IB HL C2.1 Chemical Signalling Part 1

What is a hormone?

• A chemical substance produced by a gland and carried by the blood

• A type of neurotransmitter

• A protein released by cells

• A gas that transmits signals

How do neurotransmitters transmit signals?

• By diffusing through the air

• By binding to receptors inside cells

• Through the bloodstream

• Across the synaptic cleft from the presynaptic neurone to the post-synaptic neurone

What are cytokines?

• Proteins released by nearly all cells in the human body

• A type of neurotransmitter

• Chemicals that transmit signals across the synaptic cleft

• Hormones that interact with cells by binding to receptors

What is the role of calcium ions (Ca2+) in the human body?

• Involved in many signaling pathways, such as muscle contraction

• Allows hormones to cross cell membranes

• Triggers the movement of vesicles in cells

• Initiates the release of neurotransmitters into the synapse

How do amines and proteins (hydrophilic hormones) function?

• By binding to external membrane receptors

• By crossing phospholipid bilayers easily

• By diffusing through the cytoplasm

• By binding to receptors inside cells

Which neurotransmitter also acts as a hormone?

• Cytokines

• Calcium ions

• Epinephrine (adrenaline)

• Acetylcholine

What is the average distance for neurotransmitters to diffuse from the presynaptic to the post synaptic membrane?

• 20 nanometres

• 100 micrometers

• 5 centimeters

• 1 millimeter

How do steroid hormones (hydrophobic) interact with target cells?

• By diffusing through the bloodstream

• By crossing cell membranes and binding to receptors inside cells

• By triggering vesicle release

• By binding to external membrane receptors

What is the main difference between neurotransmitters and hormones in terms of effect?

• Neurotransmitters have a localised effect, while hormones may have a more distant effect

• Hormones have a localised effect, while neurotransmitters may have a more distant effect

• Both have a distant effect

• Both have a localised effect

How do cytokines interact with cells?

• By triggering muscle contraction

• By diffusing through the bloodstream

• By entering the cytoplasm of the cell

• By binding to receptors on the cell surface membrane