Nervous System P.3 Katheryn Castro-Navarro
Brain -largest and most complex part of the NS
Cerebrum-Largest part; associated with higher brain functions, and sensory/motor functions
Diencephalon-Processes sensory input and controls homeostatic processes
Cerebellum-coordinates muscular activity
Brainstem-coordinates and regulates visceral activities, and connects different parts of the NS
Spinal cord-begins at the base of the brain
Consists of 31 segments that connect to a pair of spinal nerves
White matter that's made of bundles of myelinated fibers surround the butterfly shaped core of gray matter
Central canal is in the middle of gray matter and contains cerebrospinal fluid
Cell bodies of sensory neurons enter the spinal cord and is found in the dorsal root ganglia out of the spinal cord
Upper and lower wings of gray matter form post and ant horns between the lateral horn
Major functons include transmitting impulses to and from the brain and to house spinal reflexes
Ascending tracts carry sensory info to the brain; descending tracts carry motor info from brain to muscles or glands
Spinal reflexes; controlled by reflexor arcs that pass through spinal cord
Major Functions of the NS-thinking, movement, internal processes of physiology
CNS
Made up of brain and spinal cord
responsible for decision making
Somatic NS
Controls voluntary skeletal muscles
PNS
Autonomic NS
Controls individual effectors (smooth/cardiac muscles, and glands)
Made up of cranial and spinal nerves that connect the CNS to the rest of the body
Tissues
Neurons
Contains cell body, tubular cytoplasm-filled dendrites, and a cytoplasm axon
Cell body contains major organelles including the nucleus
Dendrites conduct impulses toward the cell body; short and branching, they provide the receptive for communication wit other neurons
The axon conducts impulses away from the cell body; it arises from a thickening extending from the cell body, called axon hillock
Neurologia
"Nerve glue" are cells that support neurons
Fill spaces, structurally supports, protects, and insulates neurons
Doesn't generate or conduct nerve impulses
4 types in the CNS and 2 types in the PNS
CNS-
PNS-
Microglia: Small, functions as phagocytes, for bacterial cells and cellular debris, and produces scar tissue in sites of injury
Oligodendrocytes: From myelin sheath around axons in brain/spinal cord
Ependymal cells: produces cerebrospinal fluid in CNS
Astrocytes: Lie between blood vessels and neurons
Schwann cells: myelin, produces neuroglia of PNS
Sattelite cells: produces protective coating around cell bodies of neurons in PNS
Cranial Nerves
12 Pairs of cranial nerves that arise from underside of the brain
Most are mixed nerves that contain sensory and motor nerve fibers, some are only sensory while others are primarily motor
First pair arises from cerebrum 2nd pair arises from thalamus, and most arise from the brainstem
12 pairs designated by number and name; they're in order from superior to inferior
Spinal Nerves
31 pairs of spinal nerves that arise from the spinal cord
the first pair is the only one that is mixed nerves
grouped according to level of where the arise
8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves, and 1 pair of coccygeal nerves
Each arises from 2 roots; a sense of dorsal root and a motor ventral root
Each dorsal root contains dorsal root ganglia, which house cell bodies of sensory neurons entering the spinal cord
Ventral root and dorsal root unite to form the spinal nerve that extends out of the vertebral canal through intervertebral foramen
Neurotransmitter
Chemical messengers on the synapse that convey an electric impulse from a neuron to another cell
Reflex arc(major parts and functions)
Receptor
Receptor end of dendrite or a specific receptor cell in sensory organ
senses specific type of receptor into the brain from the spinal cord
Interneuron
Dendrites, CB, and axon of a neuron within the brain and spinal cord
carries info from sensory neuron to motor neuron
Sensory neuron
Dendrite, cell body, and axon of sensory neuron
carries info from receptor into the brain and from the spinal cord
Motor neuron
Dendrite, cell body, and axon of a motor neuron
Carries instruct from brain or spinal cord out the effector
Effector
Respond to stimuli (inhibition) by motor neuron and produces reflex or behavioral action
Disorders/Dieseases
Cerebrovascular Accident
occurs when blood flow to portion of brain is halted
Causes and Risk factor
Certain types are hereditary
Diabetes
High cholesterol
Symptoms and treatments
Severe headache
loss of balance and coordinaton
Confusion or memory loss
And
Hospitalization
blood thinners
stroke rehab
Autism-Brain disorder that makes it difficult to communicate
Causes and risk factors
certain types are hereditary
Symptoms and treatments
Anxiety
depression
unnatural attachment to or routine or object
and
medications
coping skills
anxiety management
Meningitis-infection in meninges surrounding the brain
Causes and risk factors
certain types are hereditary
Symptoms and treatment
stiff neck
fever chills
irritation
and
antibiotics
bacterial hospitalization
medications
Multiple Sclerosis- Autoimmune disease that damage myelin sheath
Causes and risk factors
certain types are hereditary
Symptoms and treatments
Muscle weakness
depression
frequent urination
and
no cure
steroid treatments
assistive devices
Action potential and Nerve impulse
Action potential
Neurons are chill until stimulated
stimuli can change resting potential in any direction
excilatory stimulus opens chemical gated Na+ channels
Na+ ions flow into cell due to gradient, causing inside of neuron to become less
Threshold stimulus: strong enough to cause many Na+ ions to enter neuron, that potential charges from -70mv to -55mv
Once it reaches threshold potential volt gated Na+ channels open, charge becomes +30mV and that's called action potential
Nerve Impulse
Signal transmitted across a nerve fiber
Consists of wave electric depolarization that reverses the potential diff across the nerve cell membranes
Autonomic and sympathetic
Both respond to eternal stimuli
sympathetic NS responds to external stimuli by prepping body for flight or fight and somatic NS responds to external stimuli by sending info to sensory receptors, spinal cord, and brain
autonomic NS has 2 sub components, sympathetic NS has one
SNS has motor and sensory pathways, while ANS has motor
ANS controls internal organs and glands, while SNS controls muscles and movements