Key Concepts in Nervous System and Muscle Physiology

CNS

The brain and spinal cord.

PNS Divisions

Sensory (afferent) and Motor (efferent) divisions.

Somatic Afferents

Sensory info from skin, muscles, joints.

Visceral Afferents

Sensory info from organs and membranes.

Somatic Nervous System

Voluntary control of skeletal muscles.

Autonomic Nervous System

Involuntary functions of organs and glands.

Schwann Cells

Form myelin sheaths in the PNS.

Oligodendrocytes

Form myelin sheaths in the CNS.

Graded Potentials

Local changes in membrane potential; not all-or-none.

Action Potential Trigger

Depolarization to threshold (-50 mV) at the axon hillock.

Depolarization

Na channels open, Na enters the cell.

Repolarization

K channels open, K exits the cell.

Absolute Refractory Period

No new AP can occur while Na channels are open.

Saltatory Conduction

AP jumps between nodes of Ranvier in myelinated axons.

Synaptic Knob

Releases neurotransmitters into the synaptic cleft.

EPSPs

Depolarize the postsynaptic membrane.

IPSPs

Hyperpolarize the postsynaptic membrane.

ACh Breakdown Enzyme

Acetylcholinesterase (AChE).

ACh

Excitatory in skeletal muscle, inhibitory in heart.

Dopamine Deficiency Disease

Parkinson's disease.

Sarcomere

The functional unit of muscle contraction.

Thin Filament Proteins

Actin, tropomyosin, troponin.

Ca Release Trigger

Depolarization of T-tubules.

Power Stroke

Myosin pulls actin inward during contraction.

Myosin Detachment Cause

Binding of ATP.

Rigor Mortis

Muscle stiffness after death due to no ATP.

Neuromuscular Junction (NMJ)

Synapse between motor neuron and muscle fiber.

Muscle Depolarization

Na enters the sarcolemma.

Latent Period

Time between stimulus and contraction.

Tetanus in Muscle

Sustained contraction without relaxation.

Motor Unit

One motor neuron and all the muscle fibers it stimulates.

Fatigue-Resistant Fibers

Red slow-twitch fibers.

Fast-Twitch Fibers

White fast-twitch fibers.

Isometric Contraction

Tension without muscle shortening.

Isotonic Contraction

Muscle shortens while maintaining tension.

Tension

Tension with muscle shortening (movement).

Cellular respiration equation

CHO + 6O 6CO + 6HO + energy (ATP)

Glycolysis location

In the cytoplasm.

Net gain of ATP from glycolysis

2 ATP.

Final electron acceptor in aerobic respiration

Oxygen.

Function of NAD

Carries electrons to the electron transport chain (ETC).

Krebs cycle location

In the mitochondrial matrix.

Total ATP yield from one glucose molecule

3638 ATP.

Chemiosmosis

ATP synthesis using H gradient across inner mitochondrial membrane.

Oxygen unavailability effect

Cells undergo fermentation.

Product of lactic acid fermentation

Lactic acid.

Poison that blocks the ETC

Cyanide.

Process that generates the most ATP

Oxidative phosphorylation.

Substrate-level phosphorylation

Direct ATP production during glycolysis and Krebs cycle.

Products of the Krebs cycle per glucose

2 ATP, 6 NADH, 2 FADH.

Alcoholic fermentation

Glucose ethanol + CO.

Function of astrocytes

Regulate environment and form blood-brain barrier.

Responsibility of microglia

Remove pathogens in CNS.

Function of ependymal cells

Circulate cerebrospinal fluid.

Difference between a tract and a nerve

Tract = CNS; Nerve = PNS.

Retrograde transport in neurons

Movement from axon terminal to soma.

Role of the axon hillock

Initiates action potentials.

Refractory period of a muscle

Muscle cannot respond to another stimulus.

Function of calmodulin and calsequestrin

Bind calcium inside muscle cells.

Graded muscle response

Smooth increase in force by summation or recruitment.

Treppe (staircase effect)

Increased strength of contraction with repeated stimulation.

Muscle tone

Slight, continuous muscle contraction for posture.

Causes of muscle fatigue

Lack of ATP, ionic imbalance, lactic acid.

Function of myoglobin

Stores oxygen in muscle.

Causes of contractures

Lack of ATP causing permanent cross-bridge attachment.

First step of aerobic respiration

Glycolysis.

Pyruvate with oxygen

Converted to acetyl-CoA.

FADH production in the ETC

2 ATP per molecule.

Organelle site of oxidative phosphorylation

Mitochondria.

Organisms that perform alcoholic fermentation

Yeast.

Facultative anaerobes

Organisms that survive with or without oxygen.