أسئلة فسيولوجي على ملف الـ MCQ Notes
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Questions and Answers

What characterizes osmolarity?

  • It only applies to intracellular solutions.
  • It is a measure of the diffusion rate of particles.
  • It is measured in osmol/L. (correct)
  • It depends on the type of membrane present.

    • Which statement accurately describes isotonic solutions?

  • They have a lower concentration than plasma.
  • They cause cells to shrink.
  • They do not affect cell volume.
  • They have a concentration of 0.9% NaCl. (correct)

    • What is the primary function of the Na+-K+ ATPase pump?

  • To facilitate passive transport of glucose.
  • To establish the Na concentration gradient. (correct)
  • To facilitate the movement of calcium into the cell.
  • To transport potassium ions out of the cell.

    • In secondary active transport, energy is obtained from which source?

    <p>The sodium concentration gradient.</p> Signup and view all the answers

    What is the ratio of preganglionic fibers to postganglionic fibers in the sympathetic nervous system?

    <p>1:32</p> Signup and view all the answers

    How do cotransport and counter-transport differ in their mechanisms?

    <p>Cotransport moves solutes in opposite directions.</p> Signup and view all the answers

    Which structure is primarily responsible for the relay of sympathetic fibers to the head and neck?

    <p>Superior cervical ganglia</p> Signup and view all the answers

    What occurs during the contraction of the dilator pupillae muscle?

    <p>Mydriasis (pupil dilatation)</p> Signup and view all the answers

    What is one example of receptor-mediated endocytosis?

    <p>Uptake of iron and cholesterol.</p> Signup and view all the answers

    Which of the following is NOT a sign of Horner syndrome?

    <p>Tachycardia</p> Signup and view all the answers

    What is the main purpose of the tight junctions in cells?

    <p>To connect cells and maintain structural stability.</p> Signup and view all the answers

    What indicates the stage of response in Earl Sutherland's cell signaling model?

    <p>Reception</p> Signup and view all the answers

    What is the primary result of a lesion in the Tl and T2 segments related to sympathetic supply?

    <p>Horner syndrome</p> Signup and view all the answers

    How does the parasympathetic nervous system's fiber ratio differ from the sympathetic nervous system?

    <p>1:2</p> Signup and view all the answers

    Which of the following describes the structure of sympathetic ganglia?

    <p>Short preganglionic and long postganglionic fibers</p> Signup and view all the answers

    What effects are associated with the relaxation of the ciliary muscle?

    <p>Decreased lens convexity</p> Signup and view all the answers

    What is the primary role of choline acetyltransferase (CAT) enzyme?

    <p>Synthesis of acetylcholine</p> Signup and view all the answers

    Which type of receptor is primarily involved in the stimulation of smooth muscles and secretory glands?

    <p>Muscarinic receptors</p> Signup and view all the answers

    What happens when acetylcholine binds to muscarinic receptors?

    <p>Depolarization occurs through Na and Ca influx</p> Signup and view all the answers

    How is acetylcholine primarily hydrolyzed in the body?

    <p>By choline-esterase enzyme</p> Signup and view all the answers

    What is the effect of large doses of nicotine on nicotinic receptors?

    <p>Inhibition of neuronal nicotinic receptors</p> Signup and view all the answers

    Which neurotransmitter is primarily associated with the sympathetic nervous system?

    <p>Noradrenaline</p> Signup and view all the answers

    What is the function of cholinesterases in relation to acetylcholine?

    <p>Keep the action localized</p> Signup and view all the answers

    Where are adrenaline and noradrenaline stored in the adrenal medulla?

    <p>In vesicles within chromaffin cells</p> Signup and view all the answers

    What characterizes primary hypokalemic periodic paralysis?

    <p>Recurrent attacks of muscle weakness</p> Signup and view all the answers

    What is a defining feature of C type nerve fibers?

    <p>Slow conduction speed of 0.5 - 2 m/sec</p> Signup and view all the answers

    Which conduction type is associated with myelinated nerve fibers?

    <p>Saltatory conduction</p> Signup and view all the answers

    What occurs during the resting state of a nerve fiber regarding energy?

    <p>Nerve fiber spends energy to maintain RMP</p> Signup and view all the answers

    What phase of thermal changes occurs due to the generation and propagation of nerve impulse?

    <p>Initial heat</p> Signup and view all the answers

    What is the relationship between myelin sheath thickness and conduction velocity?

    <p>Increased thickness increases conduction velocity</p> Signup and view all the answers

    Which of the following correctly describes the metabolic reaction changes during nerve impulse passage?

    <p>Increases to about double the resting state</p> Signup and view all the answers

    What would be an effect of local anesthetics on nerve fibers?

    <p>Decreased sensitivity of C fibers</p> Signup and view all the answers

    What happens to blood flow if the radius of a blood vessel is reduced to half its original size?

    <p>The flow decreases to one-sixteenth of its original value.</p> Signup and view all the answers

    How is resistance affected when blood viscosity increases?

    <p>Resistance increases and blood flow decreases.</p> Signup and view all the answers

    Which of the following describes the conditions for laminar blood flow?

    <p>Reynold number less than 2000.</p> Signup and view all the answers

    In Poiseuille's equation, how does the resistance focus on vessel radius?

    <p>Resistance is inversely proportional to the fourth power of the radius.</p> Signup and view all the answers

    Which factor does NOT contribute to increased blood viscosity?

    <p>Decrease in blood flow velocity.</p> Signup and view all the answers

    Which statement about turbulent blood flow is incorrect?

    <p>It occurs when blood viscosity is high.</p> Signup and view all the answers

    What is the relationship between blood flow and perfusion pressure?

    <p>Blood flow is directly proportional to perfusion pressure.</p> Signup and view all the answers

    Which of the following statements about arteriolar diameter control is true?

    <p>It is influenced by both nervous and chemical signals.</p> Signup and view all the answers

    What effect does sympathetic tone have on blood vessels?

    <p>Maintains normal arterial blood pressure</p> Signup and view all the answers

    What is the effect of vagotomy on heart rate?

    <p>Increases heart rate from 70 to 120 beat/min</p> Signup and view all the answers

    What is a characteristic of chemical synapses?

    <p>Show fatigue during stimulation</p> Signup and view all the answers

    What effect does neostigmine have on cholinesterase?

    <p>Blocks the action of cholinesterase</p> Signup and view all the answers

    Which of the following actions is associated with muscarinic action of acetylcholine?

    <p>Resistance to fatigue</p> Signup and view all the answers

    What is a consequence of sympathetic discharge in hot weather?

    <p>Vasodilation of blood vessels</p> Signup and view all the answers

    What primarily occurs in the synaptic cleft?

    <p>Interaction of neurotransmitters and receptors</p> Signup and view all the answers

    Which receptor type is inhibited by atropine?

    <p>Muscarinic receptors</p> Signup and view all the answers

    What role does the hypothalamus play in the autonomic nervous system?

    <p>It serves as the principal higher center regulating autonomic functions.</p> Signup and view all the answers

    Which part of the brain is responsible for vital functions such as cardiovascular and respiratory control?

    <p>Medulla oblongata</p> Signup and view all the answers

    What effect does stimulation of the anterior nuclei of the hypothalamus have on the autonomic nervous system?

    <p>Enhances parasympathetic functions.</p> Signup and view all the answers

    Which type of reflexes does the midbrain control?

    <p>Micturition and ocular reflexes.</p> Signup and view all the answers

    Which type of autonomic relation is exemplified by salivary secretion?

    <p>Synergistic</p> Signup and view all the answers

    What does the pons regulate in the autonomic system?

    <p>Salivary secretion and respiration.</p> Signup and view all the answers

    What is a consequence of psychological disturbances as noted in the text?

    <p>Gastrointestinal changes.</p> Signup and view all the answers

    Which of the following autonomic functions might be consciously controlled by yoga practitioners?

    <p>Heart rate and respiratory rate.</p> Signup and view all the answers

    What is the primary function of efferent neurons in the nervous system?

    <p>Conducting impulses away from the cell body</p> Signup and view all the answers

    Which cranial nerves are purely sensory?

    <p>C 1, 2 &amp; 8</p> Signup and view all the answers

    What characterizes the sympathetic nervous system's preganglionic fibers?

    <p>Long and myelinated</p> Signup and view all the answers

    What type of ganglia do sympathetic fibers typically pass through?

    <p>Para-vertebral ganglia</p> Signup and view all the answers

    What neurological structure functions primarily as a link between two neurons?

    <p>Interneuron</p> Signup and view all the answers

    Which of the following best describes the role of the adrenal medulla in the sympathetic nervous system?

    <p>Is directly innervated by preganglionic nerve fibers</p> Signup and view all the answers

    Which of the following statements is true regarding the autonomic nervous system?

    <p>Autonomic pathways generally involve a two-neuron chain.</p> Signup and view all the answers

    What functional unit is categorized as 'the unit of reflex action'?

    <p>Reflex arc</p> Signup and view all the answers

    What is the primary function of β3 adrenergic receptors?

    <p>Stimulate lipolysis in adipose tissue</p> Signup and view all the answers

    Which statement accurately describes the role of alpha 1 adrenergic receptors?

    <p>Increase intracellular IP3 and Ca levels</p> Signup and view all the answers

    What is the chief mechanism responsible for maintaining resting membrane potential (RMP)?

    <p>Electrogenic action of the Na-K pump</p> Signup and view all the answers

    Which of the following statements about graded potentials is correct?

    <p>Their duration and magnitude vary with the stimulus</p> Signup and view all the answers

    How does the Na-K pump contribute to nerve excitability?

    <p>By regulating the concentration of Na and K ions</p> Signup and view all the answers

    What characterizes the role of alpha 2 adrenergic receptors in cellular signaling?

    <p>They reduce cAMP levels within cells</p> Signup and view all the answers

    What is the value of the resting membrane potential (RMP) in nerve cells?

    <p>-70mV</p> Signup and view all the answers

    Which ion is primarily responsible for the resting membrane potential (RMP)?

    <p>Potassium ions</p> Signup and view all the answers

    What primarily causes depolarization during an action potential?

    <p>Na+ influx</p> Signup and view all the answers

    What is the duration of the spike potential during an action potential?

    <p>0.5-1 msec</p> Signup and view all the answers

    At which membrane potential does the threshold for an action potential occur?

    <p>-55 mV</p> Signup and view all the answers

    What is the negative after potential due to?

    <p>K+ efflux</p> Signup and view all the answers

    In what phase does the membrane become hyperpolarized following an action potential?

    <p>Negative after potential</p> Signup and view all the answers

    What primarily affects the latent period during nerve impulse transmission?

    <p>Distance between stimulus and nerve fiber</p> Signup and view all the answers

    What is the main cause of the positive after potential?

    <p>Delayed K+ efflux</p> Signup and view all the answers

    Which equation is used to determine the equilibrium potential of an ion?

    <p>Nernst equation</p> Signup and view all the answers

    What type of conduction occurs when impulses travel in the opposite direction in the nervous system?

    <p>Antidromic conduction</p> Signup and view all the answers

    In multiple sclerosis, which of the following characteristics is true?

    <p>It is an autoimmune disease.</p> Signup and view all the answers

    Which fibers are most sensitive to prolonged deep pressure?

    <p>Type A fibers</p> Signup and view all the answers

    What effect does marked hypoxia have on neurons?

    <p>Causes loss of excitability.</p> Signup and view all the answers

    What is the minimum time for synaptic delay in neural transmission?

    <p>0.5 msec</p> Signup and view all the answers

    Which of the following substances is known to increase synaptic transmission?

    <p>Caffeine</p> Signup and view all the answers

    Which condition describes an increase in neuron excitability?

    <p>Alkalosis</p> Signup and view all the answers

    What role do desmosomes play in cellular structure?

    <p>Fasten cells to one another</p> Signup and view all the answers

    Which of the following receptors is primarily activated by steroid hormones?

    <p>Intracellular receptors</p> Signup and view all the answers

    What is the primary function of gap junctions in cellular communication?

    <p>Facilitate the transfer of ions and small molecules between cells</p> Signup and view all the answers

    Which of the following junctions is impermeable to solutes and water?

    <p>Tight junctions</p> Signup and view all the answers

    What distinguishes autocrine signaling from paracrine signaling?

    <p>It acts on the same cell that produces the signal</p> Signup and view all the answers

    Which characteristic is true about G-protein coupled receptors?

    <p>They require a ligand to activate G protein</p> Signup and view all the answers

    What is the composition of gap junctions in terms of protein structure?

    <p>Multimeric connexins forming channels</p> Signup and view all the answers

    What is the primary function of enzyme-linked receptors?

    <p>To convert extracellular signals into intracellular responses through enzyme activation</p> Signup and view all the answers

    Study Notes

    Body Fluid Organization

    • Body fluids constitute 65% (40-42 liters) of an adult weighing 70 kg.
    • Intracellular fluid (ICF): ⅔ of total body fluids (25-28 liters). Found inside cells.
    • Extracellular fluid (ECF): ⅓ of total body fluids (14-15 liters). Found outside cells.
    • ICF is separated from ECF by a semi-permeable cell membrane.
    • ECF provides nutrients and other substances to cells.

    Indicator/Dye Characteristics

    • Non-toxic
    • Non-metabolized
    • Non-excreted
    • Evenly distributed
    • Easily measured

    Measurement of Total Body Water (TBW)

    • Deuterium oxide (D₂O, heavy water) is most frequently used.
    • Tritium oxide and aminopyrine are also used.

    Measurement of ECF Volume

    • Inulin, mannitol, and sucrose are example substances.

    Measurement of Interstitial Fluid Volume

    • Calculated by: Total body water (TBW) - Extracellular fluid (ECF) volume

    Measurement of Plasma Volume

    • Evans blue dye (radioactively labeled albumin) is used.

    Percentage of Total Body Water (TBW)

    • Female: 50%
    • Male: 60%
    • Children: 70%
    • Old age: Decreased.
    • Increased percentage of fat → decreased percentage of water.

    Homeostasis

    • Mechanisms that maintain a constant internal environment.
    • Negative feedback mechanisms: Response inhibits the stimulus (e.g., increased CO₂ → hyperventilation; increased blood glucose → increased insulin)
    • Positive feedback mechanisms: Response increases the stimulus (e.g., heart failure; heart stroke; labor).

    Water Input

    • 2400 ml/day.
    • 2200 ml of exogenous water
    • 200 ml of endogenous water

    Water Output

    • 2400 ml/day
    • Urine: 1500 ml
    • Insensible loss: 700 ml
    • Sweating: 100 ml
    • Feces: 100 ml

    Control of Water Input

    • Thirst center (in the anterior hypothalamus)

    Control of Water Output

    • Antidiuretic hormone (ADH) from the posterior pituitary gland. Its secretion is stimulated by hypertonicity and hypovolemia.

    Cell Membrane Structure

    • Very thin elastic semi-permeable membrane
    • 7.5nm thick
    • 55% proteins
    • 42% lipids
    • 3% carbohydrates.

    Lipids

    • Form the basic membrane structure.
    • Phospholipid heads (hydrophilic, polar)
    • Phospholipid tails (hydrophobic, non-polar)

    Membrane Proteins

    • Intrinsic (integral) proteins: Bind to the hydrophobic center of the lipid bilayer.
    • Transmembrane proteins: Span the entire bilayer (e.g., channels, carriers, pumps, receptors, enzymes).
    • Extrinsic (peripheral) proteins: Bind to hydrophilic polar heads of lipids or peripheral proteins
    • Bind to intracellular surface → cytoskeleton.
    • Bind to extracellular surface → glycocalyx.

    Diffusion

    • Movement of substances down their electrochemical gradient.

    Active Transport

    • Movement of substances against their electrochemical gradient.

    Vesicular Transport

    • Endocytosis: Pushed inside the cell
    • Exocytosis: Pushed outside the cell

    Other Processes and Properties

    • Simple Diffusion: Simple movement without carrier proteins
    • Facilitated diffusion: With carrier proteins.
    • Flux = (Cin - Cout) / ×Osmolarity
    • Tonicity: The ability of particles to cause a change in cell volume.
    • Describe osmolarity relative to plasma.

    Active Transport Mechanisms

    • Primary active transport: Obtains energy directly from ATP hydrolysis (e.g., Na+-K+ ATPase, Ca²⁺-ATPase, K⁺-H⁺-ATPase).
    • Secondary active transport: Uses energy stored in a Na⁺ concentration gradient (e.g., Na⁺-glucose co-transport, Na⁺-Ca²⁺ exchange).

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