Nervous System Flashcards
what are coordinating systems
systems that allow communication between the receptors and the effectors of the body so that correct reactions to any change in the environment can be brought about
what two systems work together to respond to changes in the environment and control conditions inside the body
- nervous coordinating system - responds fastest and is brought about by impulses traveling along nerves
- endocrine coordinating system - slower and is brought about by chemicals called hormones which are carried in the blood
what is the nervous system
it is the body’s control and communication centre. it provides a continuous flow of information between the environment, the brain and the different parts of the body. this enables the body to function in an orderly and effective way and to perform all the everyday tasks such as eating, running, solving a problem, controlling emotions such as fear etc.
how does the nervous system function
- sensory function - sensory receptors detect the changes in the external environment and the environment within the organism
- integrative function - the central nervous system receives this information and decides which effectors need to react to the stimulus
- motor function - effectors (muscles and glands) bring about the appropriate responses
what are stimuli
physical or chemical changes in the environment that are capable of causing a response in an organism
gives examples of stimuli in the environment
- light
- temperature
- sounds
- atmospheric pressure
gives examples of stimuli inside our bodies
- blood pressure
- blood pH
- tension in muscles
what is the human nervous system divided into
- Central nervous system
2. Peripheral nervous system
LABEL THE CENTRAL AND PERIPHERAL NERVOUS SYSTEM
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what is the CNS made up of
a concentrated mass of interconnected neurons (nerve cells) grouped together to form
- brain
- spinal cord
what is the CNS responsible for
processing information coming from our senses, keeping our organs and reflexes functioning and directing our movements, thoughts and feelings
how is the CNS protected
- the extremely soft and delicate brain and spinal cord tissue is protected and nourished by three connective tissue membranes called the meninges
- the layer between the 2nd and 3rd layer of the membrane is filled with cerebro-spinal fluid which acts as a cushion, protecting the CNS against shock and damage
- the whole CNS and it’s meninges are enclosed within the bony case made up of two separate structures
- the cranium
- the vertebral column
• other factors such as the S-shaped curvature of the spine, the cartilaginous discs between the vertebrae and joints of the lower limbs all prevents jarring of the CNS
LABEL THE PROTECTIVE LAYERS OF THE CNS
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what is the brain
the enlarged, upper part of the spinal cord, enclosed in a bony cranium
describe the brain (3 points)
- it’s like a mushroom, the cap of the mushroom being the cerebrum snd then stalk being the brain stem
- at the back near the top of the brain stem is a bump, the cerebellum
- the lower part of the brain stem is known as the medulla oblongata
LABEL THE EXTERNAL AND INTERNAL VIEW OF THE BRAIN
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what is the largest part of the brain and what is it divided into and by what
the cerebrum, it is divided into two cerebral hemispheres by a longitudinal fissure
what holds the hemispheres of the brain together
a mass of myelinated nerve fibres, bundled into large tracts that form the corpus (body) callosum (white)
what does the corpus callosum provide for
communication between the cerebral hemispheres and between the cerebral cortex and lower parts of the CNS, which enables them to function as a coordinated whole
what is the surface of the cerebrum made up of
a large number of folds (gyri) and grooves (sulci) that enlarge the surface area so that a large amount of brain cells can fit into a small cranial cavity
what are ventricles in the brain
they’re 4 cavities in the centre of the brain that are filled with cerebro-spinal fluid
what is the cerebral cortex
the outer 3 mm of the cerebrum.
what forms grey matter
the collection of cell bodies of neurons which form the cerebral cortex (the greyness is due to the grey appearance of cytoplasm which is called neuroplasm in neurons)
what makes up white matter
a collection of myelinated nerve fibres (the whiteness is due to the fatty myelin)
what are the functions of the cerebrum
- the motor area (frontal lobe) is where all the voluntary moments of the body originate. we’re able to consciously control our voluntary moments that are brought about by the contraction of muscles
- the sensory areas that receive and interpret impulses from the sense organs. eg.
- heading, tasting, smelling (temporal lobe)
- sight (occipital lobe)
- skin sensations (parietal lobe) - the association cortex is involved with the higher mental activities such as intelligence, memory, perception, language and consciousness. collectively the function of the association areas is to sort out, integrate and store info before it’s sent to the motor areas. eg.
- anger, aggression (frontal lobe)
LABEL THE LOBES OF THE CEREBRUM
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describe the cerebellum
- it lies behind and below the cerebrum
- made up of two hemispheres and has shallow surface folds
- a feature of the cerebellum is the arrangement of the white matter and grey matter. the white matter looks like branches of a tree and is surrounded by grey matter which looks like the foliage - hence the name tree of life
what are the functions of the cerebellum
it receives sensory input from the motor region of the cerebrum, the eyes, muscle spindles and the organs of balance in the ears
- it processes this info and uses it to coordinate the actions of the voluntary muscles so that complicated physical actions can be performed in a smooth controlled way
- it is partly responsible for controlling muscle tone
- using info from the inner ear, it helps to maintain posture and balance
where do we find the hypothalamus
below the thalamus and above the pituitary gland
what are the functions of the hypothalamus
- control the autonomic system and therefore play an important role in maintaining homeostasis by regulating
- body temperature
- water balance and thirst
- food intake
- sleep cycle - it is the centre for emotional response and behavior eg. has nuclei involved in the perception of
- pain, pleasure, fear and rage
- biological rhythms and drives eg. sex drives - it controls the functioning of the pituitary by:
- secreting hormones eg. ADH, which is stored in the posterior lobe of the pituitary
- controlling the release of all the hormones from both lobes and pituitaries
where’s the medulla oblongata
it forms the lowest part of the brain stem and passes through the foramen magnum at the base of the cranium, it is known as the spinal cord
what are the functions of the medulla oblongata
- servers as the pathway for impulses to and from the brain
- it acts as a reflex centre controlling reflexes such as
- breathing
- heart beat
- blood pressure (by regulating vasodilation and vasoconstriction)
- swallowing and peristalsis - it also controls less important reflexes such as sneezing, coughing, hiccuping and salivating
why do the hemispheres of the brain control opposite sides of the body
because nerve fibres between the spinal cord and brain cross over in the medulla oblongata
what is the spinal cord
an elongated rod of nervous tissue that extends from the medulla oblongata through the foramen magnum
how long is the spinal cord
approximately 45 cm