ANATOMY

Unit 1 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 Organization

CENTRAL 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