Week 5 Lecture Notes

Flashcards covering the structural and functional organization of the nervous system, neurons, neuroglial cells, action potentials, brain components, spinal cord structure, and sensory receptors.

Glial cells

Support, nourish, and protect 90% of cells in the nervous system, are able to divide and generate.

Neurons

Main functional cells of the nervous system, 10% of nervous system cells, unable to generate.

Astrocytes

Found in the CNS, star-shaped, largest, and most plentiful of glial cells. Function includes the creation of the blood-brain barrier, structural support, and scar formation in the CNS after injury.

Microglia

Found in the CNS, small cells with many spine-like processes, defense cells, function as phagocytes in removing cellular debris and damaged nervous tissue, and destroy microbes.

Ependymal cells

Found in the CNS, epithelial-like cells found in the lining of the ventricles of the brain and the central canal of the spinal cord. Function includes production and circulation of cerebrospinal fluid.

Oligodendrocytes

Found in the CNS, produce myelin (insulator), wrap their processes (myelin) around axons and neurons, assists in the conduction of action potentials down a neuron.

Satellite cells

Found in the PNS, are flat cells, cover neuron bodies, support and protect neurons, and control the extracellular environment.

Schwann cells

Found in the PNS, similar to Oligodendrocytes in function of producing myelin, they wrap themselves around one part of a neuron axon, they assist in the conduction of action potentials down a neuron.

Excitable (neuron property)

Responds to environmental changes.

Conductive (neuron property)

Sends electrical signals.

Secretory (neuron property)

Secretes neurotransmitters.

Unipolar neuron

A single process extending from the cell body.

Bipolar neuron

Two processes extending from the cell body.

Pseudounipolar neuron

One process extending that then splits into two.

Multipolar neuron

Multiple processes extending from the cell body.

Nerve structure

Wrapped in endoneurium, bundled together to form a fascicle that is wrapped in perineurium. The fascicles are bundled together to form a nerve that is wrapped in epineurium.

Membrane potential

The difference in the charge between the extracellular and the intercellular environment of a cell.

Voltage-gated channel

Responds to changes in electrical charge; active transport of Na+ or K+.

Leakage (Na+, K+) channel

Always open or leaking, flow with the concentration gradient (passive transport).

Sodium-potassium pump

Uses ATP to continuously pump ions against the concentration gradient (active transport).

Action potential

Occur as a result of rapid change in the membrane potential; an all-or-nothing event.

Resting stage of action potential

Membrane potential is at -70mv, Leakage Na+/K+ channel open and Na+/K+ pump active, Voltage-gated (Na+/K+) channels both closed.

Threshold stage of action potential

Voltage climbs to -55mv (threshold), Leakage Na+/K+ channel open and Na+/K+ pump active, Triggers voltage-gated Na+ channel to open, K+ closed.

Depolarization stage of action potential

A rapid influx of positive ions (Na+) INTO the cell and the voltage becomes more positive, voltage-gated Na+ channel to open, K+ closed, Leakage Na+/K+ channel open and Na+/K+ pump active.

Peak stage of action potential

Intercellular voltage reaches +40mv, Voltage-gated Na+ channel closed, K+ opens, Leakage Na+/K+ channel open and Na+/K+ pump active.

Repolarization stage of action potential

A rapid efflux of positive ions (K+) OUT of the cell and the voltage becomes more negative, Voltage-gated Na+ channel closed, K+ opens, Leakage Na+/K+ channel open and Na+/K+ pump active.

Hyperpolarization stage of action potential

Voltage-gated Na+ channel closed, (K+) is now closed, Leakage Na+/K+ channel open and Na+/K+ pump active, Voltage returns to -70mv and the resting membrane potential is restored.

Saltatory conduction

Only occurs on myelinated neurons, action potential jumps and restarts at each gap in the myelin (nodes of Ranvier), faster transmission.

Continuous conduction

Only occurs on unmyelinated neurons, one single action potential travels the entire axon, slower transmission.

Cerebrum

Left and right hemispheres; left controls RHS and right controls LHS.

Cerebellum

Hand and eye coordination.

Diencephalon

Thalamus, hypothalamus.

Brainstem

Midbrain, pons, medulla oblongata; regulates temperature, heart rate, swallowing, breathing.

Frontal lobe

Primary motor cortex, movement, personality, thinking.

Parietal lobe

Primary somatosensory cortex perception, spelling, maths.

Temporal lobe

Primary auditory cortex, sounds, memory, language, and facial recognition.

Occipital lobe

Primary visual cortex vision, colour identification.

Spinal cord

Column of nervous tissue that connects the brain to PNS, forms a 2-way communication between the brain and the rest of the body, contains different regions that correspond to areas to the body: cervical, thoracic, lumbar, sacral.

Spinal nerves

Anterior/ventral roots contain motor neurons, Posterior/dorsal contain sensory neurons. Spinal nerves form where the anterior and posterior roots come together as they exit in the spinal cord.

Thermoreceptors

Detect temperature.

Mechanoreceptors

Detect touch, pressure.

Chemoreceptors

Detect chemical stimuli.

Photoreceptors

Detect light.

Nociceptor

Detect pain.