Central Nervous System 1 Flashcards
Structure and Function of Cnetral Nervous System
Consists of:
- spinal cord
- brain
Function is to PROCESS and COORDINATE:
- sensory data
- motor commands
- higher functions of the brain
What actions does the spinal cord facilitate?
- passage of sensory information to the brain
- passage of motor information to the brain
- integrates information and controls spinal reflexes
Spinal Cord: Anatomy
-central canal (cerebrospinal fluid flows through)
-dorsal root ganglia
cell bodies of sensory neurone
-dorsal roots
axons of sensory neurone
-ventral roots
axons of motor neurons
when roots are damaged, the passage of sensory and motor information can be affected
eg. ruptured disk squishing ventral roots may stop person from being able to move
Spinal cord: gray matter
- integrates and initiates commands
- shapes like letter H or butterfly
- cell bodies of neurons
- neuroglia
- unmyelinated axons
- nuclei - functional grouping of cell bodies
Spinal cord: white matter
- forms tracts which carry information into and out of the CNS
- ascending axons carry information to the brain
- descending axons carry information away from the brain
Spinal Nerves
- each side of the spine dorsal and ventral roots join and form a spinal nerve
- spinal nerves are mixed nerves as they contain both afferent (sensory) and efferent (motor) fibres
- each spinal nerve is surrounded by 3 layers of connective tissue
- epineurium
- perineurium
- endoneurium
For a brain to perform all the functions that it must do, it must
- detect and locate the great variety of stimulus types, sources, and happenings in the environment
- make sense of all these sensory events
- respond to all these features by expressing an elaborate behavioural repertoire
- make judgements, learn, and think about all these things
***know regions and their functions
Major Brain regions
Cerebrum Cerebellum Diencephalon -thalamus -hypothalamus -pineal gland -pituitary gland Brain Stem -menencephalon -pons -medulla oblongata
Functions of Cerebrum
- largest part of the brain
- controls all conscious thoughts and intellectual functions
- processes somatic sensory and motor information
- key in processing our general senses: touch, pressure, pain
- conscious thought processes, intellectual functions
- memory storage and processing
- conscious and subconscious regulation of skeletal muscle contractions
Functions of Diencephalon
Relay and processing centers for sensory and motor information
Functions of Hypothalamus
centres controlling emotions, autonomic functions and hormone production
Functions of Mesencphalon (midbrain)
-processes visual and hearing information
superior colliculi - eye tracking
inferior colliculi - hearing
-processing of visual and auditory data
-generation of reflexive somatic motor responses
-maintenance of consciousness
Functions of Pons
-controls breathing
Pneumotaxic area - inhibits inspiration
Apneustic area - stimulates inspiration
-relays sensory information to cerebellum and thalamus
-subconscious somatic and visceral motor centers
Functions of Medulla Oblongata
- cardiovascular centre
- respiratory rhythmicity centres
- relays sensory information to thalamus and other portions of the brain stem
- autonomic centres for regulation of visceral function (cardiovascular, respiratory and digestive system activities)
Functions of Cerebellum
- “cauliflower” appearance
- coordinates contraction of skeletal muscles
- monitors proprioceptive information
- may also serve cognitive function
- coordinates complex somatic motor patterns
- adjusts output of other somatic motor centres in brain and spinal cord
Diencephalon: Thalamus
- filters ascending sensory information to the cerebral cortex
- relays information from cerebellum to the cerebral cortex
- crude recognition of
- pain
- temperature
- pressure
Diencephalon: Hypothalamus
- major regulator of homeostasis
- subconscious control of skeletal muscle
- controls autonomic function
- coordinates nervous and endocrine systems
- regulates body temperature
- circadian rhythms
- emotions and behaviour
Limbic System
Functional Grouping
- establishes emotional states
- links subconscious functions of cerebral cortex with autonomic functions of brain stem
- facilitates memory storage and retrieval
Three functional principles of the Cerebrum
- each cerebral hemisphere receives sensory information from, and sends motor commands to, the opposite side of the body
- the two hemispheres have different functions, although their structures are alike
- correspondence between a specific function and a specific region of cerebral cortex is not precise
Cranial Nerves and Four Classifications
12 pairs connected to the brain
- Sensory nerves: carry somatic sensory information, including touch, pressure, vibration, temperature and pain
- Special sensory nerves: carry sensations such as smell, sight, hearing, balance e.g.. optic nerve
- Motor nerves: axons of somatic motor neurons
- Mixed nerves: mixture of motor and sensory fibres
Spinal cord protection and support
Bones of vertebral Column
Meninges (3 layers)
Cerebrospinal fluid
Brain physical and biochemical protection
Physical protection:
- Cranial bones
- Cranial meninges
- Cerebrospinal fluid
Biochemical protection:
-blood-brain barrier (tight grouping of endothelial cells)
Cerebrospinal Fluid and Functions
- surrounds all exposed surfaces of CNS
- interchanges with interstitial fluid of brain
Functions:
- cushions delicate neural structures (as move head, brain bounces on cranial bones)
- supports brain
- transports nutrients, chemical messengers, and waste products
Blood supply to the brain
- supplies nutrients and oxygen to the brain
- delivered by internal carotid arteries and vertebral arteries
- removed from dural sinuses by internal jugular veins
Clinical Note: Cerebrovascular Disease
- disorders interfere with blood circulation to the brain
- Stroke or Cerebrovascular Accident (CVA)
- shuts off blood to portion of brain, neurone die
Blood-Brain Barrier
- isolates neural tissue from general circulation
- endothelial cells that line cps capillaries are extensively interconnected by tight junctions
- selectively isolates the brain from chemicals that might disrupt neural function
- lipid soluble molecules can diffuse across
- water and ions pass through channels
