Homeostasis - Nervous System + Nerve Signaling

Question 1

What is neural signaling?

Answer 1

A process that allows for communication by neurons

Question 2

What are the four components of neural signaling?

Answer 2

1. Reception: detection of stimulus
2. Transmission: movement of messages along neuron to another neuron, muscle, or gland
3. Integration: integration of neural messages + determination of appropriate response
4. Response: output of action resulting from integration

Question 3

Afferent neuron

Answer 3

Neuron that carries impulses from sensory receptors to central nervous system (control centre)

Also called sensory neuron

Question 4

Interneuron

Answer 4

Local circuit neuron of central nervous system that relays impulses between afferent + efferent neurons

Question 5

Efferent neuron

Answer 5

Neuron that carries impulses from central nervous system to effector

Also known as motor neuron

Question 6

Neuron structure

Answer 6

• Enlarged cell body: contains nucleus + most organelles
• Dendrites: projections of cytosol that carry signals towards nerve cell body
• Axons: extensions of cytosol that carry nerve signals away from cell body

Question 7

Glial cells

Answer 7

Neurons are highly specialized + require assistance of other cells for structural support + nutrition. These cells are called glial cells

Question 8

Schwann cells

Answer 8

• One type of glial cell
• Form an insulating cover over the axon of a nerve cell called the myelin sheath, which acts as an electrical insulator
• Gaps between sections of myelin sheath, called nerves of Ranvier, give nerve cell access to extracellular fluid
• Arrangement speeds up rate of travel of electrical impulses along axons

Question 9

Central nervous system (CNS)

Answer 9

Body’s coordinating centre for mechanical and chemical actions, made up of brain + spinal cord

Question 10

Peripheral nervous system (PNS)

Answer 10

All parts of nervous system, excluding brain + spinal cord, that relay information between CNS + other parts of the body

Question 11

Afferent system vs efferent system

Answer 11

Division of the PNS

• Afferent system receives input through receptors + transmits to CNS
• Efferent system carries signals from CNS to effectors (muscles + glands)

Question 12

Somatic vs autonomic system

Answer 12

Division of the efferent system

• Somatic system is composed of efferent neurons that carry signals to skeletal muscles
• Autonomic system is composed of efferent neurons that carry signals to internal organs and glands

Question 13

Sympathetic vs parasympathetic divisions

Answer 13

Division of the autonomic system

• Sympathetic division is involved w/ situations involving stress, danger, excitement, or strenuous activity. Increases heart rate + pressure, dilates airways, induce sweating, + dilate pupils
• Parasympathetic division is involved w/ low stress situations such as relaxing. Reduces effects of sympathetic division + allows for maintenance activities such as digestion

Question 14

What are reflex arcs?

Answer 14

• Neural circuits that travel through spinal cord, but do not require coordination of brain
• Allows for reflex actions such as jerking hand away when touching something really hot
• The time required to consciously process the information could result in injury
• Save time

Question 15

Resting potential

Answer 15

• Neuron not transmitting an impulse
• K+ ions diffuse easily across membrane, Na+ do not diffuse -> resulting in high concentration of both outside membrane
• Inside cell is negatively charged while outside is positive
• Membrane is polarized due to charge separation across it

Question 16

Depolarization

Answer 16

• When neuron is stimulated, it begins to transmit a nerve impulse
• Na+ gates open, K+ gates close. Na+ ions rush into neuron because it is more negative than exterior, K+ cannot leave neuron
• Interior of cell becomes more positive than exterior
• Reversal of charged across membrane is called depolarization

Question 17

Repolarization

Answer 17

• Once nerve cell membrane potential becomes positive, Na+ gates close and K+ gates open
• Sodium-potassium mump uses active transport to move Na+ out and K+ into neuron
• Rapidly restores original polarity of membrane
• Once repolarized, neuron can transmit another impulse

Question 18

Movement of action potential

Answer 18

• Rapid depolarization of nerve cell membrane is referred to as the action potential. It is transmitted down the neuron in a wave-like manner, depolarization is followed by repolarization
• Accomplished by flow of positive ions from depolarization region to adjoining portion (negatively charged) of membrane.
• Flow of ions causes electrical disturbance that sets up the depolarization of the next region

Question 19

Chemical synapses

Answer 19

• Connection between neurons/neuron-effector in which neurotransmitters move from presynaptic cell to postsynaptic cell through synaptic cleft
• When action potential reaches chemical synapse, neurotransmitters are released. They diffuse across synapse + bind w/ receptors on postsynaptic cell which triggers action potential in postsynaptic neuron

Question 20

Electrical synapses

Answer 20

• Connection between neurons/neuron-effector in which presynaptic cell makes direct contact with postsynaptic cell, allowing current to flow via gap junction between cells
• When action potential reaches electrical synapse, it can pass through gap junctions joining pre + postsynaptic neurons, allowing action potential to continue in postsynaptic neuron