model 4 Flashcards
what does the brain do
The brain:
- receives, localises and interprets sensory input
- generates the motor output that controlled the activities of muscles and glands.
responsible for emotions, behaviour, personality and memories.
Composed of interneurons and neuroglia
Requires constant supply of oxygen and glucose
what happens to the brain if deprivation of blood fro just a few minutes
irreversible damage
what gray matter contain in the brain
- neuroglia
- cell bodies of interneurons and their dendrites (organised into nuclei)
whats white matter contain in the brain
- neuroglia
- myelinated axons of interneurons (organised into tracts)
whats the three types of tracts in white matter in the brain
commissural tracts: conduct information between the two cerebral hemisphere eg. Corpus callous
Association tracts: conduct information between cortical areas in the same hemisphere
Projection tracts: conduct information between the cerebral cortex and lower parts of the CNS, eg thalamius, Brian stem and spinal cord.
whats the cerebrum
largest part of the brain
whats the structure of the cerebrum
divided along the midline into two cereal hemispheres by the longitudinal fissure (fissure=deep groove)
Separated from the cerebellum by the transverse fissure.
Surface is convoluted
gyrus/gyri=ridges and sulcus/sulci=shallow groove OVERAL increases the surface area of the cerebellum = more neutrons
whats the four lobes of the cerebrum
frontal, parietal, temporal, occipital and insula
whats the three regions of the cerebral hemisphere
Cerebral cortex- outer region of gray matter (contains Nuclei)
Cerebral white matter- inner region of white mater (contains tracts)
Basal nuclei- islands of grey matter deep within the white matter (contains cell bodies of interneurons)
whats the cerebral cortex(outer grey matter) function
- receives, localises and interprets sensory input
controls voluntary skeletal muscle movements
Performs intellectual and language functions
Stores and processes memories
Responsible for our emotions, behaviour and personality
whats the three main functional areas of the cerebral cortex
motor areas
sensory areas
association areas
what are the motor areas of the frontal cerebral cortex
located in the frontal lobe of each cerebral hemisphere. Brocas, frontal eye field, premotor cortex, primary motor cortex and central sulcus all involved.
wheres the primary motor cortex located
in precentral gyrus of each frontal lobe
what does the primary motor cortex function
generates the somatic motor output that stimulates voluntary skeletal muscle movements.
More region located for hands because of complex nature of its movement.
damage to primary motor cortex leads to
paralysis, loss of voluntary movements.
whats the function of motor association area
plan and coordinated voluntary motor activities
Act via the primary motor context
what does the frontal eye field do
controls voluntary eye movement
function of borocas area
controls muscles involved in speed production, usually located in the left hemisphere only,
damage to broca areas
boraca aphasia= difficulty producing words
function of premotor cortex
controls learned, skilled motor activities of a complex nature eg typing, tying a bow.
damage to premotor cortex
=loss of complex motor skills, individual movements unaffected.
location of sensory areas of the cerebral cortex
in the insulua, parietal, temporal and occipital lobes
function of sensory areas
Allows us to becomes consciously aware of sensation originating form:
General sensory receptors for pain, temperature, touch, vibration, pressure, proprioception
Special sensory receptors for vision, smell, taste, hearing and balance.
location of primary somatosensory cortex
in the post central gyrus of each parietal lobe (behind central sulcus)
function of primary somatosensory cortex
Perceives sensations of touch, pain, vibration, pressure, temperature and proprioception.
Locates the origin of the stimulus (sensory input)
Specific areas receive sensory input from a specific part of the body.
A greater number of receptors means more sensory input therefore a greater number of cortex
Face, tongue, hands larger about of context because larger amount of sensation.
location of somatosensory association area
behind and receives general sensory input from, the primary somatosensory cortex
function of somatosensory association area
- interprets incoming general sensory input and compares it to store memories of past sensory experiences so that you can recognise an object by touch alone
- for example able to known things you feel without seeing them eg phone or keys in handbag
damage to somatosensory association area
=lose the ability to identify objects by touch alone. Would have to pick up keys, look at it to know its keys.
location of visual areas
occipital lobes
function of visual cortex
Reciecives visual input detecte by photoreceptors
damage to visual cortex
functional blindness
visual association area function
Interprets visual input, allows us to recognise what we see
Stores memories of past visual images
damage to visual association area
failure to recognise objects eg looking at a drink bottle and not knowing its a drink bottle
location auditory areas
each temporal lobe
function auditory cortex
Receives sound input detached by their cell receptors in the ear to produce and locate sounds
damage of auditory cortex
deafness
auditory association area function
Interprets auditory input, allows us to recognise spoken words and sounds eg scream, music
Stores memories of past sounds
damage to auditory association area
failure to recognise what is hear.
location and function of olfactory cortex
located in temporal lobe
Perceives different odours
location and function of gustatory cortex
located in the insult
Perceives taste sensations
location and function of visceral cortex
located insula
Perceives visceral sensations
Eg upset stomach
location and function of vestibular (equilibrium) cortex
located in Insula
Awareness of balance
location of wernickes area
located in left temperal lobe only
function of wernickes area
Involves in language comprehension, allows us to understand written and spoken language
damage of wernickes area
inability to comprehend written or spoken language
location and function of prefrontal cortex
located in frontal lobe
Responsible for intelligence, personality and behaviour
damage of prefrontal cortex
personality disorders
cerebral basal nuclei function
-islands of grey matter
communicate with motor areas of cerebral cortex to ensure smooth skeletal muscle movements
Helps start, stop and monitory intensity of skeletal muscle activities to facilitate smooth movement.
Regulated by neurotransmitter dopamines
loss of dopamine in cerebral basal nuclei
parkinsons disease
movements over controlled
structure of cerebellum
second largest part of the brain
Convoluted surface
Divided into two symmetrical hemispheres
Each hemisphere is subdivided into an anterior and posterior lobe and contains:
An outer context of grey matter “cerebellar cortex”
An inner white matter “arbor vitae”(means tree of life because it resembles branches of a tree)
function of cerebellum
Ensures smooth, coordinated skeletal muscle movements, and maintains posture and balance.
Receives visual, balance and proprioceptive informality and uses this information to adjust:
Motor activities of the cerebral cortex
Muscle tone to maintain posture and balance
damage to cerebellum
caused by a head injury, stroke, drugs eg. Alcohol
=loss of balance and uncoordinated movements (ataxia)
A tendency to fall, jerky and inaccurate movements, wide unsteady walking gate, slurred speech and abnormal eye movements.
whats the diencephalon include
the thalmus, hypothalamus and epithalamus.
function of thalamus
relay station for information coming into the cerebral cortex (entrance to cerebral cortex)
Sorts, groups and priorities incoming sensory input
Relays sensory input to the correct cerebral destination eg taste information to the gustatory cortex
Relays the ‘motor adjustments’ made by the basal nuclei and cerebellum to the motor areas of the cerebral cortex.
Involved in cortical arousal(alertness), emotion and memory
part of limbic and reticular formation
location of hypothalamus
small structure below the thalamus
function of hypothalamus
controls the autonomic nervous system
regulates the activities of autonomic centres in the brain stem and spinal cord, e.g. cardiovascular, respiratory and gastrointestinal centres
centre for emotional responses, e.g. fear, rage, pain, pleasure - part of the limbic system
Regulated body temperature (alerts blood flow and sweat gland activity)
Regulates water and food intake (stimulates hunger, satiety and thirst
Regulates sleep wake cycle
Produces hormones; ADH, oxytocin and regulatory hormones that control secretion of the pituitary hormones (part of endocrine system)
location of epithalamus
- most posterior proportion of the diencephalon
function of epithalamus
Produces melatonin
Helps hypothalamus regulate the sleep wake cycle
structure limbic system
specifics areas of the cerebrum (prefrontal cortex, amygdala and hippocampus), hypothalamus and thalamic nuclei.
Axons tracts that links regions together eg fornix connects hippocampus to hypothalamus
function of limbic system
allows us to be consciously aware and control emotions
Allows us recognise emotions, express and react to emotionally to events
Links odour to emotions and memories
Involved in the formation and storage of long term memories
structure of brain stem
-3 parts; mid brain, pons and medulla oblongata. Reticular formation (throughout)
mid brain contains and function
contains gray matter
visual and auditory reflex centres eg. Sudden unexpected light or sound
Substantia niagria
Cranial nerve nuclei that control eye movements
pons contains and function
gray matter contains:
Cranial nerve nuclei involved with taste, chewing, eye movements, hearing, balance and facial expressions via cranial nerve 5-8 (V-VIII)
Nuclei regulates breathing
medulla oblongata contains and function
autonomic nuclei controlled by hypothalamus
**Cardiovascular center:
Cardioaacceleratory centre
Cardioinhibitory centre
Vasomotor center-
***Respiratory centres
Control the rate and depth breathing
Nuclei involved I reflexive actions such as vomiting, coughing, hiccuping and sneezing
Cranial nerve involved in swallowing, tongue movements and digestive functions via (IX, X and XII)
what does the involves
Cardioaacceleratory centre
Cardioinhibitory centre
Vasomotor center-
Cardioaacceleratory centre- increases heart rate and force of contraction
Cardioinhibitory centre- decreases heart rate
Vasomotor center- adjusts blood vessel diameter
function of reticular formation
functional systems that events through central core of brain stem ands connections with many areas
Acts as sensory filter, filters out unimportant things eg. Feeling of clothes etc.
Contains the reticular activating system, maintains cortical alertness (consciousness), inhibited by hypothalamic sleep centres(alcohol or sleeping pills)
damage of reticular formation
coma
major artier to the brain
Right and left internal carotid arteries (front of neck)
right and left vertebral arteries (back of neck) take blood to the brain.
6 types of cerebral artier supply blood to cerebrum
anterior cerebral arteries-supply blood to the frontal & parietal (medial areas)
middle cerebral arteries-supply blood to frontal, parietal & temporal lobes (lateral areas)
posterior cerebral arteries-supply blood to temporal lobes (inferior areas) & occipital lobes
whats does veretbral areties fuse to form
basil artery which divides into left and right posterior cerebral arteries.
whats the cerebral arterial circle
connecting blood vessel at the base of the brain. - anterior communicating artery: connect two anterior cerebral arteries
posterior communicating arteries: connecting posterior cerebral and internal carotid arteries.
function of cerebral arterial circle
-connects anterior blood supply (left to ride side)
connects Brians anterior and posterior blood supplies (back to front)
Equalises blood pressure in the brain, makes sure the entire cerebral gets blood flow constantly.
whats venous drainage
venous blood(deoxygenated blood) drains into dural sinuses Converage at the back of the skull to form the sigmoid sinus From sigmoid sinus venous blood flows into internal jugular views, to superior vena cava to heart.
causes for a stroke
blood clot in a cerebral artery= ischameic stroke (most common)
Ruptured blood vessels= hemorrhagic stroke
symptoms for a stroke
headache, paralysis (usually face and arm), loss of vision/ blurred vision, difficulty speaking and understanding speech.
Symptoms last more than 24 hours - life.
whats a transiet ischaemic attack TIA
a mini stroke
causes of a TIA
blood flow to brain area is temporarily reduced or blocked- no neutrons die.
symptoms of TIA
lasts less than 24 hours
Warning of impending stroke between 3 months to 5 years
whats alzheimers disease
progressive degenerative disease of the brain
causes for alzheimers disease
death of neurons causes brain to shrink
Particularly affects hippocampus and prefrontal cortex
Senile plaques: toxic deposits of beta amyloid Pepside from between neutrons
Tanglers- twisters fibers that interfere with transporting mechanisms within neutrons
symptoms of alzihemers disease
Memory loss, shortened attention span, disorientation, language difficulties and personality changes.
what is parkinsons disease
progressive degenerative disease of the Brian
Degeneration of dopamine
causes of Parkinson disease
unknown
symptoms of Parkinson disease
- persistent tremors at rest, suffering gait difficulty swallowing and stiff facial expressions.
whats the meninges
-three consecutive tissue membranes that surround and protect the brain and spinal cord from mechanical forces.
whats the three layers of matter in the Brian
dura matter
arachnoid matter
pia matter
whats the dura matter
outer most membrane
strongest and toughest of the three membranes
Attach to inner surface of the skull (periosteal layer) and covers external surface of the brain (meningeal layer).
Dural sinuses in the membrane all venous blood from the brain and direct it into jugular veins of the neck.
whats the arachnoid mater
middle membrane
whats the pia matter
inner most membrane
whats cerebrospinal fluid (CFS)
clear colourless liquid that surrounds and bathes the brain and spinal cord
function of cerebrospinal fluid (CFS)
a shock absorb medium to protect the brain from mechanical forces and floats the brain within the cranial cavity.
Therefore reduceng weight of the brain by 97% and prevents lower prt of the brain being crushed by weight.
Acts as a diffusion medium for exchange of nutrients waste products between blood and neural tissue.
where is cerebrospinal fluid produced
within the ventricles by a structure called choroid plexus.
Choroid plexus surrounded by ependymal cells
These cells allow selected substances to be filtered from the blood plasma to produce CFS.
steps of cerebrospinal fluid after produced by chord plexus
Move through the ventricles
Enters subarachnoid space of the meninges and central canal of the spinal
flows through the subarachnoid space and central canal
is absorbed into the dural sinuses via the arachnoid villi.
whats hydrocephalus
If the normal circulation or absorption of CFS is obstructed (by a tumor, brain heamorrhage, inflammation) then CF accumulated within and builds pressure on the brain. Condition known as Hydrocephalus or “water on the brain”
hydocephalus babies vs adults
okay in newborns as it just causes the head to enlarge as bones of the skull have not fused yet.
In adults condition is life threatening, the brain will eventually crush and damage delicate neural tissue of the brain and compress blood vessels reducing blood flow.
symptoms of hydrocephalus
sleepiness, neural dysfunction, or stroke due to impaired blood flow.
what occurs if excess fluid not removed wiht hydrocephalus
not removed eventually brain stem through the large foramagnum known as coning. ALWAYS RESULTS IN DEATH.
treatment for hydrocephalus
inserting a shunt into ventricles to drain the excess fluid into a vein in the neck or abdominal cavity.
whats the blood barrier and its function
protects internal threats such as pathogens to the neural tissue of the brain.
It is a selective barrier; permeable to lipid-soluble compounds such as oxygen, co2, lipids and alcohol, permeable to nutrients such as glues and essential amino acids and impermeable to wastes, proteins, toxins, drugs and antibiotics.
places in the brain that does not have a blood barrier
pineal gland: secret hormones in to blood circulation
Posterior lobe
Vomiting centre of medulla oblongata: blood from poisonous substances and initialises vomiting to remove toxic substance
Hypothalamus: regulate body temperature and sample chemical composition of the blood.
space between the arachnoid matter and pia matter
subarachnoidspace
