# Biologia Marina — Intermedi (B1/B2) 1: Human Physiology & Organ Systems > [Català] Biologia Marina: Major organ systems including circulatory, respiratory, digestive, excretory, and endocrine systems and homeostasis - **Canonical URL:** https://flashcards.world/flashcards/sets/b6f6e5ee-964f-4eea-ae29-c8c356777d4a/ - **Markdown URL:** https://flashcards.world/flashcards/sets/b6f6e5ee-964f-4eea-ae29-c8c356777d4a.md - **Level:** intermediate - **Languages:** ca → ca - **Total Cards:** 32 ## Flashcards (32 Cards) | # | Front (Term / Prompt) | Back (Definition / Answer) | Example | Multiple-Choice Options | | :--- | :--- | :--- | :--- | :--- | | 1 | What are the three distinct anatomical layers of human skin from superficial to deep? | Epidermis (keratinized stratified squamous epithelium), dermis (connective tissue with vessels/nerves), and hypodermis/subcutaneous tissue (adipose and loose connective tissue). | | | | 2 | Why do steroid hormones utilize intracellular receptors while peptide hormones bind extracellular surface receptors? | Steroid hormones are lipophilic and diffuse freely across the lipid bilayer; peptide hormones are hydrophilic and cannot penetrate the hydrophobic membrane. | | | | 3 | How do insulin and glucagon coordinate blood glucose homeostasis from the pancreatic islets of Langerhans? | Beta cells secrete insulin to stimulate cellular glucose uptake, glycolysis, and glycogenesis; alpha cells secrete glucagon during fasting to promote glycogenolysis and gluconeogenesis. | | | | 4 | What specialized tissue acts as the primary physiological pacemaker of the human heart? | The sinoatrial (SA) node located in the superior wall of the right atrium. | | | | 5 | Why is there an intrinsic delay of approximately 0.1 seconds at the atrioventricular (AV) node? | To ensure the atria fully contract and empty their blood into the ventricles before ventricular systole begins. | | | | 6 | What physiological factors cause a rightward shift of the oxygen-hemoglobin dissociation curve (the Bohr effect)? | Increased CO2 partial pressure, decreased pH (higher acidity), increased temperature, and elevated 2,3-bisphosphoglycerate (2,3-BPG), all promoting oxygen unloading to tissues. | | | | 7 | Which two peptide hormones are synthesized in the hypothalamus and stored/released by the posterior pituitary (neurohypophysis)? | Oxytocin and antidiuretic hormone (ADH / vasopressin). | | | | 8 | Which organelle in skeletal muscle stores and releases intracellular calcium ions for excitation-contraction coupling? | The sarcoplasmic reticulum (via terminal cisternae and ryanodine receptors). | | | | 9 | What distinguishes endocrine signaling from paracrine and autocrine chemical signaling? | Endocrine hormones travel through the bloodstream to distant target tissues; paracrine signals act on neighboring cells; autocrine signals act on the secreting cell itself. | | | | 10 | What primary stimuli trigger renin secretion by juxtaglomerular cells in the renal apparatus? | Decreased renal perfusion pressure, sympathetic nerve stimulation (beta-1 receptors), and decreased sodium delivery to the macula densa. | | | | 11 | What are the two anatomical divisions of the autonomic nervous system, and what are their overarching roles? | Sympathetic system mediates 'fight-or-flight' emergency catabolic responses; parasympathetic system mediates 'rest-and-digest' vegetative anabolic functions. | | | | 12 | Give a physiological example of a positive feedback loop in human biology. | Oxytocin release during childbirth, where uterine contractions stimulate cervical stretch, triggering greater oxytocin secretion until delivery. | | | | 13 | What is the primary action of Antidiuretic Hormone (ADH / vasopressin) on renal water reabsorption? | It stimulates insertion of aquaporin-2 water channels into the apical membranes of collecting duct principal cells, increasing water reabsorption and concentrating urine. | | | | 14 | How is the majority of carbon dioxide transported from peripheral tissues to the lungs in human venous blood? | As dissolved bicarbonate ions (HCO3-) in blood plasma (~70%), converted from CO2 and water by erythrocyte carbonic anhydrase. | | | | 15 | What causes rigor mortis following death? | Cellular ATP depletion prevents ATP from binding to myosin heads, locking actin-myosin cross-bridges in a persistent contracted state. | | | | 16 | How does pepsinogen become activated into active pepsin within the gastric lumen? | Exposure to acidic gastric juice (pH ~1.5–2.0) causes autocatalytic cleavage of pepsinogen into active pepsin. | | | | 17 | How do the structural walls of arteries and veins differ in relation to their hemodynamic functions? | Arteries have thicker tunica media with elastic and smooth muscle layers to withstand high systolic pressures; veins have thinner walls, wider lumens, and one-way valves. | | | | 18 | How does the countercurrent multiplier mechanism in the loop of Henle establish an osmotic gradient in the renal medulla? | The descending limb is permeable to water but not solutes; the ascending limb actively pumps Na+ and Cl- out but is impermeable to water, creating hypertonic medullary interstitium. | | | | 19 | According to the sliding filament model of skeletal muscle contraction, what role does Ca2+ play in initiating cross-bridge cycling? | Ca2+ binds troponin C, causing a conformational shift in tropomyosin that exposes myosin-binding sites on actin filaments. | | | | 20 | Which cell types in the gastric mucosa secrete hydrochloric acid (HCl) and pepsinogen respectively? | Parietal cells secrete HCl (and intrinsic factor); chief cells secrete the inactive zymogen pepsinogen. | | | | 21 | What are the primary digestive roles of bile salts synthesized in the liver and concentrated in the gallbladder? | They emulsify dietary lipids into microscopic droplets, drastically increasing surface area for pancreatic lipase hydrolysis. | | | | 22 | What physical mechanism drives inhalation during resting human pulmonary ventilation? | The diaphragm contracts downward and external intercostals elevate ribs, expanding thoracic volume, lowering intrapleural pressure, and drawing air in by negative pressure. | | | | 23 | How does aldosterone regulate renal electrolyte balance and systemic blood pressure? | It upregulates basolateral Na+/K+ pumps and apical epithelial Na+ channels (ENaC) in distal tubules and collecting ducts, reabsorbing Na+ (and water) while secreting K+ and H+. | | | | 24 | What three sequential physiological processes produce urine within the nephron? | 1. Glomerular filtration 2. Tubular reabsorption 3. Tubular secretion. | | | | 25 | Trace the pathway of deoxygenated blood through the heart to the lungs and back as oxygenated blood. | Vena cavae -> right atrium -> tricuspid valve -> right ventricle -> pulmonary valve -> pulmonary arteries -> lungs -> pulmonary veins -> left atrium -> bicuspid (mitral) valve -> left ventricle -> aortic valve -> aorta. | | | | 26 | Which anatomical adaptations maximize nutrient absorption across the small intestine mucosa? | Circular folds (plicae circulares), finger-like villi, and microvillar brush border membranes, providing a massive absorptive surface area. | | | | 27 | What is the critical physiological function of pulmonary surfactant produced by Type II alveolar pneumocytes? | It reduces alveolar surface tension, preventing alveolar collapse (atelectasis) at low lung volumes during exhalation. | | | | 28 | What event causes the detachment of the myosin head from the actin filament during muscle relaxation or cycling? | Binding of a new ATP molecule to the nucleotide-binding site on the myosin head. | | | | 29 | Which two hormones inversely regulate systemic blood calcium levels, and what are their sources? | Parathyroid hormone (PTH) from parathyroid glands increases serum Ca2+; calcitonin from thyroid parafollicular (C) cells decreases serum Ca2+. | | | | 30 | What is homeostasis, and how does a negative feedback loop maintain physiological parameters within set points? | Homeostasis is dynamic physiological equilibrium; negative feedback detects deviations from a set point and triggers corrective effector responses to reverse the change. | | | | 31 | What is the functional structural unit of the human kidney? | The nephron, consisting of a renal corpuscle (glomerulus and Bowman's capsule) and a tubular system. | | | | 32 | Which cell type and quaternary protein are responsible for oxygen transport in human arterial blood? | Erythrocytes (red blood cells) containing hemoglobin, a tetrameric protein with four iron-bearing heme groups. | | | --- Study this deck interactively with FSRS-6 spaced repetition, audio review, and multiple-choice mode at [Flashcards World](https://flashcards.world/flashcards/sets/b6f6e5ee-964f-4eea-ae29-c8c356777d4a/).