Nervous System And Action Potentials Flashcards by Natalia Stando

What is a neuron?

Cell of the nervous system specialised to generate and transmit electrical signals.

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What is a nerve?

bundle of axons in the peripheral nervous system

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What is a ganglia?

Collection of neural cell bodies outside of the CNS

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Simplest motor action of the peripheral nervous system is the ….. ……..

Reflex arc

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Sensory nerves in the PNS send signals to the …..

CNS

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Each type of sensory detector has a different cell structure. What is the sensory division in the PNS?

Vision, hearing, smell, taste and touch

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What is a dermatome

-area of skin innervated by the cutaneous branches of a single spinal nerve
-each nerve sends signals to a different part of the body, and the area of the skin that it covers is called a dermatome

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How do sensory and motor divisions work together?

SENSORY DIVISION:
-gathers info from the body and the environment, like touch, pain, temperature, or vision.
-sends these signals to the brain.

MOTOR DIVISION:
-brain processes sensory info, then motor division sends signals from the brain to muscles and glands
-tells them how to respond e.g. like moving your hand away from something hot.

INTEGRATION:
-happens when brain combines info from both divisions.
-e.g.if you touch something hot (sensory input), the brain quickly processes this and sends a signal through the motor division to make your muscles pull your hand away.
-sensory and motor divisions work together to help you react appropriately to your surroundings.

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In the knee-jerk reflex arc, the ……. neuron can directly connect to the ………. neuron in the spinal cord

Sensory, motor

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1.The brain has areas devoted to control the different functions of the ….

SNS has cells in the motor cortex that send signals to the ……… ………
ANS cells are located in the ……….. nuclei and send signals to the ……….. ………., ………, ………. ……… and …………….

PNS
Skeletal muscle
Visceral nuclei, smooth muscles, glands, cardiac muscle and adipocytes

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What two movements is the Somatic nervous system responsible for?

Voluntary movement and reflex arc

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What is the Somatic nervous system’s primary role and what part of the reflex is it?

-primary role= connect CNS to muscles, organs (inc. skin)
-motor (efferent) part of the reflex

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What is the Autonomic nervous system responsible for?

Innervates (supply a body part with nerves) cardiac and smooth muscles and glands.

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What is the Autonomic nervous system also known as?

Involuntary or visceral motor system

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What is the autonomic nervous system split into ?

Parasympathetic nerves and sympathetic nerves.

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Function of the frontal lobe

Executive functions, thinking, planning, organising and problem solving, emotions and behavioural control, personality

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Function of motor cortex

Movement

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Function of somatosensory cortex

Sensations

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Function of parietal lobe

Perception, making sense of the world, arithmetic, spelling

Functions of the occipital lobe

Vision

Function of temporal lobe

Memory, understanding, language

What are neuroglia (glial cells) and what cells are included within the group ?

-non-excitable cells of neural tissue that support, protect & insulate the neurons. -oligodendrocyte, astrocyte, Bergmann cells and microglia

What is the function of oligodendrocyte?

-support cell -forms myelin sheath around axons in CNS. -single oligodendrocyte can extend its processes to 50 axons, wrapping approx 1 um of myelin sheath around each axon.

What is the function of astrocytes?

-support cell -assists exchanges between blood capillaries & neurons. -20 - 40% of glia

What are bergmann cells?

Astrocytes in cerebellum

What are microglia cells and their function?

-support cell -free roaming -transform into phagocytes in areas of neural damage or inflammation in brain & spinal cord. -10 - 15% of cells in brain

How do multiple axons allow signal amplification?

By sending one signal to many receiving neurons or muscle cells

What does the structure of the spine protect?

Nerves of the spinal cord

What is the importance of the spinal cord?

-Involved in sensory and motor innervation of the entire body, inferior to the head -Provides a two way conduction pathway between the body and the brain -Major centre for reflexes

What is the thickness of the cell membrane?

6-8 nm

What type of molecules primarily make up the cell membrane?

Phospholipid molecules

What are the two main types of proteins important for electrical changes in the cell membrane?

Ion channels and pumps

What is the primary function of ion channels in the cell membrane?

Allow transport of ions through the non-conducting phospholipid membrane

What type of macromolecules are found in the cell membrane?

Proteins and glycoproteins

Fill in the blank: The cell membrane is an electrically non-conducting thin bilayer of _______.

phospholipid molecules

True or False: The cell membrane is a static structure.

False

What characteristic of the cell membrane allows for the transport of ions?

Presence of ion channels and pumps

What does it mean when ion channels are ligand (chemical) gated?

Open on ligand binding

What does it mean when ion channels are voltage gated?

Open on change in electrical charge

What does it mean when ion channels are mechanical?

Open when receptor changes shape

What does leakage in ion channels mean?

Always open

What is the approximate resting potential for nerve cells?

-60mV to -70mV ## Footnote The resting potential is the electrical charge difference across the membrane when the cell is not actively transmitting a signal.

What is the approximate resting potential for muscle cells?

-90mV

What is the state of gated channels at resting potential?

-Closed -Gated channels remain closed during the resting state, preventing ion flow.

What causes the negative charge inside the cell membrane?

-Greater ability of K+ to diffuse OUT than Na+ to flow IN -This differential permeability contributes to the membrane's resting potential.

What role does the sodium pump play in maintaining cell potential?

-Maintains concentration gradients -The sodium pump actively transports Na+ out of the cell and K+ into the cell, helping to maintain resting potential.

Ion activity at resting potential

What are graded potentials?

-Small changes in membrane potential that can be depolarising or hyperpolarising. -Graded potentials vary in size and can summate.

What happens when a graded potential exceeds the threshold potential?

It becomes an action potential and the neuron fires.

What is a trigger zone?

The first segment of the axon after it leaves the cell body.

What happens at resting potential?

-no ions move through voltage gated channels

What happens during depolarisation?

-when threshold of -55mV is reached, an action potential is generated -voltage-gated Na+ channels open (positive feedback effect) -Na+ ions flood into the cell, raising the membrane potential to about +30mV.

What happens during repolarisation?

-voltage-gated K+ channels open, K+ diffuse out of axon -After about 1ms, voltage-gated Na+ channels close and cannot reopen until the voltage returns to resting levels (-70mV). -this is called a refractory period.

What happens during hyperpolarisation?

-K+ channels slow to close so there’s a slight overshoot (Too many K+ diffuse out) -some K+ channels remain open and Na+ channels reset

Where does action potential conduction (APC) takes place?

-along the length of axon -between neurons- at a synapse

What structures contribute to action potential conduction (APC) along the axon?

-lon channels (depolarisation, repolarisation) -Myelin sheaths (Schwann cells in particular) -Nodes of Ranvier -Saltatory conduction

What are nodes of ranvier?

-gaps in a myelin sheath (between Schwann cells) of certain axons -where an action potential may be generated.

What are myelin sheaths?

-insulating coat of the cell membranes produced by Schwann cells (PNS) or oligodendrocytes (CNS) -Myelination is essential for rapid and accurate impulse conduction. -It saves space, by allowing many neurons to be bundled together.

Neurotransmitters in the CNS may be ………… or……………..on the post synaptic cell - signal integration.

-excitatory -inhibitory