biology C2.2

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function of dendrites

recieve signals from other neurons or sensory receptors

function of the axon

conducts electrical impulses away from the cell body

function of the cell body

contains nucleus and organelles; integrates incoming signals

define membrane potential

electrical potential difference across a cell membrane

define resting potential

membrane potential of a neuron when it is not sending a signal

mechanisms that create resting potential

sodium-potassium pump

membrane’s selective permeability

trapped negative ions inside the cell

voltage of resting potential

-70 mV

define nerve impulse

a wave of depolarisation that travels along a neuron

define action potential

Rapid change in membrane potential from negative to positive and back to negative.

correlation between conduction speed and axon diamter?

larger diameter —> faster conduction due to less resistance

myelinated fibers

salatroy conduction; impulses jump between nodes —> much faster

unmyelinated fiber

continuous conduction, slower

correlation between animaly size and condctuion speed

larger animals generally have alrger, often myelinated neurons; faster conduction

define synapse

junction where a neuron communicates with another neuron or effector cell

define synaptic gap

space between presynaptic and postsynaptic cells

define effector

cell thst responds to neural signals

examples of effector cells

muscle fibers, endocrine gland cells, exocrine gland cells

direction of signal flow across synapse

presynaptic —> postsynaptic

role of neurotransmitters

chemical messengers that transmit signals across synapses

what is the role of calcium?

chemical signal that triggers exocytosis of neurotransmitters

mechanism of synaptic transmission at presynatic cell

1. Action potential arrives → depolarization.

2. Voltage-gated Ca²⁺ channels open.

3. Ca²⁺ enters presynaptic terminal.

4. Ca²⁺ triggers vesicle fusion.

5. Neurotransmitter released via exocytosis.

6. Neurotransmitter diffuses across synaptic cleft.

mechanism at the postsynatic cell

1. Neurotransmitter diffuses across cleft.

2. Binds to receptor proteins.

3. Opens gated ion channels.

4. If threshold is reached → action potential generated.

5. Ions flow → excitatory postsynaptic potential (EPSP).

what is acetylcholine?

common neurotransmitter found in many synapses, including neuromuscular junctions in both vertebrates and invertebrates.

how is acetylcholine digested?

By the enzyme acetylcholinesterase, which breaks it into acetate and choline to stop the signal.