During ventricular systole, both the mitral and tricuspid valves are open to allow blood flow into the ventricles.
Correct Answer
False
During ventricular systole, the ventricles contract, and the mitral (bicuspid) and tricuspid valves close to prevent blood from flowing back into the atria.
Question 2
The 'dub' sound of the heart, S2, is caused by the closure of the aortic and pulmonary valves.
Correct Answer
True
The second heart sound (S2), or 'dub', marks the beginning of ventricular diastole and is produced by the simultaneous closure of the semilunar valves (aortic and pulmonary valves).
Question 3
Isovolumetric relaxation occurs when the ventricles are relaxing, and all four heart valves are closed.
Correct Answer
True
Isovolumetric relaxation is a phase of ventricular diastole where ventricular pressure drops, but no blood enters or leaves the ventricles because both the atrioventricular and semilunar valves are closed.
Question 4
The dicrotic notch on an aortic pressure tracing represents the closure of the tricuspid valve.
Correct Answer
False
The dicrotic notch is a small dip in the aortic pressure tracing that occurs due to the brief backflow of blood against the closed aortic valve, marking its closure.
Question 5
Oxygen primarily travels in the blood dissolved directly in the plasma.
Correct Answer
False
While a small amount of oxygen is dissolved in plasma, the vast majority (approximately 98.5%) is transported bound to hemoglobin within red blood cells.
Question 6
Carbon dioxide is transported in the blood mainly as bicarbonate ions.
Correct Answer
True
Approximately 70% of carbon dioxide is transported in the blood as bicarbonate ions (HCO3-), which are formed within red blood cells and then released into the plasma.
Question 7
An increase in blood PCO2 causes a decrease in blood pH, leading to increased oxygen affinity for hemoglobin.
Correct Answer
False
An increase in blood PCO2 causes a decrease in blood pH (acidosis), which *reduces* hemoglobin's affinity for oxygen, facilitating oxygen release to tissues (Bohr effect).
Question 8
Alveolar gas exchange efficiency is increased when the partial pressure gradient for oxygen between the alveoli and pulmonary capillaries is high.
Correct Answer
True
Gas exchange across the alveolar and capillary membranes is driven by partial pressure gradients. A larger gradient for oxygen means a faster and more efficient diffusion of oxygen into the blood.
Question 9
Glomerular filtration is a selective process where proteins and blood cells are freely filtered from the blood into Bowman's capsule.
Correct Answer
False
Glomerular filtration is *not* selective for proteins and blood cells; the filtration barrier normally prevents large proteins and all blood cells from entering Bowman's capsule.
Question 10
The primary driving force for glomerular filtration is the hydrostatic pressure in the glomerular capillaries.
Correct Answer
True
The high hydrostatic pressure within the glomerular capillaries forces fluid and small solutes out of the blood and into Bowman's capsule, initiating the filtration process.
Question 11
Reabsorption in the renal tubules involves the movement of substances from the tubular lumen back into the peritubular capillaries.
Correct Answer
True
Reabsorption is the process by which essential substances like water, ions, and nutrients are selectively moved from the filtrate within the renal tubules back into the bloodstream via the peritubular capillaries.
Question 12
Vasoconstriction of the afferent arteriole to the glomerulus would increase the glomerular filtration rate (GFR).
Correct Answer
False
Vasoconstriction of the afferent arteriole reduces blood flow into the glomerulus, which decreases glomerular hydrostatic pressure and consequently *decreases* the glomerular filtration rate (GFR).
Question 13
Neurotransmitters are released from the postsynaptic neuron and bind to receptors on the presynaptic neuron.
Correct Answer
False
Neurotransmitters are released from the *presynaptic* neuron into the synaptic cleft and bind to specific receptors on the *postsynaptic* neuron to transmit a signal.
Question 14
An inhibitory postsynaptic potential (IPSP) makes the postsynaptic neuron's membrane potential more negative, making it less likely to fire an action potential.
Correct Answer
True
An IPSP hyperpolarizes the postsynaptic membrane or stabilizes it at the resting potential, moving it further from the threshold needed to generate an action potential.
Question 15
Myelination of an axon increases the speed of action potential conduction by allowing continuous propagation along the entire axon membrane.
Correct Answer
False
Myelination increases the speed of action potential conduction through saltatory conduction, where the action potential 'jumps' between nodes of Ranvier, rather than propagating continuously along the entire membrane.
Question 16
The opening of voltage-gated sodium channels is responsible for the depolarization phase of an action potential.
Correct Answer
True
During the depolarization phase of an action potential, voltage-gated sodium channels open, allowing a rapid influx of positively charged sodium ions into the neuron, making the membrane potential more positive.
Question 17
In a negative feedback loop, an increase in the output of a hormone leads to a further increase in its own production.
Correct Answer
False
In a negative feedback loop, an increase in the output of a hormone or its effects *inhibits* its own further production, helping to maintain homeostasis by returning the system to a set point.
Question 18
The regulation of blood glucose by insulin and glucagon is an example of an antagonistic hormone interaction.
Correct Answer
True
Insulin and glucagon have opposing effects on blood glucose levels; insulin lowers it, while glucagon raises it, demonstrating an antagonistic interaction.
Question 19
A positive feedback loop is characterized by a response that amplifies the initial stimulus, moving the system further from its set point.
Correct Answer
True
Positive feedback loops enhance or intensify the original stimulus, leading to a greater response, such as the release of oxytocin during childbirth or the process of blood clotting.
Question 20
Parathyroid hormone (PTH) release is directly stimulated by high blood calcium levels.
Correct Answer
False
Parathyroid hormone (PTH) release is directly stimulated by *low* blood calcium levels, as its primary function is to increase blood calcium concentrations.
Question 21
Homeostasis refers to the body's ability to maintain a relatively stable internal environment despite external changes.
Correct Answer
True
Homeostasis is the physiological process by which the body actively maintains a stable equilibrium within its internal environment, despite fluctuations in external conditions.
Question 22
The effector in a homeostatic control system is the component that detects the deviation from the set point.
Correct Answer
False
The effector is the component that *carries out the response* to correct the deviation from the set point. The receptor (or sensor) is the component that detects the deviation.