E2 - Nervous System

Dr. Diaz

What are the three nervous systems?

Central, peripheral, auonomic

Central Nervous System

structure and function of brain and spinal cord

Peripheral Nervous System

Structure and function of cranial nerves and spinal nerves

Autonomic Nervous System

Sympathetic, Parasympathetic

Nerve Cells

Neurons

3 parts of a nueron

cell body, dendrites, axon

cell body

nutritional center of a neuron, filled w high degree of ER

function of ER

metabolizes protein, which gives the cell the nutrients it needs to do its job

Nuclei

collection of cell bodies in CNS

Ganglia

collection of cell bodies PNS

Dendrites

transport info from other cells and pulls it in to the cell body

Axon

transmits info by electrical impulses away from the body

Axon Hillock

junction between cell body and axon

3 structural classifications

Pseudounipolar, bipolar, multipolar

Pseudounipolar

one process exits the body

Bipolar

2 processes exit that exit at the opposite ends of the cell body

Multipolar

multiple dendrites and one axon

3 functional classifications

sensory (afferent), motor (efferent), interneurons (association)

Cerebrum

largest part of the brain; 4 lobes; right and left hemispheres; responsible for higher level functions

4 lobes of cerebrum

parietal, temporal, frontal, occipital

Parietal Lobe

primary sensory cortex of the brain; responsible for the integration of sensory info

Postcentral gyrus

area in the parietal lobe; sensory area of the brain

Temporal Lobe

primary auditory complex, receives info cochlea of inner ear

Wernicke’s Area

in the temporal lobe; allows for language comprehension and understanding

What happens when damage is done to the Wernicke’s Area?

The patient can hear you but cannot comprehend what you said

Frontal Lobe

primary motor cortex

Prefrontal cortex

in frontal lobe; primarily responsible for expressing emotions and judgement

Flat Effect

a stroke in the prefrontal cortex; person cannot show any emotions and lack judgement (makes them a safety risk)

Precentral Gyrus

in the frontal lobe; integration of motor activity

Gyri

peaks in the brain curve

Sulci

dips in brain curves

Broca’s Area

in the frontal lobe; involved in the motor aspect of speech

What happens if there’s a stroke in the Broca’s Area?

the person wants to respond and thy know what to say but don’t have the motor ability to do it. some can sing a bit but it can be unclear

Aphasia

difficulty communicating

Expressive Aphasia

they can not communicate because they can express what they want to say but just can’t physically say it; damage to Broca’s Area

Receptive Aphasia

cannot communicate with you b/c they are not receptive to what you’re saying; damage to Wernicke’s Area

Global Aphasia

have damage to both Broca’s and Wernicke’s Area; damage both receptive and expressive tissues (temporal and frontal)

Occipital Lobe

primary visual cortex of the brain; interpretation of vision and coordination of eye movements

Diencephalon

2 structures; thalamus, hypothalamus

Thalamus

relay center of the brain; made up of 3 types of nuclei

Sensory Nuclei

structures that collect sensory info from face and body and relay to the postcentral gyrus in parietal lobe (b/c its the part of the brain that understands information)

Motor Nuclei

relay info from cerebellum and basal ganglia and send it to the precentral gyrus of the frontal lobe

Other Nuclei

collecting info from the viscera (organs of the body) to the cerebrum and hypothalamus

Hypolthalamus

main structure that regulates autonomic nervous system activity to maintain homeostasis (ex. temp control, fluid balance)

Brain Stem

3 structures; midbrain, pons, medulla oblongata

Midbrain

involved in motor activity

Pons/Medulla Oblongata

involved in breathing control; most people who experience a stroke here are on ventilators; they integrate from cranial nerves

Cerebellum

3 major functions; balance, postural control, coordination

What happens when a person has a stroke in the cerebellum?

do not have good function of the three major functions, look extremely intoxicated (can’t walk well, start swaying)

How to asses coordination?

rapid alternating movements

Limbic System

system in the brain with multiple structures that allows us to do many functions (emotion and motivation, memory)

Emotion and Motivation

function of Limbic System, ability to feel fear, aggression and be goal oriented

New Memory

Amygdala, Hippocampus

Long Term Memory

prefrontal cortex, creates dementia if damaged

Basal Ganglia

major function is to initiate and modulate fine tuning movement (5 types)

Globus Palidus

Internal, External

5 types of nuclei in Basal Ganglia

1. Globus Pallidus
2. Putamen
3. Caudate
4. Subthalamic
5. Substantial Nigra

Striatum

Putamen and Caudate together

What two pathways of the basal ganglia initiate and fine tune movement?

Direct and Indirect pathways

Direct Pathway

starts movement


1. precentral gyrus (sends excitatory signal)
2. Striatum
3. Globus Pallidus Internal
4. Subthalamic Nuclei
5. back to Precentral Gyrus
6. Spinal Cord
7. Spinal Nerves
8. Muscles

Indirect Pathways

stopping movement


1. Precentral Gyrus
2. Striatum
3. Globus Pallidus External
4. Subthalamic Nuclei
5. Globus Pallidus Internal (sends inhibitory signal, stop the movement)
6. Precentral Gyrus

How do we make sure the direct and indirect pathways are initiated at the right time?

substantial nigra

* release extremely important neurohormone called dopamine
* dopamine excites the direct pathway and inhibits the indirect pathways

Parkinson’s

reduced levels of dopamine in the substantial nigra; you do not have good modulation of movement, very jerky movements, hard time initiating movement; develop pill rolling tremors

Spinal Cord

cylindrical mass of nerve tissue from the brain; cervical (7), thoracic (12) lumbar (5)

Grey Matter

primarily consists of the cell bodies and dendrites of neurons (center of spinal cord)

White Matter

Axons of Neurons

Anterior/Ventral Horn

cell bodies of motor/efferent neurons

Posterior/Dorsal Horn

cell bodies of sensory/afferent neurons

Autonomic Nervous System

sympathetic and parasympathetic

Sympathetic Nervous System

fight or flight

* cardio excitatory, GI inhibitory
* increased HR, BP, myocontractility, coronary artery vasodilation (relative peripheral artery vasodilation)
* reduction in peristalsis in GI tract
* get energy by exciting the cardiovascular system, sending more blood to O2 to make energy
* vasodilating coronary arteries; excite the myocardium
* triggered by release of catecholamines (epi/norepi)

Parasympathetic Nervous System

* triggered by the release of the hormone Acetylcholine
* cholinergic response b/c it’s a response to acetylcholine
* cardio inhibitory, GI excitatory
* decreases HR, decreases BP, decreases myocardiocontractility, coronary artery vasoconstriction, relative peripheral artery vasodilation, increases peristalsis in GI tract
* less blood flows to myocardium so it is relatively less stimulated bc of the vasoconstriction

How to control low BP?

1. Baro receptors sense the change in the blood vessels
2. send a signal to the hypothalamus
3. hypothalamus sends signal to adrenal gland
4. adrenal gland releases epi/norepi
5. triggers a sympathetic response (exciting the cardio system)

How to control high BP from nerves?

1. Baro receptors sense the change in blood vessels
2. sends a signal to the hypothalamus
3. calls for release of acetylcholine (from vagus nerve)
4. triggers a parasympathetic response to decrease BP

How to control a high body temp (hyperthermia)?

1. thermal receptors in skin identify the change in temp
2. send a signal to hypothalamus
3. hypothalamus sends signal to adrenal gland
4. adrenal gland releases epi/norepi
5. triggers a sympathetic response (exciting the cardio system)
6. HR increase ill push more blood to the peripheral body that releases heat to the environment

* when you run a fever your HR is higher

How to control low body temp (hypothermia)?

1. thermal receptors identify change in temp
2. sends a signal to the hypothalamus
3. calls for release of acetylcholine (from vagus nerve)
4. triggers a parasympathetic response to decrease BP and HR
5. less blood to peripheral body
6. body holds blood more centrally, conserving heat
* when you’re cold your HR is lower