Exam 4 sample essays

Exam 4 sample essays - SAMPLE ESSAY QUESTIONS FOR FINAL...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: SAMPLE ESSAY QUESTIONS FOR FINAL EXAM 1. What is the difference between a sensory afferent neuron and a motor efferent neuron? Sensory (afferent) carry impulse to the CNS Motor (efferent) carry impulses from CNS Mixed sensory and motor fibers carry impulses to and from CNS; most common type of nerve 2. Describe saltatory conduction and 2 advantages this type of conduction has over continuous conduction. Myelinated axons Myelin does NOT conduct electricity Insulator; prevents ion movement Electrical currents - only at the nodes of Ranvier High concentration of voltage-gated Na+ channels at nodes Action potentials JUMP from one node to the next Advantages : Smaller regions of membrane depolarize, etc. Less energy expended by Na+/K+ pump to reset RMP Increases speed of conduction 3. Name the 4 types of neuroglia in the CNS and a function of each. 1. Astrocytes-Support and brace neurons Anchor neurons to their nutrient supplies (capillaries) Control the chemical environment 2. Microglia-Phagocytes protection from disease 3. Ependymal cells-Line the central cavities of the brain and spinal cord Produce CSF (cerebrospinal fluid) Cilia to help circulated CSF 4. Oligodendrocytes-Branched cells that wrap around axons of neurons Myelin phospholipid covering, insulating function 4. What is the basis for the resting membrane potential (-70 mV)? 5. Define: depolarization, repolarization, hyperpolarization. What ion channels are responsible for these phases? Depolarization the inside of the membrane becomes less negative Na+ permeability increases; membrane potential reverses Na+ gates are opened; K+ gates are closed Threshold a critical level of depolarization (-55 to -50 mV) Repolarization the membrane returns to its resting membrane potential Na+ gates close Voltage-sensitive K+ gates open K+ efflux results in return toward RMP Hyperpolarization the inside of the membrane becomes more negative than the resting potential K+ gates remain open, causing an excessive efflux of K+ Hyperpolarization of the membrane 6. What is the difference between a chemically-gated ion channel and a voltage-gated ion channel? Chemically-gated channels Integral proteins change shape to function as gates Restrict/allow movement dependent on binding of a specific neurotransmitter Voltage-gated channels Integral proteins change shape to function as gates Restrict/allow movement dependent on membrane potential Electrical changes at the membrane change function of gate 7. Describe 2 differences between a graded potential and an action potential....
View Full Document

Page1 / 6

Exam 4 sample essays - SAMPLE ESSAY QUESTIONS FOR FINAL...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online