Homeostasis - Nervous System + Nerve Signaling Flashcards
What is neural signaling?
A process that allows for communication by neurons
What are the four components of neural signaling?
- Reception: detection of stimulus
- Transmission: movement of messages along neuron to another neuron, muscle, or gland
- Integration: integration of neural messages + determination of appropriate response
- Response: output of action resulting from integration
Afferent neuron
Neuron that carries impulses from sensory receptors to central nervous system (control centre)
Also called sensory neuron
Interneuron
Local circuit neuron of central nervous system that relays impulses between afferent + efferent neurons
Efferent neuron
Neuron that carries impulses from central nervous system to effector
Also known as motor neuron
Neuron structure
- 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
Glial cells
Neurons are highly specialized + require assistance of other cells for structural support + nutrition. These cells are called glial cells
Schwann cells
- 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
Central nervous system (CNS)
Body’s coordinating centre for mechanical and chemical actions, made up of brain + spinal cord
Peripheral nervous system (PNS)
All parts of nervous system, excluding brain + spinal cord, that relay information between CNS + other parts of the body
Afferent system vs efferent system
Division of the PNS
- Afferent system receives input through receptors + transmits to CNS
- Efferent system carries signals from CNS to effectors (muscles + glands)
Somatic vs autonomic system
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
Sympathetic vs parasympathetic divisions
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
What are reflex arcs?
- 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
Resting potential
- 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
Depolarization
- 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
Repolarization
- 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
Movement of action potential
- 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
Chemical synapses
- 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
Electrical synapses
- 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
