Exam Iii - Nervous System

Front 1

astrocyte

Back 1

A neuroglial cell of the central nervous system that supports neurons and contributes to the blood-brain barrier.

Front 2

Motor Neuron (splints into Autonomic / Somatic)

Back 2

A nerve cell forming part of a pathway along which impulses pass from the brain or spinal cord to a muscle or gland. (away) "Efferent" are neurons that carry signals from the spinal cord to the muscles to produce movement. Motor division conducts action potentials to the periphery.

Front 3

Sensory neuron

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a neuron conducting impulses (toward) "afferent" to the brain or spinal cord. A nerve cell that conducts impulses from a sense organ to the central nervous system.

Front 4

Microglia

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a type of glial cell that are the resident macrophages of the brain and spinal cord, and thus act as the first and main form of active IMMUNE DEFENSE in the central nervous system (CNS)

Front 5

macrophages

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They are specialized phagocytic cells that attack foreign substances, infectious microbes and cancer cells through destruction and ingestion

Front 6

Ependymal cell

Back 6

Production & Circulation of cerebrospinal fluid (CSF). Responsible for the lining of ventricular cavities (of brain). They also line the central canal of spinal cord.

Front 7

Oligodendrocyte / Schwann cell

Back 7

surround axons, insulating them
– Myelin sheaths = insulation
– Support cell wraps around axon multiple times, forming myelinated axons
– No support cells = unmyelinated axon - these transmit messages more slowly

Front 8

Nervous System Functions

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-GATHER sensory information (internal & external)
-PROCESS sensory information (respond)
-DIRECT (cause muscle movement)
-MAINTAIN homeostasis (control center)
-THINK (memory, logic, personality, etc.)

Front 9

Nervous System Composed of...

Back 9

– Central nervous system (CNS)
• Brain & spinal cord
– Peripheral nervous system (PNS)
• Nerves & ganglia
Both CNS and PNS work together to produce all the functions of the nervous system

Front 10

Neurons Composed of...

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Cell body
+ dendrites
+ axon (single or may branch)
– Nissl bodies ex. rough ER
– Axon hillock
– Collateral axons
– Myelin sheath
– Nodes of Ranvier

Front 11

Neuron Types

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• Multipolar: ‘typical’ single axon, many dendrites
• Bipolar: single dendrite, axon
• Pseudo-unipolar: ‘split’ single axon

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Multipolar

Back 12

‘typical’ single axon, many dendrites (example of a motor neuron)

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Bipolar

Back 13

single dendrite, axon (ex. photo reception eyes)

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Pseudo-unipolar

Back 14

‘split’ single axon

Front 15

Neuron Support Cells

Back 15

Neuroglia (aka glial cells)
– Astrocytes: physically support; blood/brain barrier
– Microglia: immunity/CNS defense
– Ependymal cells: produce, circulate cerebrospinal fluid
– Oligodendrocytes: CNS support (Schwann cells in PNS)

Front 16

Astrocytes

Back 16

physically support; blood/brain barrier

Front 17

Microglia

Back 17

immunity/CNS defense

Front 18

Ependymal cells

Back 18

produce, circulate cerebrospinal fluid

Front 19

Oligodendrocytes

Back 19

CNS support (Schwann cells in PNS)

Front 20

Oligodendrocytes and Schwann cells

Back 20

surround axons, insulating them
– Myelin sheaths = insulation
– Support cell wraps around axon multiple times, forming myelinated axons
– No support cells = unmyelinated axon - these transmit messages more slowly

Front 21

How Nerves ‘Speak’
• Electricity

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– Small voltage difference between inside axon & outside = polarized
– Resting membrane potential: polarity found in normal cell
• + outside, - inside
• Based on what ions (K+, Na+) can cross membrane through channels
– Chemical (neurotransmitter) or voltage gated

Front 22

Action Potentials

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• When electricity passes along axon, opens voltage-gated channels, allowing
Na+ to enter cell, depolarizing it IF threshold is reached
– All action potentials that are initiated are the same strength (all-or-none); not variation in signal strength, but in signal frequency that causes different responses
• When charge passes, Na+-channels close, NaK pump removes Na+ and cell repolarizes (returns to resting membrane potential)

Front 23

Saltatory Conduction

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charge ‘jumps’ from Node of Ranvier to Node of Ranvier through cytoplasm & external fluid (why myelinated axons transmit messages faster than
non-myelinated axons)

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At the End of the Axon…
• Synapse!

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– Junction between nerve & what it interacts with (other nerve, muscle, etc)
– End of axon = pre-synaptic terminal
– Recipient cell = postsynaptic membrane
– Between space = synaptic cleft
– Charge doesn’t cross synaptic cleft, use neurotransmitter to pass message
• Acetylcholine (ACh), norephinephrin, dopamine, serotonin, endorphins

Front 25

Peripheral Nervous System

Back 25

Non-CNS (ie. outside the spinal cord & brain)
– Sensory (afferent) (toward the CNS)
• Sensory neurons
– Motor (efferent) (away from the CNS)
• Motor neurons
– Somatic (voluntary)
– Autonomic (involuntary)
» Sympathetic (‘up’)
» Parasympathetic (‘down’)
– Enteric (digestion)

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Central Nervous System
• Spinal cord & brain

Back 26

1. Brainstem
• Connects to spinal cord
• Regulates vital functions (breathing, heart rate)
2. Diencephalon
• Between brainstem & cerebrum
• Emotions, hormones, behaviors
3. Cerebellum
• Posterior from brainstem
• Balance, fine motor control
4. Cerebrum
• ‘Brain’
• Receive/synthesize information

Front 27

Brainstem

Back 27

• Medulla Oblongata
– Inferior (connects to spinal cord)
– Responsible for maintaining/regulating normal vital processes (w/Pons)
– Raised pyramids on anterior surface transmit information from brain to spinal cord (& body) for skeletal muscle control
• Pons
– Superior to Medulla Oblongata
– Communication between cerebellum & cerebrum
– W/Medulla Oblongata regulate some vital functions (balance, swallowing)
• Think mouth/lungs
• Midbrain
– Superior to Pons (v. small)
– 4 colliculi relay auditory, touch & visual information
• Inferior colliculi: transfer sound info to CNS
• Superior colliculi: reflexive reactions to sound, light, or touch
– Substantia nigra helps coordinate body movements
• Reticular formation: group of brain cells used to regulate cyclic functions

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Brainstem

Back 28

- Connects to spinal cord
- Regulates vital functions (breathing, heart rate)

Front 29

Diencephalon

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• Between brainstem & cerebrum
• Emotions, hormones, behaviors

Front 30

Cerebellum

Back 30

• Posterior from brainstem
• Balance, fine motor control

Front 31

Cerebrum

Back 31

• ‘Brain’
• Receive/synthesize information

Front 32

Medulla Oblongata

Back 32

– Inferior (connects to spinal cord)
– Responsible for maintaining/regulating normal vital processes (w/Pons)
– Raised pyramids on anterior surface transmit information from brain to spinal cord (& body) for skeletal muscle control

Front 33

Pons

Back 33

– Superior to Medulla Oblongata
– Communication between cerebellum & cerebrum
– W/Medulla Oblongata regulate some vital functions (balance, swallowing)
• Think mouth/lungs

Front 34

Midbrain

Back 34

– Superior to Pons (v. small)
– 4 colliculi relay auditory, touch & visual information
• Inferior colliculi: transfer sound info to CNS
• Superior colliculi: reflexive reactions to sound, light, or touch
– Substantia nigra helps coordinate body movements
• Reticular formation: group of brain cells used to regulate cyclic functions

Front 35

Substantia nigra

Back 35

helps coordinate body movements

Front 36

Diencephalon

Back 36

• Thalamus
– 2 halves connected by interthalamic adhesion
– Transfer sensory input from brainstem to cerebrum
– Influences mood/emotions, recognize pain
• Epithalamus
– Curls around posterior thalamus
– Involved in scent memory
– Contains pineal gland (produces hormones; may influence long-term cyclical behavior)
• Hypothalamus
– Anterior, inferior to thalamus
– Maintainance of homeostasis (ie. perceptions of hunger); physical responses
to emotions; hormonal control (esp. puberty/reproduction)
– Connects to pituitary gland via infundibulum
– Posterior region contains mammillary bodies involved in scent memory

Front 37

Thalamus

Back 37

– 2 halves connected by interthalamic adhesion
– Transfer sensory input from brainstem to cerebrum
– Influences mood/emotions, recognize pain

Front 38

Epithalamus

Back 38

– Curls around posterior thalamus
– Involved in scent memory
– Contains pineal gland (produces hormones; may influence long-term cyclical behavior)

Front 39

Hypothalamus

Back 39

– Anterior, inferior to thalamus
– Maintainance of homeostasis (ie. perceptions of hunger); physical responses
to emotions; hormonal control (esp. puberty/reproduction)
– Connects to pituitary gland via infundibulum
– Posterior region contains mammillary bodies involved in scent memory

Front 40

Cerebellum

Back 40

Attached to brainstem (posterior) by cerebellar peduncles
– ‘Wrinkled’ appearance similar to cerebrum, but smaller
– Used to maintain balance (proprioceptive neurons) and learning/coordinating fine motor movements

Front 41

proprioceptive neurons

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Balance-> Orientation of where you are relative to other parts.

Front 42

Cerebrum

Back 42

Largest part of brain
– Split by longitudinal fissure into R & L hemispheres
– ‘wrinkled’ appearance due to folds that increase surface area
• Gyri = folds
• Sulci = grooves
• More vocab:
– Grey matter = clusters of neuron cell bodies (‘brain’)
» On the brain surface (superficial) = cortex
» Deeper in the brain = nuclei
» When found in the PNS = ganglia
– White matter = nerve axons in sheaths (‘nerves’)

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Gyri

Back 43

folds in cerebrum

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Sulci

Back 44

grooves

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Grey matter

Back 45

clusters of neuron cell bodies (‘brain’)
» On the brain surface (superficial) = cortex
» Deeper in the brain = nuclei
» When found in the PNS = ganglia

Front 46

White matter

Back 46

nerve axons in sheaths (‘nerves’)

Front 47

Connecting CNS to PNS

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• Spinal cord:
– Grey matter (central) horns
• Posterior
• Anterior
• Lateral
– White matter (peripheral) columns (ascending/descending tracts)
• Dorsal
• Ventral
• Lateral

Front 48

Grey matter (central) horns

Back 48

• Posterior
• Anterior
• Lateral

Front 49

White matter (peripheral) columns (ascending/descending tracts)

Back 49

• Dorsal
• Ventral
• Lateral

Front 50

Neuronal Pathways

Back 50

• Converging vs. diverging
– Converging: multiple nerves merge to one
– Diverging: nerve connects to multiple nerves

Front 51

Converging pathway

Back 51

multiple nerves merge to one

Front 52

Diverging pathway

Back 52

nerve connects to multiple nerves

Front 53

Reflexes

Back 53

• Involuntary response to a stimulus (doesn’t need to go through CNS before reacting)
– A reflex arc = simplest nervous pathway
1. Sensory receptor
2. Sensory neuron
3. (interneuron)
4. Motor neuron
5. Effector

Front 54

A reflex arc

Back 54

simplest nervous pathway
1. Sensory receptor
2. Sensory neuron
3. (interneuron)
4. Motor neuron
5. Effector

Front 55

Nissl Bodies

Back 55

is a large granular body found in neurons. These granules are rough endoplasmic reticulum (RER)

Front 56

Axon Hillock

Back 56

is the last site in the soma where ACTION POTENTIALS propagated from synaptic inputs are summated before being transmitted to the axon.

Front 57

Nodes Ranvier

Back 57

periodic gap in the insulating sheath (myelin) on the axon of certain neurons that serves to facilitate the rapid conduction of nerve impulses.