Physio presentation 4

What is the difference between the central and peripheral nervous systems?

Central nervous system: brain and spinal cord

Peripheral nervous system: everything else

PNS and CNS communicate via nerves that send sensory and motor information

What are the four basic structures in a neuron?

The soma, the dendrites, axon, and terminal buttons.

What does the soma contain?

Nucleus and most organelles of the neuron cell.

What are the dendrites?

Branched structures that are attached to the soma and receive messages from other neurons.

What is the axon?

A long, slender projection that transmits electrical impulses away from the soma to other neurons or muscles.

What are the terminal buttons?

Extensions of the axon that receive the electrical message and convert it into a chemical signal to transmit across the synapse.

Cell membrane, cytoskeleton, cytoplasm

components of the cell that help maintain its structure and facilitate communication between the cell and its environment.

Nucleus, endoplasmic reticulum, Golgi apparatus, and mitochondria

specialized structures within a cell that perform specific functions, such as energy production, protein synthesis, and waste processing.

What is the function of supporting cells in the CNS?

Supporting cells in the CNS, also known as glial cells, provide structural support, protect neurons, and facilitate communication between them, playing crucial roles in maintaining homeostasis and forming myelin.

What are the supporting cells in the CNS?

astrocytes, oligodendrocytes, and microglia

What are Schwann cells?

Supporting cells in the peripheral nervous system that produce myelin and aid in the regeneration of damaged nerves.

What does the Blood-Brain barrier do?

The Blood-Brain barrier protects the brain by selectively allowing certain substances to pass while blocking others, thus maintaining a stable environment for neural function.

What is the area postrema and why is it important?

The place in the brain responsible for vomiting out poison and more permeable to toxins, allowing the body to respond quickly to harmful substances.

What is the neural communication involved withdrawal reflex?

The neural communication involved in the withdrawal reflex is a rapid, involuntary response to a painful stimulus. It involves sensory neurons transmitting signals to the spinal cord, which then activates motor neurons to initiate a quick withdrawal of the affected body part.

How can withdrawal reflex be inhibited?

The withdrawal reflex can be inhibited by higher brain centers that exert control over spinal reflexes, allowing for voluntary movement and the ability to override the reflex response.

What is the electrical potential in resting potential?

The electrical potential in resting potential refers to the difference in charge across the neuronal membrane when the neuron is not actively firing, typically around -70 mV. This state is maintained by ion channels and the sodium-potassium pump, allowing the neuron to be ready for action potentials.

What is an action potential?

An action potential is a rapid and temporary change in the electrical potential across a neuron's membrane, resulting in the propagation of an electrical signal along the neuron. It occurs when the membrane depolarizes to a threshold level, allowing sodium ions to rush in, followed by repolarization as potassium ions exit.

What do diffusion, electrostatic pressure, and the sodium potassium pump do to create membrane potential?

They regulate ion distribution and movement across the membrane, establishing the resting membrane potential by balancing concentrations of sodium and potassium ions.

What do the ions do in action potential?

Once the threshold of excitation is reached, the sodium gates open and sodium enters the neuron, causing depolarization, followed by potassium gates opening to allow potassium to exit, resulting in repolarization.

What happens during the propagation of the action potential?

During the action potential, a rapid depolarization occurs as sodium ions flood into the neuron, followed by repolarization as potassium ions flow out, restoring the membrane potential.

What are the structures of the presynaptic cells?

They include the axon terminal, synaptic vesicles containing neurotransmitters, and the presynaptic membrane that interfaces with the postsynaptic cell.

How does neurotransmitter release work?

Neurotransmitter release occurs when an action potential reaches the axon terminal, triggering the influx of calcium ions, which causes synaptic vesicles to fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.

Ionotropic receptors

Open ion channels in direct response to the binding of a ligand

Metabotropic receptors

Indirectly open ion channels using G proteins, can also activate a second messenger system that goes to the nucleus or other parts of the cell, or turn genes on or off by beginning or ending production of certain proteins

What does EPSP do in postsynaptic cells?

EPSP is the depolarization that comes from adding sodium or calcium ions into the cell. Calcium can also bind with enzymes in the dendrites

What is an IPSP in postsynaptic cells?

the hyperpolarization when potassium ions leave or chloride ions enter

What happens in reuptake and enzyme deactivation?

The postsyaptic potentials are ended by removing a neurotransmitter by reuptake or deactivation of the enzymes

What happens when the depolarization gets too much?

Action potential fired

What do postsynaptic receptors do?

Located on the postsynaptic membrane, and relay a message to the postsynaptic cell. Can be mono or ionotropic

What are autoreceptors?

In the presynaptic membrane and regulate the amount of neurotransmitter released

Name other synapses

Axoaxonic, dendrodendritic synapses and gap junctions

What are examples of nonsynaptic communication?

Hormones and neuromodulators