Membrane Potential
Differentiate between gap junctions, tight junctions and desmosomes
Gap junctions: Channels that allow direct cell-to-cell communication.
Tight junctions: Seal cells together to prevent passage.
Desmosomes: Anchor cells together.
True or False: The somatic nervous system can be both excitatory and inhibitory.
False – it is only excitatory (always triggers muscle contraction).
What is the function of the T-tubules in cardiac muscle?
They carry the action potential deep into the muscle fiber to trigger calcium release.
What is the primary difference between the left and right sides of the heart?
The left side pumps oxygenated blood to the body, the right side pumps deoxygenated blood to the lungs.
his part of the nephron is responsible for the majority of reabsorption, including glucose, amino acids, and sodium.
What is the proximal convoluted tubule?
Action vs Graded potential
Action potential: All-or-nothing electrical signal that travels down the axon.
Graded potential: Small, local change in membrane potential; strength varies with stimulus.
What neurotransmitter is used in both the autonomic but not somatic system
Norepinephrine
What causes tropomyosin to move off the myosin binding site on actin?
Calcium binds to troponin, causing a shape change that shifts tropomyosin.
What valve closing makes the “lub” sound?
The atrioventricular (AV) valves (tricuspid and bicuspid/mitral).
This pressure inside the glomerular capillaries drives filtration into Bowman’s capsule.
What is glomerular capillary hydrostatic pressure?
Explain the main difference between tonicity and Osmolarity when determining water movement
Osmolarity includes all solute particles, both penetrating and non-penetrating .
Tonicity only considers non-penetrating solutes.
Which autonomic division has short preganglionic and long postganglionic fibers?
Sympathetic nervous system
How does the myosin head detach from the actin binding site at the end of the cycle?
ATP binds to myosin, causing it to release from actin.
Very briefly list the electrical conduction pathway of the heart.
SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers
This hormone increases water reabsorption by inserting aquaporins into the collecting duct.
Antidiuretic hormone (ADH) or vasopressin?
Explain the main factors responsible for the negative membrane potential.
The Na⁺/K⁺ pump maintains the imbalance (3 Na⁺ out, 2 K⁺ in).
Because more K⁺ leaks out of the cell than Na⁺ leaks in.
Briefly differentiate between the somatic and autonomic nervous systems.
Somatic is voluntary, targets skeletal muscles.
Autonomic is involuntary, targets cardiac muscle, smooth muscle, and glands.
What is a motor unit?
One motor neuron and all the muscle fibers it innervates
What is the formula for Cardiac Output
Stroke Volume x Heart Rate
The countercurrent multiplier system creates a high osmolarity gradient in this part of the kidney to enable water reabsorption.
What is the renal medulla?
Differentiate between temporal summation vs spatial summation
Temporal summation: One neuron fires repeatedly over time to trigger an action potential.
Spatial summation: Multiple neurons fire at the same time to combine signals at the postsynaptic membrane.
What is the specific role of calcium in the neuromuscular junction?
It triggers ACh release from the presynaptic neuron by allowing vesicle fusion.
Briefly explain twitch summation and tetanus.
Twitch summation is increased tension from repeated stimuli.
Tetanus is a sustained contraction when stimuli are so frequent that the muscle doesn't relax.
What does the QRS complex represent on the EKG?
It represents ventricular depolarization.
This specialized structure in the nephron regulates blood pressure and GFR by releasing renin in response to low perfusion.
What is the juxtaglomerular apparatus?