exam 4 a&p 1

Astrocytes (CNS)

Star-shaped cells that make up half of neural volume; form the Blood-Brain Barrier (BBB).

Microglia (CNS)

The immune cells of the brain; act as macrophages to engulf microbes and dead cells.

Oligodendrocytes (CNS)

Cells that wrap CNS axons to form the myelin sheath.

Ependymal Cells (CNS)

Line brain ventricles; use cilia to circulate cerebrospinal fluid (CSF).

Schwann Cells (PNS)

Form myelin sheath around nerve fibers in the peripheral nervous system.

Satellite Cells (PNS)

Surround neuron cell bodies in the PNS; similar to astrocytes.

Nodes of Ranvier

Gaps in the myelin sheath that aid impulse transmission.

Amitotic

Neurons lose ability to divide after differentiation.

High Metabolic Rate

Neurons need lots of oxygen and glucose; survive only minutes without them.

Perikaryon

Cytoplasm surrounding the neuron's nucleus.

Nissl Bodies

Clusters of rough ER in neuron cell body.

Axon Hillock

Trigger zone where graded potentials become action potentials.

Axon Terminals

End of neuron containing neurotransmitter vesicles.

Dendrites

Input region that receives signals toward the cell body.

3-Step Process of Homeostasis

Sensory input → Integration → Motor output.

Integration

Interpreting sensory input and deciding response.

Somatic Nervous System

Voluntary control of skeletal muscles.

Autonomic Nervous System

Involuntary system (sympathetic + parasympathetic).

Parasympathetic Nervous System

"Rest and Digest."

Sympathetic Nervous System

"Fight or Flight."

Afferent vs. Efferent

Afferent = sensory (input); Efferent = motor (output).

Excitability

Ability to respond to stimuli.

Contractility

Ability to shorten and do work.

Extensibility

Ability to stretch.

Elasticity

Ability to return to original shape.

Skeletal Muscle

Voluntary, striated, multinucleated, attached to bones.

Cardiac Muscle

Involuntary, striated, heart muscle with intercalated discs.

Smooth Muscle

Involuntary, non-striated, in hollow organs.

Intercalated Discs

Allow cardiac muscle cells to contract as one unit.

Epimysium

Outer covering of entire muscle.

Perimysium

Wraps bundles (fascicles).

Endomysium

Wraps individual muscle fibers.

Sarcolemma

Muscle fiber plasma membrane.

Sarcoplasmic Reticulum

Stores calcium ions (Ca²⁺).

Sarcomere

Functional unit of muscle (Z-line to Z-line).

Myosin vs. Actin

Myosin = thick filaments; Actin = thin filaments.

Troponin & Tropomyosin

Regulate binding; troponin binds Ca²⁺, tropomyosin blocks sites.

Acetylcholinesterase

Breaks down ACh for muscle relaxation.

Creatine Phosphate

Provides ~15 seconds of quick ATP.

Anaerobic Glycolysis

30-40 seconds energy without oxygen; produces lactic acid.

Aerobic Respiration

Long-term ATP production using oxygen.

Muscle Fatigue

Inability to contract despite stimulation.

Oxygen Debt

Extra oxygen needed after exercise to recover.

Muscle Twitch

Single contraction-relaxation cycle.

Tetanus

Sustained contraction from rapid stimulation.

Muscle Tone

Partial contraction in resting muscles.

Rigor Mortis

Muscle stiffening after death due to lack of ATP.

Myasthenia Gravis

Autoimmune disease blocking ACh receptors → weakness.

Multiple Sclerosis (MS)

Loss of myelin in CNS → neurodegeneration.