anatomy unit 2 nervous system cells and organization notes

ANATOMY

Unit 2 Notes:Cells &

Organization

(1) Neurons• Neuron = Nerve Cell• Types: Multipolar + Unipolar

• Basic Structural Components:– Dendrites (Incoming)– Cell Body (Integrate + Process)– Axon (Outgoing)– Myelin Sheath (Insulation + Speed)– Axon Terminal (Final Destination)

(2) Unipolar Neurons• Use: Afferent Input (Sensory Input)

• Main Job:– Get message to CNS– Let CNS process and decide(NO need to have cell body right by dendrites)

• Process:– Dendrites connected to sensory organ– Message sent to cell body Out Axon– Message sent out of axon terminal

(3) Multipolar Neurons• Use: Efferent Output (Motor Output)

• Main Job:– Organize messages by importance– Make organs do things(Important to have cell body right next to dendrites)

• Process:– Cell body directly connected to dendrites– Dendrites coming from CNS / Efferent path effected organ

(4) Neuroglia• Function: Support, insulate and protect neurons.– Cannot transmit nerve impulses– Can continuously divide through mitosis

• Types:– Astrocytes– Microglia– Ependymal– Oligodendrocytes– Schwann Cells & Satellite Cells

(5) Astrocytes• Connect neurons to capillaries

• Transfer blood-nutrients to neurons (and neuron waste to blood)

(6) Microglia• Phagocytize neuron debris and infectious agents.

(7) Ependymal Cells• Pillow-Shaped cells• Line brain and spinal cord cavities• Beat cilia + Circulate cerebrospinal fluid• Provide Shock Absorption

(8) Oligodendrocytes• Flat, Straw-Shaped cells• Wrap around a neuron’s axon• Fatty insulation for axon (myelin sheath)

(9) Schwann & Satellite Cells• Schwann Cell:– Form Myelin Sheath around axons–Cover Oligodendrocytes

• Satellite Cell:–Protective Cushioning– Surround Cell body of neurons

(10) Junctions• Junction = Meeting of Neuron + Neuron or Neuron

+ Organ– A.K.A. Synapse, Synaptic Cleft

• Nerve Impulse Axon Axon Terminal Release Neurotransmitter– Neurotransmitter = Chemical Message– Causes an effect– Binds with cell membrane on other side

(11) Nervous System OrganizationCENTRAL NERVOUS SYSTEM

PERIPHERAL NERVOUS SYSTEM(SENSORY / AFFERENT INPUT)

PERIPHERAL NERVOUS SYSTEM(MOTOR / EFFERENT OUTPUT)

BODY(INITIAL STIMULUS

/ IMBALANCE)

AUTONOMIC(INVOLUNTARY)

SOMATIC(VOLUNTARY)

PARASYMPATHETIC(REST & DIGEST)

SYMPATHETIC(FIGHT / FLIGHT)

(12) Defining the Levels• Sensory = Afferent = Going to the CNS

• Motor = Efferent = Going away from the CNS

• Somatic = Voluntary

• Autonomic = Involuntary

• Sympathetic = Emotional

• Parasympathetic = Non-Emotional

(13) Voluntary Responses• Voluntary = You consciously choose to move a

body part / respond.

• Pathway:

Stimulus

Sensory / AfferentDivision

Central Nervous System

Motor / EfferentDivision

Effector Organ

Somatic Division

(14) Involuntary Emotional Responses• Involuntary = Without control.• Emotional = Scared, Anxious, Angry, Happy,

Excited

• Pathway:

Stimulus

Sensory / AfferentDivision

Central Nervous System

Motor / EfferentDivision

Effector Organ

Autonomic Division

Sympathetic Division

(15) Involuntary Non-Emotional Responses

• Involuntary = Without control.• Non-Emotional = Every day homeostatic

mechanisms.

• Pathway:

Stimulus

Sensory / AfferentDivision

Central Nervous System

Motor / EfferentDivision

Effector Organ

Autonomic Division

Parasympathetic Division