Drgawad Mid-module Exam - Physiology

All of the substances mentioned in the question, including vitamin K, O2, and CO2, can pass through the lipid bilayer by simple diffusion. The lipid bilayer is composed of hydrophobic tails that allow nonpolar molecules, such as gases like O2 and CO2, to easily pass through. Additionally, lipid-soluble molecules like vitamin K can also pass through the lipid bilayer. Therefore, none of the substances mentioned are unable to pass through the lipid bilayer by this mechanism.

High resistant protein channels decrease the rate of diffusion through a membrane because they act as barriers and restrict the movement of molecules across the membrane. These protein channels are designed to be selective, allowing only specific molecules to pass through while blocking others. This selective nature of high resistant protein channels reduces the overall rate of diffusion by limiting the number of molecules that can cross the membrane.

Facilitated diffusion refers to the process by which large molecules are transported across a cell membrane with the help of carrier proteins. Unlike simple diffusion, facilitated diffusion requires the presence of a concentration gradient, meaning that the molecules move from an area of higher concentration to an area of lower concentration. In this case, the correct answer states that facilitated diffusion involves the transport of large molecules by a carrier protein, and this transport occurs along a concentration gradient.

Osmotic pressure is formed at the concentrated side. This is because osmosis is the movement of solvent molecules from an area of lower solute concentration to an area of higher solute concentration, through a semipermeable membrane. The osmotic pressure is the pressure required to prevent the flow of solvent molecules through the membrane. Therefore, it is formed at the concentrated side where there is a higher solute concentration.

The correct answer is that the normal resting membrane potential is due to the selective permeability of healthy membranes. This means that the membranes of cells allow certain ions to pass through more easily than others, creating a separation of charge across the membrane. This separation of charge is what creates the electrical potential difference across the membrane, which is important for various cellular functions such as nerve impulse transmission and muscle contraction.

A hypertonic solution leads to cell shrinkage because it has a higher solute concentration compared to the cell's cytoplasm. This causes water to move out of the cell through osmosis, leading to a decrease in cell volume and shrinkage. In a hypertonic solution, the cell loses water to the surrounding environment, causing it to shrink.

Childbirth is an example of positive feedback vicious mechanism because it involves a cycle where the initial stimulus (contractions) leads to a response (more contractions) that intensifies the stimulus, resulting in a continuous and escalating process until the baby is born. The release of oxytocin during contractions stimulates more contractions, creating a self-reinforcing loop. This positive feedback mechanism ensures the completion of the childbirth process by continually increasing the strength and frequency of contractions.

Osmotic pressure is the correct answer because it refers to the pressure needed in a concentrated solution to prevent water movement from the diluted side. Osmosis is the process by which water moves across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration. Osmotic pressure is the force required to stop this movement and maintain equilibrium between the two sides of the membrane.

The normal osmolality of the extracellular and intracellular fluids is 300 milliosm/L. Osmolality refers to the concentration of solutes in a solution, and it is an important measure of the body's fluid balance. The human body strives to maintain a constant osmolality to ensure proper functioning of cells and organs. A normal osmolality of 300 milliosm/L indicates a balanced distribution of solutes inside and outside the cells, allowing for optimal cell function and overall fluid balance.

The correct answer is CO2 feedback mechanism. Negative feedback mechanisms are regulatory processes that work to maintain homeostasis by reversing any changes from the set point. In the case of CO2 feedback mechanism, an increase in CO2 levels in the body triggers a response to decrease CO2 levels, restoring balance. This is an example of negative feedback because it opposes the initial change and brings the system back to its original state. Childbirth and hemostasis do not involve negative feedback mechanisms.

The largest proportion of body water is present in cells. Cells contain a high amount of water, which is essential for their normal functioning. The water inside cells helps in maintaining their shape, transporting nutrients and waste products, and facilitating various biochemical reactions. The other options, such as blood, interstitial fluid, and transcellular fluid, also contain water but in smaller proportions compared to cells.

Osmosis is the correct answer because it refers to the movement of water from an area of low solute concentration to an area of high solute concentration. This movement occurs across a semi-permeable membrane, allowing water molecules to pass through while preventing the solute molecules from doing so. Osmosis is driven by the difference in solute concentration, and the movement continues until equilibrium is reached.

Secondary active transport does not require ATP directly for the transportation of molecules. Instead, it utilizes the energy stored in the electrochemical gradient established by primary active transport, which does require ATP. In secondary active transport, the movement of one molecule down its concentration gradient is coupled with the movement of another molecule against its concentration gradient. This coupling allows the transport of the second molecule to occur without the direct expenditure of ATP.

A large surface area increases simple diffusion because it provides more space for molecules to move across the membrane. This allows for a greater number of molecules to pass through the membrane in a given amount of time, increasing the rate of diffusion.

Acetylcholine is considered an active ligand because it is a neurotransmitter that binds to specific receptors on the postsynaptic membrane, leading to a physiological response. It acts as a chemical messenger in the nervous system, transmitting signals between nerve cells and regulating various functions such as muscle contraction, heart rate, and memory. In contrast, Na ions, K ions, and ATP are not ligands but rather ions or molecules involved in cellular processes.

Filtration is the movement of water from side to side secondary to hydrostatic pressure. In this process, water is forced through a membrane or porous material, allowing the passage of smaller particles while blocking larger ones. This movement occurs due to the pressure difference on either side of the membrane. Osmosis, diffusion, and pinocytosis are different processes that involve the movement of substances across a membrane, but they do not specifically involve the movement of water from side to side secondary to hydrostatic pressure.

The correct answer is receptor, center, effector. In a reflex arc, the receptor detects a stimulus and sends a signal to the center (usually the spinal cord or brain) through the afferent pathway. The center then processes the information and sends a signal through the efferent pathway to the effector, which is a muscle or gland that carries out the response to the stimulus.

The Na K pump is important for normal excitability of a nerve because it maintains the concentration gradients of sodium and potassium ions across the cell membrane. This pump actively transports three sodium ions out of the cell and two potassium ions into the cell, against their concentration gradients. This creates a higher concentration of sodium ions outside the cell and a higher concentration of potassium ions inside the cell, which is necessary for generating action potentials and conducting nerve impulses. Therefore, the correct answer is that the Na K pump is important for normal excitability of a nerve.

Saline 0.9% is not related to hypertonic solutions because it is an isotonic solution. Hypertonic solutions have a higher solute concentration than that in the cell, causing the cell to shrink. However, saline 0.9% has the same solute concentration as that in the cell, resulting in no net movement of water and maintaining cell size. Therefore, saline 0.9% does not cause cell shrinkage and is not related to hypertonic solutions.

Osmolaity is the correct answer because it refers to the concentration of osmoles per kilogram of solvent. Osmolaity is a measure of the total solute concentration in a solution and is commonly used in medical and physiological applications to assess the osmotic balance in the body. Osmolaity is different from osmolarity, which measures the concentration of osmoles per liter of solution. Osmotic pressure is a related concept, but it specifically refers to the pressure exerted by the movement of solvent molecules across a semipermeable membrane to equalize the concentration of solutes on both sides.

Calcium (Ca) ions have the highest concentration in the body compared to sodium (Na), potassium (K), and chloride (Cl) ions. Calcium plays a crucial role in various physiological processes such as muscle contraction, nerve function, blood clotting, and bone formation. It is also involved in maintaining the balance of other ions in the body. Therefore, the high concentration of calcium ions in the body is essential for overall health and proper functioning.

Glucose transport can occur through various mechanisms, including facilitated diffusion, active transport, and secondary active transport. Pinocytosis, which is the process of engulfing extracellular fluid and particles, is not a mechanism by which glucose is transported into cells. Instead, glucose is typically transported through carrier proteins or channels, either by facilitated diffusion or active transport. Therefore, the statement "it may be by pinocytosis" is false.