the nervous co-or. system responds fastest and is brought about by impulses traveling along nerves
what are the functions of the nervous and endocrine co-ordinating systems
work together to respond to environmental changes and control conditions inside the body
What is the nervous system responsible for
it is the bodies control and communication centre
providing continuous flow of info.
it enables the body to function in an orderly way
how does the nervous system function
Sensory function- sensory receptors detect change in the external and internal environment
Integrative function- central nervous system receives this info. and identifies which effectors need to react to stimulus
motor function - effectors (muscles and glands) respond appropriately
[stimuli are physical or chemical changes in the environment, capable causing response in an organism]
What is the Central Nervous System responsible for [3]
brain and spinal cord
1 processing all information coming from senses
2 keeping our organs and reflexes functioning
3 directing movements, thoughts and feelings
How is the CNS protected and nourished
by three connective tissue membranes ( meninges )
- space between the second and third layer has cerebro-spinal fluid acting as a cushion against shock/damage
as well as a bony case made up of two separate structures
- Cranium for mechanical injuries + made up of 8 curved skull bones placed firmly together by sutures
- Vertebral column made up of 33 irregular shape vertebrae around spinal cord
What is the purpose of cartilaginous discs, joints and the S-shaped spinal cord
prevents jarring of the CNS by giving the body spring and resilience
what holds the two cerebral hemispheres of the cerebrum together
between the longitudinal fissure is a mass of myelinated nerve fires - Corpus callosum
what is the function of the corpus callosum
provides for communication between cerebral cortex and lower parts of the CNS enabling them to function as a whole
why is the cerebrum folded and grooved
enlarges the surface are so large amounts of brain cells can fit in the cranial cavity
deeper folds divide the brain into 4 lobes
grooves- sulci
folds- gyri
what are the cavities within the brain called and what are they filled with
ventricles and cerebro-spinal fluid
Where is the cerebral cortex located and what is it made up of
outer 3mm of the cerebrum
made up of a collection of cell bodies neurons (grey matter)
below the grey matter is white matter (myelinated nerve fibres)
List 3 functions of the cerebrum
- motor area
- frontal lobe where voluntary movements of body originate - sensory area
- receive and interpret impulses from sense organs [hearing, tasting, skin sensations and sight] - association cortex
- higher mental activities [intelligence, language and consciousness]
Describe the location and structure of the cerebellum
location- behind and below cerebrum
made up of two hemispheres
white matter looks like branches with grey matter surrounding it = where ‘tree of life’ name came from
What are the 3 functions of the cerebellum
- co-ordinate the actions of voluntary muscles= smooth and controlled physical actions
- muscle tone
- posture and balance by using info. from inner ear
Describe the structure of medulla oblongata
forms the lowest part of the brain stem and passes through the foramen magnum (big hole) at base of the cranium for the spinal cord.
State 3 functions of the medulla oblongata
- pathway for impulses between brain and body
- reflex centre [breathing, heart beat, blood pressure and swallowing + peristalsis]
- controls less important reflexes e.g. sneezing
What is the spinal cord
an elongated rod of nervous tissue extending from the medulla oblongata through the foramen magnum + situated in vertebral canal of vertebral column
[ 45cm long]
Briefly describe the structure of the spinal cord
- has an H-shaped central area of grey matter [nerve cell bodies, dendrites and synapses]
- white matter surrounds this [made of axons and myelin sheaths]
- central canal runs down from ventricles of brain and holds the cerebro-spinal fluid [ is in the centre of the grey matter]
- pair of spinal nerves enter and leave the cord between successive vertebrae (31 pairs)spinal nerves have dorsal roots which enter the grey matter and ventral roots leaving it
- dorsal root has collection of neuron cell bodies [ganglion]
name two functions of the spinal cord
- pathway for impulses
- seat of primitive reflex actions [ spinal reflexes to protect body e.g. knee jerk reflex] therefor it has an integrative function
What is the PNS
all the nervous tissue outside the CNS
linking CNS to receptors and effectors of body
(43 pairs)
12 cranial nerves = sensory and motor nerves [afferent and efferent]
and 31 pairs spinal nerves
What are the 2 functions of the PNS
- Sensory function by collecting info. from receptors via impulses along afferent neurons to CNS
- Motor function by transmitting impulses from CNS to effectors via efferent neurons to respond appropriately
How is the motor division of the PNS made up
- Somatic nervous system
2. Autonomic nervous system
State the differences between the somatic [4] and autonomic nervous system [4]
SOMATIC
>motor unit is single neuron
>the cell body of the neuron is in the CNS and the axon
extends to the effector
>no ganglia in motor division
>effectors are voluntary, skeletal muscles
AUTONOMIC
>motor unit is a two chain unit
>cell body of first motor neuron is in the CNS and its axon synapses with the second neuron in a ganglion outside the CNS
>postganglionic axon extend to effector
>effectors are smooth, involuntary muscle, cardiac
muscle and glands
What is the Autonomic nervous system made up of
The parasympathetic and sympathetic nervous system
State the structural differences between the parasympathetic and sympathetic nervous system
PARASYMPATHETIC
- motor neuron leaves CNS from brain and sacral region of spinal cord
- ganglia are in wall of effector ( pre-ganglionic fibres long and post-ganglionic fibres short)
SYMPATHETIC
- motor neurons leave CNS from thoracic and lumbar regions of spinal cord
- ganglia close to spinal cord [pre- gang fibres short and post-gang fibres long]
What is the function of the sympathetic nervous system
works together with adrenalin in emergency situations causing stress requiring fight or flight
stimulation by these nerves = more oxygen, glucose and blood sent to skeletal muscles for cellular respiration to release more energy for action
What is the function of the parasympathetic nervous system
enables body to rest and recover from sympathetic stimulation until back to normal state
What is double innervation
most organs are innervated by sympathetic and parasympathetic fibres
What is the name of the opposing effects of the para and sympathetic nervous system
effects are antagonistic
