Nervous System

Anatomy test for the Nervous System, please review the diagram on the study guide. Lutkus Kahoot: https://create.kahoot.it/share/nervous-system-review/64c57301-2f7e-4f0d-9eff-6c6c36b19f02

Sensory (afferent) neurons

Receives information

Interneurons (spinal cord + brain)

Send signals to the brain, processing information, then send signals to motor neurons

Motor (efferent) nerves

Responding to signals

Reflex Arc

Sends a message back to the motor neuron + brain at the same time

Central Nervous System (CNS)

Brain and Spinal Cord
- Controls the smooth muscles

Peripheral Nervous System (PNS)

Nerves throughout the body, controls the skeletal system

Action Potential

Rapid temporary reverse in electrical charge across a cell membrane pass = gates of potassium channels opening, allowing potassium to flow out

Sodium/Potassium Pump

In the nerve cell membrane pumps, Na⁺ ions out of the cell of the cell and K⁺ ions into the cell. The active transport inside contain more K⁺, less Na⁺ than outside of the cell

Neurotransmitters (NTs)

Chemical signals of neurons that transmit an impulse across the synapse to another cell
→ Lock + key w/receptors

→ The neurons are stored in the neurotransmitters in the axon terminals

Synapse

Space where the axon terminal of one neuron can transfer an impulse to another neuron or cell

• small space between the cells is the synaptic cleft

• axon terminals contain vesicles filled with neurotransmitter

Excitatory NTs

Causes impulses in the next neuron

• speed up transmission over the synapse

Inhibitory NTs

Stops an impulse from being sent in the next neuron

Agonist

Molecule same effect on the post synaptic neuron as the neurotransmitter itself does

Antagonist

Molecule blocks the effect that the neurotransmitter normally has on the postsynaptic neuron

Cell body

contains the nucleus and other cell organelles

Dendrites

Short, numerous fibers that receive information

Axon

Single long fibers, conducts information away from the cell

Schwann Cells

In PNS, forms the myelin sheath

Nodes of Ranvier

Gaps between the myelin (unmyelinated regions)

Myelin Sheath

White fatty tissue (myelin) that insulates the axon

Axon Terminals

Connecting w/other neurons or tissue

What is the nerve impulse and how does it move along the axon?

Nerve impulse or action potential is a temporary reversal of electrical charge across the neuron’s membrane that propagates along the axon as a wave of depolarization.

It moves along the axon, the action potential starts at the cell body (trigger zone) if a threshold potential (around -55mV) is met. The depolarized state at one point on the axon triggers adjacent voltage-gated ion channels to open, causing the “wave” to move. The impulse travels in one direction only because the preceding segment is in a refractory period (depolarizing) and cannot fire again

How does nerve impulse transmission occur across the synapse?

Nerve impulse transmission occurs when the action potential triggers the release of the neurotransmitters from the presynaptic neuron. The neurotransmitters then cross the synaptic cleft and bind to receptors on the postsynaptic neuron, causing a response.

Explain which nerves are involved in a reflex arc

A reflex arc is a rapid, involuntary nerve pathway that produces an automatic response to a stimulus, typically involving sensory neurons, interneurons (in the spinal cord), and motor neurons