Physiology Mock Exam: Quiz! MCQ

RBCs, or red blood cells, have a lifespan of approximately 120 days. These cells play a crucial role in transporting oxygen to various parts of the body. Over time, RBCs become damaged and less efficient, and are eventually removed from circulation by the spleen. The body constantly produces new RBCs to replace the old ones, maintaining a healthy balance. Therefore, the correct answer is 120 days.

Acetylcholine is the correct answer because it is the primary neurotransmitter released at the neuromuscular junction. When a nerve impulse reaches the neuromuscular junction, acetylcholine is released from the presynaptic neuron and binds to receptors on the postsynaptic membrane of the muscle cell. This binding triggers a series of events that ultimately lead to muscle contraction. Glutamate, adrenaline, and nor-adrenaline are neurotransmitters involved in other functions in the nervous system, but they are not typically released at the neuromuscular junction.

Serum is the component of blood that remains after the blood has clotted and the clot has been removed. It is similar to plasma, but it lacks fibrinogen and other coagulation factors. This means that serum does not have the ability to clot. Therefore, the correct answer is "Plasma with low fibrinogen and coagulation factors concentration."

When a person drinks 2L of iso-tonic fluid, it will cause an increase in extracellular fluid (ECF) volume. Iso-tonic fluid has the same concentration of solutes as the body's fluids, so when it is consumed, it is readily absorbed into the bloodstream. This leads to an increase in the volume of the ECF, which includes the fluid found outside the cells in the body. The increase in ECF volume helps to maintain proper hydration and balance electrolyte levels in the body.

Exocytosis is the correct answer because it refers to the process of big materials being expelled from the cell by fusing vesicles with the plasma membrane and releasing their contents to the exterior. Endocytosis, on the other hand, is the process of taking in materials into the cell by engulfing them with the plasma membrane. Pinocytosis is a type of endocytosis that involves the cell taking in fluids and dissolved substances. Therefore, only exocytosis involves the extrusion of big materials to the exterior of the cell through the plasma membrane.

During muscle contraction, calcium ions (Ca+2) increase inside the skeletal muscles. Calcium ions play a crucial role in muscle contraction by binding to the regulatory proteins troponin and tropomyosin, causing a conformational change that allows actin and myosin to interact and generate force. This interaction leads to the sliding of actin and myosin filaments, resulting in muscle contraction. Therefore, an increase in calcium ions inside the skeletal muscles is necessary for the initiation and regulation of muscle contraction.

When k+ channels open, repolarization occurs. Repolarization is the phase of an action potential where the membrane potential returns to its resting state after depolarization. This is achieved by the efflux of potassium ions (K+) out of the cell, which helps restore the negative charge inside the cell and bring the membrane potential back to its resting level. Repolarization is essential for allowing the cell to recover and be ready for the next action potential.

Increasing the concentration gradient across the membrane would increase the rate of O2 diffusion because a higher concentration difference would create a steeper gradient for O2 molecules to move from an area of higher concentration to an area of lower concentration. This would increase the driving force for diffusion and therefore increase the rate of O2 movement across the cell membrane.

Turtles do not have maternity instinct because they do not exhibit parental care towards their offspring. Unlike humans, birds, and pigs, turtles do not build nests, incubate their eggs, or provide any form of protection or care for their young. Instead, they lay their eggs in a hole in the sand and leave them to hatch and fend for themselves. This lack of maternal instinct sets turtles apart from the other creatures listed.

The immune system is not directly involved in maintaining homeostasis. While it plays a crucial role in defending the body against pathogens and foreign substances, its primary function is to protect the body from infections and diseases. Homeostasis, on the other hand, refers to the body's ability to regulate and maintain a stable internal environment, such as body temperature, pH levels, and fluid balance. The renal system helps regulate fluid and electrolyte balance, the circulatory system transports nutrients and oxygen, and the respiratory system regulates oxygen and carbon dioxide levels in the body, all of which are directly involved in maintaining homeostasis.

The gain of a control system represents the amplification or attenuation of the input signal. In this case, the first system has a higher gain of 4 compared to the second system's gain of 3. A higher gain means that the first system can amplify the input signal more effectively, resulting in a better correction of errors. Therefore, the correct answer is that the first system correction is better than the second system.

Bleeding is not a case of good positive feedback because it involves the loss of blood from the body, which is not beneficial. Positive feedback typically refers to a process that amplifies or reinforces a certain response or action, leading to a desired outcome. In the case of bleeding, it is a negative event that needs to be stopped or controlled, rather than being reinforced or amplified.

An increase in neutrophils is typically indicative of a bacterial infection. Neutrophils are a type of white blood cell that play a crucial role in the body's immune response to bacterial infections. When bacteria invade the body, neutrophils are recruited to the site of infection to help eliminate the bacteria. Therefore, an increase in neutrophils suggests that the body is actively fighting off a bacterial infection.

The resting membrane potential is the electrical potential difference across the cell membrane when the cell is at rest. It is primarily determined by the balance between the Na-K exchange and the permeability of the cell membrane to K+. The Na-K exchange works to maintain the concentration gradients of sodium and potassium ions across the membrane, while the permeability of the cell membrane to K+ allows for the movement of potassium ions out of the cell. The selectivity of the cell membrane also plays a role in determining the resting membrane potential by allowing certain ions to pass through more easily than others. However, the Na-Ca exchange, which is mentioned as the correct answer, does not play a direct role in the genesis of resting membrane potential.

Gamma globulin is not produced in the liver. It is a type of immunoglobulin that is produced by plasma cells in the lymph nodes and spleen. Albumin, fibrinogen, and alpha globulin are all proteins that are produced in the liver. Albumin is the most abundant protein in the blood and helps maintain osmotic pressure. Fibrinogen is involved in blood clotting, and alpha globulin is involved in transporting lipids and hormones.

Based on the given information, the patient's total body fluid is 60% of their body weight, which is 50 kg. Therefore, the total body fluid is 30 kg (50 kg x 0.60 = 30 kg). The intracellular fluid (ICS) is 40% of the body weight, which is 20 kg (50 kg x 0.40 = 20 kg). The remaining 10 kg is the extracellular fluid (ECF).

The total osmotic content is given as 9000 mosmolar. Since the osmolarity is the total osmotic content divided by the total body fluid, we can calculate it as follows:

Osmolarity = Total osmotic content / Total body fluid
Osmolarity = 9000 mosmolar / 30 kg
Osmolarity = 300 mosmolar

Therefore, the individual's osmolarity of body fluid would be 300 mosmolar.

When the membrane potential changes from +30 mV to -120 mV, it goes beyond the resting membrane potential of -90 mV, indicating hyperpolarization. Hyperpolarization occurs when the membrane potential becomes more negative than the resting potential, making it less likely for an action potential to be generated.

When the body is exposed to a hot environment, the rise in environmental temperature causes an increase in body temperature. In response to this, the body initiates sweating to cool itself down. The evaporation of sweat from the skin helps to lower the body temperature. The question states that the environmental temperature rises by 17 cc and the gain is 33. This means that the body temperature will increase by 33 cc. Therefore, the correct answer is "Normal +0.5", indicating that the body temperature will be the normal temperature plus 0.5 cc.

The osmolarity of a solution is determined by the number of particles present in the solution. In this case, the molarity of the 4% solution of NaCI is given as 680 mmol/L. Since NaCI dissociates into one Na+ ion and one Cl- ion, the number of particles in the solution is twice the molarity. Therefore, the osmolarity of the 4% solution is 680 x 2 = 1360 mOsm/L. Since the osmolarity is directly proportional to the molarity, the osmolarity of the 2% solution of NaCI will also be 680 mOsm/L.

A blood pH of 7.2 is indicative of acidosis because a normal blood pH range is 7.35-7.45. A pH of 7.2 is lower than the normal range, indicating an excess of acid in the blood. Acidosis can occur due to various reasons such as respiratory or metabolic disorders, kidney dysfunction, or excessive production of acids in the body. It is important to identify and treat acidosis to restore the acid-base balance in the body.

The hematocrit is a measure of the volume percentage of red blood cells in the total blood volume. In this case, the hematocrit is given as 40%. Assuming that the plasma volume is 3000, we can calculate the blood volume by dividing the plasma volume by (100 - hematocrit). So, the blood volume would be 3000 / (100 - 40) = 5000. Therefore, the blood volume of the patient is 5 liters.

The gain of a control system can be calculated by dividing the output by the input. In this case, since the control system corrects 90% of the changes, it means that the output is 90% of the input. Therefore, the gain can be expressed as 0.9/1. Simplifying this fraction gives us 27/3.

The last human instinct activated during the life of a human is maternity. This refers to the instinctual desire and ability to care for and protect one's offspring. While food and sex are also basic instincts, they can be present throughout a person's life. However, maternity specifically pertains to the instinctual behavior related to reproduction and nurturing of offspring, which typically occurs later in life during the childbearing years.

When active Na-K transport is inhibited, the cell volume will increase. This is because the Na-K pump plays a crucial role in maintaining cell volume by actively transporting Na+ out of the cell and K+ into the cell. When this transport is inhibited, the intracellular concentration of Na+ increases, causing an influx of water into the cell through osmosis. This influx of water leads to an increase in cell volume.

The neuromuscular transmission is the process by which a signal is transmitted from a motor neuron to a muscle fiber. It involves several steps, including the influx of calcium ions into the presynaptic neuron, the release of neurotransmitters into the synaptic cleft, and the release of calcium ions from the sarcoplasmic reticulum into the sarcoplasm. However, the increase in Na-K pump activity is not a step in the neuromuscular transmission process. The Na-K pump is responsible for maintaining the concentration gradients of sodium and potassium ions across the cell membrane, but it does not directly play a role in the transmission of signals between neurons and muscle fibers.

Facilitated diffusion is a type of passive transport where molecules move across a cell membrane with the help of specific transport proteins. This process does not require energy expenditure by the cell. The given answer, "Saturate at high solute concentration," is correct because facilitated diffusion can become saturated when the concentration of solute molecules is high. At high concentrations, all the transport proteins may be occupied, and the rate of diffusion will no longer increase even if the concentration gradient is further increased.

At inhibitory synapses, the opening of K+ gates is increased. This allows more K+ ions to leave the cell, leading to hyperpolarization. Hyperpolarization makes it more difficult for the neuron to reach the threshold level required to generate an action potential, effectively inhibiting the transmission of the signal. Increasing the K+ gates helps to maintain the inhibitory effect and prevent the generation of an action potential.

Reticulocytes are the correct answer because they are the immature red blood cells that are released from the bone marrow into the bloodstream. These cells still contain some remnants of ribosomes, giving them a reticulated or "net-like" appearance when viewed under a microscope. As they mature, these ribosomes are lost, and the reticulocytes develop into fully functional erythrocytes or red blood cells. Therefore, reticulocytes are the precursor cells that will eventually become mature red blood cells.

Iron deficiency does not lead to macrocytic anemia. Macrocytic anemia is characterized by larger than normal red blood cells, whereas iron deficiency anemia is characterized by smaller than normal red blood cells. Iron deficiency anemia leads to microcytic anemia.

When a stimulus is applied to a nerve cell, it causes a change in the membrane permeability to ions. This means that the cell's membrane becomes more permeable to ions, allowing them to flow in and out of the cell more easily. This change in ion permeability is crucial for generating electrical signals in the nerve cell and transmitting information. It allows ions such as sodium, potassium, and calcium to move across the membrane, which is essential for the proper functioning of the nerve cell.