The threshold potential of the action potential of SA node is achieved due to the slow influx of calcium ions.

Pacemaker cells in the SA node are autorhythmic (can generate own electrical impulses without external simulation). This primarily corresponds to prepotential phase shown in inset (b), because that’s the phase, at the end of which, the threshold for the next action potential is achieved.

Pacemaker cells in the SA node are autorhythmic (can generate own electrical impulses without external simulation). This primarily corresponds to the rapid depolarization phase shown in inset (b).

The heart's electrical conduction pathway begins at the sinoatrial (SA) node and finishes with the Purkinje fibers.

For inset (b), it’s possible that multiple action potentials can happen before one contraction cycle (or 1 peak in the contraction plot) is complete.

Skeletal muscle has a slightly higher magnitude for its resting potential than the cardiac muscle

For inset (a), the duration of contraction is larger than the duration of excitation.

For inset (a), it’s possible that multiple action potentials can happen before one contraction cycle (or 1 peak in the contraction plot) is complete.

The resting potential of the cardiac muscle has a higher magnitude than the resting potential of the neuron

Sodium ions play no role in the depolarization of the action potential shown in inset (b).

Cardiac action potentials have a plateau phase, while neuronal action potentials do not.

The action potential of a neuron is considerably shorter in duration than the action potential of the cardiac muscle

The refractory period in the action potential shown in inset (a) is due to the efflux of potassium ions and an influx of calcium ions.

The structure labeled

"Troponin" is shown situated directly on the myosin heads,

facilitating their attachment to actin.

The

"I band" is depicted as a region containing the Z line and portions

of the thick filaments extending from Z line.

“H zone" represents the region of

the sarcomere containing only thick filaments and the M line

The thin filaments are shown to be

composed solely of actin subunits.

Each individual myosin molecule

illustrated possesses distinct "Actin-binding sites" and an

"ATP-binding site", both located on the heads.

Thick filaments consist of bundled myosin

molecules where the "Heads" project outwards, and these heads are

connected to the myosin "Tail" via a "Flexible hinge

region".

The type of muscle involved in the modulation of blood vessels diameter (shown in (c)), is (2) in inset (b). When someone is running vasoconstriction happens for thermoregulation.

When someone is running, the calf muscles in the legs are likely to belong to motor unit 2.

When someone is running, the heart rate will be faster since there will be an increase in frequency of the heart’s contraction cycle (a.k.a cardiac cycle).

When someone is running, the calf muscles in the legs are likely belonging to motor unit 1.

While running, the heart, our body’s muscular pump, will be pumping faster and hence the heart rate will be slower.

The type of muscle involved in the modulation of blood vessels diameter (shown in (c)), is (2) in inset (b). When someone exercises, vasodilation happens for thermoregulation.

The resting membrane potential for all

three tissue types shown is identical and corresponds exactly to 0 mV before

stimulation.

The structure called

‘Myelin’

encloses the

axon, which is responsible for passing signals from the neuron's cell body

towards the neuromuscular junction.

The membrane potential at the peak of the

action potential approaches closer to the equilibrium potential of Na⁺, as Na⁺

permeability is highest at that point.

The sodium-potassium pump (Na⁺/K⁺ ATPase)

is responsible for returning the membrane to resting potential post hyperpolarization.

The repolarization phase is primarily due

to the opening of voltage-gated Na⁺ channels and the influx of Na⁺ ions into

the cell.

Hyperpolarization is only dependent on

the inactivation loop of sodium channels, which allows excess K⁺ to exit the

cell beyond the resting potential level.

During the absolute refractory period,

another action potential can be generated, but only with a larger-than-normal

stimulus.

The protein labeled X is

likely a voltage gated sodium channel

protein.

The resting membrane potential arises in

the first place due to the presence of cell membrane made of phospholipid

bilayer.

The protein labeled X is

likely a potassium leak channel protein, contributing to the movement of K⁺

down its concentration gradient.

The

axon of the neuron

is

generally much longer in length than dendrites.

The resting membrane potential arises in

the first place due to the presence of cell membrane that has a monolayer of

phospholipids.

Parasympathetic

stimulation of the heart decreases cardiac output, conserving energy during

restful states.

Parasympathetic

activation causes bronchial dilation to facilitate deep, relaxed breathing

during rest-and-digest states.

The

sympathetic nervous system promotes urinary bladder contraction to expel waste

rapidly during emergencies.

Parasympathetic

input enhances digestion by increasing peristalsis and enzyme secretion in the

gastrointestinal tract.

As the person eats the pizza, digestive enzymes are secreted to help break down the food, and the endocrine system releases hormones that signal the release of these enzymes. However, signaling by the endocrine system is generally slower and less specific than signaling by the nervous system.