PERCEPTION AND COORDINATION

NERVOUS SYSTEM ANATOMY & PHYSIOLOGY

Functions

• receives information
• communicates information
• processes information
• transmits information

Neurons - basic unit of the nervous system

• Cell Body (soma) - primary component of the grey matter of the CNS
• Cell Membrane - encloses outer boundary of soma; receives multiple synapses
• Axon - transmits information away from the soma
• Dendrites - conduct impulses toward the soma
• Myelin Sheath - insulator of axons and makes up the white matter of the CNS
• Synapse - specialized site where neurons make functional contact with each other

Characteristics of Neurons

• Irritability/Excitability - ability of the neuron to respond to stimulus
• Conductivity - ability to transmit nerve impulses to effector organs

resting potential --> depolarization (sodium ions rush into soma) --> action potential (a nerve impulse is generated and transmitted) --> repolarization (potassium ions rush out of cell; no other impulses can be made) --> ion concentration is restored by sodium potassium pump

CLUE: PISO (Potassium Inside, Sodium Outside) --> applicable to all cells

Cerebrum Parts and Functions

• Frontal Lobe - smell, thinking, abstraction, conceptualization
• Parietal Lobe - taste, perception, interpretation, recognition of body parts
• Temporal Lobe - hearing, memory
• Occipital Lobe - sight, understanding written material
• Broca's Area - language expression
• Wernicke's Area - language comprehension

CLUE: brOca --> O for Out, language going OUT of the brain or being expressed

CLUE: wernIcke --> I for In, language going IN the brain or being understood/comprehended

Diencephalon Parts and Functions

• Thalamus - relay station of impulses; sends and receives all sensory impulses
• Epithalamus - sleep wake cycle
• Subthalamus - pathway for efferent impulses from the brain
• Hypothalamus - temperature regulation, hormones, fluid & electrolyte regulation

Brainstem Parts and Functions

• Midbrain - reflex center, pathway for efferent impulses
• Pons - rhythm of breathing; from inspiration to expiration and again
• Medulla - swallowing, cardiac & respiratory control
• Cerebellum - orientation to time and space, voluntary movements
  

PERCEPTION AND COORDINATION

Perception - awareness of stimuli from the environment through the senses

Coordination

• occurs in the CEREBELLUM
• process of synchronizing or integrating contraction of muscles in relation to each other for movement
• harmonizing the functioning of parts for a response

Sight

• sensory cells: RODS (black) AND CONES (color)

light enters cornea --> aqueous humor --> lens --> vitreous humor --> retina --> rods and cones --> axons of optic nerve --> impulses carried by nerve fibers --> at optic chiasm, fibers cross over to opposite side (decussation) --> nerve fibers are now called optic tracts --> optic tracts connect to the thalamus --> axons form the optic radiation which run all the way to the occipital lobe --> visual interpretation

Taste

• sensory cells: TASTE BUDS

food and saliva mix --> chemicals in food dissolve in saliva --> chemicals touch the tongue's papillae --> taste buds --> gustatory cells transmit impulses via facial, glossopharyngeal, and vagus nerves --> impulses run toward medulla oblongata --> fibers connect to thalamus and connect to parietal lobe --> taste interpretation

Smell

• sensory cells: OLFACTORY HAIRS

air enters nose --> chemicals in air touch olfactory hairs --> nasal epithelium --> olfactory bulb --> olfactory tract --> olfactory nerve --> impulses run toward hypothalamus --> fibers connect to frontal lobe --> smell interpretation

Hearing

• sensory cells: HAIR CELLS

sound waves enter ears --> external auditory canal --> tympanic membrane (eardrum) vibrates --> vibrations travel to ossicles and oval window --> vibrations pass the basillar membrane and on to the round window --> hair cells move in relation to vibration in the cochlea at the Organ of Corti --> impulses travel via the vestibulocochlear nerve --> impulses pass through thalamus and transmitted to temporal lobes --> sound interpretation

Touch

• sensory cells:
• thermoreceptors - heat and cold
• nociceptors - pain
• free nerve endings - touch, pressure, stretch
• Meissner's corpuscle - changes in texture, slow vibrations
• Pacinian corpuscle - rapid vibrations
• hair end organ - initial touch, movement changes in hair
• Ruffini's end organ - tension deep in skin
• Merkel's disc - sustained touch and pressure

stimulus on skin --> cutaneous receptors receive stimuli --> impulses generated --> impulses travel along ascending tract up to the CNS --> impulses pass through the medulla then through the thalamus --> impulses sent to the somatosensory cortex at the topmost area of the parietal lobe