The nervous system Flashcards
What are the functions of the nervous system?
- Monitors the internal and external environments
- Integrates sensory info
- coordinates voluntary and involuntary response of organ systems
Name the receptors and what they respond to
Thermoreceptors- change in temp
Mechanoreceptors- mechanical pressure or distortion
Chemoreceptors- chemical change
Photoreceptors- light
What is the CNS?
Central nervous system consisting of the brain and the spinal cord
Its function is to integrate and coordinate sensory data and motor commands
What is the PNS?
All neural tissue outside the CNS
Relays sensory info to the CNS and carries motor commands to the peripheral tissues
What is the afferent division?
The sensory information
What is the efferent division?
The responses
Split into somatic n.s - skeletal muscle contraction and the autonomic ns consisting of parasympathetic and sympathetic
What is the main structure of a multipolar neuron?
Dendrites, cell body (organelles), axon hillock, axon, axon terminal
What is the function of the dendrites?
They are sensitive to sensory stimuli
What are the 4 types of neuron?
Anaxonic, bipolar, unipolar, multipolar
What is an anaxonic neuron?
Mainly found in the brain
small
No anatomic features to distinguish between dendrites from axon
What is a bipolar neuron?
Rare
Special sense organs
1 dendrite and 1 axon with cell body between them
What is a unipolar neuron?
Dendrites and axon are continuous with the cell body off to the side - most sensory neurons in the PNS
What is a multipolar neuron?
2 or more dendrites with 1 axon
Most common in the CNS and all motor neurons in skeletal muscle control
What is the spinal cord and its function?
A major passageway of sensory and motor impulses to and from the brain
It integrates info on its own and control spinal reflexes and automatic responses
What is the difference between a fissure and a sulcus?
They are both grooves but a fissure is deeper
What is grey matter?
Contains cell bodies and neuroglia cells
What is white matter?
Consists of myelinated and unmyelinated neurons
How does the central shape of the spinal cord change as we go down the body?
It decreases
How many segments are in the spinal cord?
31
What is a dermatone?
Each pair of spinal nerves monitor a specific region of the the body surface
What is a dorsal root ganglia?
A bundle of neurons that bring sensory info (afferent) into the spinal cord
What is a ventral root?
Contains axon of motor neurons (efferent)
Does bind with the dorsal to form a spinal nerve
What are horns?
Projections of grey matter
What is the cauda equina?
The sack of nerve roots at the lower end of the lumbar spinal cord
What is the process of the reflex arc?
Arrival of stimulus, receptor, sensory neuron (dorsal root), info processing by CNS, activation of motor neuron (ventral root), effector , response
What do golgi tendon organs do?
Sense tension in the tendon when the muscle contracts
Has an inhibitive afferent neuron
So high forces lead to decrease in muscle activation for protection
What do the muscle spindles do?
Detect rate of change of muscle length
Efferent neuron causes the spindle to contract to maintain tension so if it is stretching rapidly then a vigorous contraction occurs to prevent overstretching
What are the 3 sections of the brain?
Reptilian - stem
Mammalian - limbic system
Higher brain - neocortex - emotional, logic, creativity
What does the brain stem consist of?
Diencephalon
Midbrain
Pons
Medulla oblongata
Cerebellum
What is the dienchepalon?
Consists of the thalamus which relays and processes sensory info and the hypothalamus which centers controlling emotions
What is the mid brain?
Processes visual and auditory data
Maintains consciousness
What is the pons?
Relays sensory info to the cerebellum and thalamus
What is the medulla oblongata?
Relays sensory info to thalamus and autonomic centre for visceral function
What is the cerebullum?
Coordinates complex somatic motor patterns
What is a gyrus?
A ridge on the cerebral cortex
What does the cerebrum consist of?
Frontal lobe- (primary motor cortex- motor response)
Temporal lobe- auditory association area
Occipital lobe- visual association area
Parietal - Primary sensory cortex- receiving and processing sensory info
What are the biochemical protection methods for the brain?
Blood brain barrier
Isolation of CNS from general circulation through variation in permeability of CNS capillaries (astrocytes)
What are the physical protection methods for the brain?
Bones of the cranium
Cranial meninges
Cerebrospinal fluid
Describe the cranial meninges
Layers of connective tissue
Dura mater (Periosteal) then the dural sinus and the dura mater (meningeal layer)
Arachnoid mater
Pia mater - connective tissues between brain and protective layers
Describe the cerebrospinal fluid
Surrounds all exposed surfaces of CNS
Function - cushion, support, transport of nutrients and chemical messengers and waste products
What are the 12 cranial nerves?
olfactory, optic, occulomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, accessory, hypoglossal
What is the olfactory nerve?
Sensor
Receptor- olfactory epithelium in nasal cavity
What is the optic nerve?
Sensor
Receptor in the retina
Input from receptors in the eye through optic foramina of the orbits
What is the occulomotor nerve?
Motor
Control eye movement
Innervates 4 of the 6 extrinsic muscles
What is the trochlear nerve?
Motor
Moves the eye down and laterally
What is the trigeminal nerve?
Sensor and motor
Sensation in eyes, nose, forehead, structures of the mouth.
Motor control of the chewing muscles
What is the abducens nerve?
Motor
Motor control for the lateral movement of the eye
What is the facial nerve?
Sensor and motor
Sensation of taste, motor control of facial expressions, tear gland and salivary glands
What is the vestibulocochlear (acoustic) nerve?
Sensor
Balance and hearing
What is the glossopharyngeal nerve?
Sensor and motor
Sensation of taste, motor control of pharyngeal muscles for swallowing
What is the vagus nerve?
Sensor and motor
Wide roles in abdomen and thorax
Key in cv system
What is the accessory nerve?
Motor
Motor control of the neck and upper back muscles
What is the hypoglossal nerve?
Motor
Motor control of muscles in the tongue
