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Mekdes Beyene
Physiology Unit 7 - 13
| Question | Answer |
|---|---|
| What is the main function of a neuron? | A neuron's main function is to process information and communicate by sending and receiving electrochemical signals. |
| How do neurons communicate with each other? | When a signal reaches the end of a neuron, it releases neurotransmitters into the synapse. These chemicals diffuse across the gap and bind to receptors on the next neuron, triggering a new signal in that cell. |
| What are the three main parts of a neuron? | The three main parts are the cell body, dendrites, and axon. Dendrites receive signals, the cell body processes them, and the axon transmits them away from the cell body. |
| What is the role of glial cells? | Glial cells support and protect neurons by providing nutrients, maintaining the chemical balance, forming the myelin sheath for insulation, and producing cerebrospinal fluid |
| What causes a nerve impulse (action potential)? | An action potential is triggered when a neuron receives a stimulus that reaches a certain threshold. This causes a rapid influx of sodium ions (Na+), which reverses the charge across the cell membrane and sends an electrical impulse down the axon. |
| Where is cerebrospinal fluid (CSF) produced, how does it circulate, and what is its main function? | CSF is produced by the choroid plexus in the ventricles. It circulates through the ventricles → central canal → subarachnoid space → reabsorbed by arachnoid villi into venous sinuses. Its functions include cushioning the CNS, maintaining chemical balance, |
| What are the two primary functions of the spinal cord? | The spinal cord provides neural pathways for sensory and motor signals and acts as a reflex center for rapid, involuntary responses. |
| What are the three major divisions of the brainstem and their functions? | Midbrain (visual/auditory reflexes), Pons (respiratory regulation, relays signals), Medulla Oblongata (vital functions: HR, BP, breathing). |
| Which embryonic structures form the major brain regions? | The forebrain, midbrain, and hindbrain (prosencephalon, mesencephalon, rhombencephalon) develop into the cerebrum, brainstem, and cerebellum. |
| What are the four major nerve plexuses and an example nerve from each? | Cervical (phrenic nerve), Brachial (median nerve), Lumbar (femoral nerve), Sacral (sciatic nerve). |
| Why are dermatomes and myotomes clinically significant? | They map sensory and motor regions supplied by spinal nerves and help locate nerve or spinal cord injuries. |
| What are the three functional roles of the cerebral cortex? | Sensory (perception), motor (voluntary movement), integrative (memory, language, decision-making). |
| How do somatic sensory pathways differ from somatic motor pathways? | Sensory pathways carry afferent signals to the CNS; motor pathways carry efferent signals to skeletal muscles. |
| How many cranial nerves are there, and what are their general functions? | There are 12 cranial nerves, responsible for special senses, facial movement, autonomic control, and swallowing. |
| What is the main difference between the sympathetic and parasympathetic nervous systems? | Sympathetic: “Fight or flight”—increases HR, dilates bronchi, mobilizes energy. Parasympathetic: “Rest and digest”—slows HR, stimulates digestion, conserves energy. |
| How do general sense organs differ from special sense organs? | General senses detect touch, pressure, pain, temperature, and body position through receptors found throughout the body. Special senses (vision, hearing, taste, smell, equilibrium) use highly specialized organs located in the head. |
| What is adaptation in sensory receptors? | Adaptation is when receptors become less responsive to continuous stimulation, reducing the perception of a constant stimulus (e.g., clothes on skin). |
| How does the ear convert sound waves into nerve impulses? | Sound waves vibrate the tympanic membrane → ossicles → cochlear fluid, bending hair cells in the organ of Corti. This creates electrical impulses sent to the brain via CN VIII. |
| What are the four processes that focus light on the retina? | Refraction, accommodation, constriction of the pupil, and convergence of the eyes |
| How does endocrine regulation differ from nervous system regulation? | The nervous system provides fast, short-term responses via electrical impulses. The endocrine system uses hormones for slower, long-lasting control. |
| What is the key difference between steroid and nonsteroid hormone action? | Steroid hormones enter the cell and act directly on DNA. Nonsteroid hormones bind to receptors on the cell membrane and use second messengers. |
| What are up-regulation and down-regulation? | Up-regulation: increased number of receptors → higher sensitivity. Down-regulation: decreased receptors → lower sensitivity to hormones. |
| What is the main difference between endocrine hypersecretion and hyposecretion? | Hypersecretion: too much hormone (e.g., hyperthyroidism). Hyposecretion: too little hormone (e.g., diabetes mellitus). |
| Which hormones are produced by the pancreas and what do they do? | Insulin lowers blood glucose, glucagon raises blood glucose, and somatostatin inhibits both insulin and glucagon release. |
| What are the hormonal functions of the ovaries and testes? | Ovaries: produce estrogen and progesterone for reproduction and menstrual cycle regulation. Testes: produce testosterone for sperm production and male secondary characteristics. |
| What are the main functions and components of blood? | Blood transports gases, nutrients, hormones, and wastes; regulates temperature and pH; and protects through clotting and immunity. It contains plasma (fluid) and formed elements (RBCs, WBCs, platelets). |
| Where are formed elements made and what is the process called? | Formed elements develop in red bone marrow through hematopoiesis, beginning with a hematopoietic stem cell. |
| What is the primary function of red blood cells? | RBCs transport oxygen and carbon dioxide using hemoglobin, which binds O₂ in the lungs and releases it to tissues. |
| How do platelets contribute to hemostasis? | Platelets form a platelet plug, release chemicals that trigger clotting, and activate fibrin formation to stabilize the clot. |
| How does heart structure support its function as a pump? | The heart has four chambers, one-way valves, and a thick muscular left ventricle, allowing coordinated pumping of blood throughout the body. |
| What are the major phases of the cardiac cycle? | Systole (ventricular contraction and ejection) and diastole (ventricular relaxation and filling). |
| How do pulmonary and systemic circulation differ? | Pulmonary circulation moves blood from the heart to the lungs for gas exchange. Systemic circulation delivers oxygenated blood from the heart to the body. |
| Trace deoxygenated and oxygenated blood through the heart. | Deoxygenated: SVC/IVC → Right Atrium → Right Ventricle → Pulmonary Arteries → Lungs Oxygenated: Pulmonary Veins → Left Atrium → Left Ventricle → Aorta → Body |
| Which brain centers control heart rate? | The cardiac centers in the medulla oblongata—the cardioacceleratory center (increases HR via sympathetic input) and cardioinhibitory center (decreases HR via vagus nerve). |
| Why is hemoglobin essential for oxygen transport? | Hemoglobin binds oxygen efficiently and carries four molecules of O₂ per molecule, enabling high-capacity gas transport vital for tissue oxygenation. |
| What are the primary functions of lymph fluid, vessels, ducts, and organs? | The lymphatic system drains excess interstitial fluid, transports lipids, returns proteins to the blood, and houses immune cells that filter and destroy pathogens. |
| How do primary and secondary lymphatic organs differ? | Primary organs (bone marrow, thymus) produce and mature lymphocytes. Secondary organs (lymph nodes, spleen, tonsils, MALT) provide sites for immune activation and filtration. |
| What mechanisms move lymph through the lymphatic system? | Lymph moves via the lymphatic pump, skeletal muscle contractions, breathing movements, one-way valves, and pressure changes during tissue activity. |
| What is the role of the innate immune system? | The innate system provides immediate, nonspecific defense through barriers, inflammation, phagocytes, NK cells, and fever. |
| How do the immune and lymphatic systems interact with other systems? | They work with the circulatory system for transport, the integumentary system for barriers, and the endocrine system to regulate immune activity. |
| What are the two major categories of immune mechanisms? | Innate immunity (nonspecific, immediate) and adaptive immunity (specific, memory-based). |
| What triggers the inflammatory response and what is its function? | Tissue injury triggers inflammation; it increases blood flow, brings immune cells, removes debris, and prepares tissue for repair. |
| What is phagocytosis in immune defense? | Phagocytes (neutrophils, macrophages) engulf and digest pathogens and debris. |
| What roles do NK cells and interferons play in immunity? | NK cells kill virus-infected and cancerous cells. Interferons block viral replication and activate immune cells. |
| What are the main functions of antibodies? | Antibodies neutralize toxins, agglutinate pathogens, activate complement, and tag invaders for destruction by immune cells. |
| What integrated processes ensure adequate oxygen delivery and CO₂ removal? | Pulmonary ventilation, external respiration, gas transport, internal respiration, and cellular respiration work together to oxygenate tissues and remove carbon dioxide. |
| What is pulmonary ventilation and how does quiet breathing occur? | Pulmonary ventilation is the movement of air into and out of the lungs. Quiet inspiration is active (diaphragm contracts), while quiet expiration is passive (diaphragm relaxes). |
| Define tidal volume, IRV, ERV, residual volume, and minimal volume. | TV: Air of a normal breath IRV: Extra air inhaled after TV ERV: Extra air exhaled after TV RV: Air left after max exhalation Minimal Volume: Air left after lung collapse |
| What are inspiratory capacity, FRC, and TLC? | IC = TV + IRV FRC = ERV + RV TLC: Total of all lung volumes |
| How does spirometry assess airflow? | Spirometry measures lung volumes and flow rates to diagnose obstructive and restrictive disorders. |
| Define total minute volume, FEV₁, VO₂ max, and flow-volume loop. | Minute volume: TV × RR FEV₁: Air exhaled in 1 second VO₂ max: Max O₂ use during exercise Flow-volume loop: Graph of inhalation/exhalation flow |
| Why must ventilation and perfusion match? | Efficient gas exchange requires equal air flow and blood flow; mismatches lead to hypoxia or retention of CO₂. |
| What mainly controls respirations? | The medulla and pons respond primarily to ↑CO₂ and ↑H⁺ (low pH), adjusting ventilation to maintain homeostasis. |
| How do partial pressures drive gas exchange? | Gases move from high → low partial pressure: O₂ diffuses from alveoli to blood; CO₂ diffuses from blood to alveoli. |
| What are the Bohr and Haldane effects? | Bohr: High CO₂/H⁺ decreases hemoglobin’s O₂ affinity → more O₂ delivered to tissues. Haldane: Deoxygenated blood binds CO₂ more easily → enhances CO₂ uptake in tissues and release in lungs. |
| Which four primary mechanisms describe the overall function of the digestive system? | Ingestion, digestion (mechanical & chemical), absorption, and elimination. |
| What is the definition of mechanical digestion, and where does it begin? | Mechanical digestion is the physical breakdown of food into smaller pieces; it begins with mastication in the mouth. |
| What is the main function of mastication? | To break down food mechanically, mix it with saliva, and form a bolus that is easier to swallow and digest. |
| List the three stages of deglutition (swallowing) in order. | Oral (voluntary), pharyngeal (involuntary), and esophageal (involuntary) stages. |
| What is the key difference between peristalsis and segmentation? | Peristalsis propels food forward through wave-like contractions; segmentation mixes food with digestive juices without forward movement. |
| During stomach emptying, which factor determines how quickly chyme moves into the duodenum? | Hormonal control (gastrin speeds up; CCK & secretin slow down) and the composition of chyme (fats slow gastric emptying). |
| Define chemical digestion and identify what it relies on. | Chemical digestion is the breakdown of food into smaller chemical units using enzymes and digestive secretions. |
| What is an enzyme, and how are digestive enzymes classified? | Enzymes are biological catalysts; they are classified as amylases (carbs), proteases (proteins), lipases (fats), and nucleases (nucleic acids). |
| Which nutrients are absorbed into blood capillaries, and which enter lacteals? | Carbohydrates, amino acids, and water-soluble vitamins enter blood capillaries; fats and fat-soluble vitamins enter lacteals. |
| What triggers the defecation reflex, and which sphincter is voluntary? | Stretch receptors in the rectum trigger the reflex; the external anal sphincter is voluntary. |
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Twin0324