Homeostasis in Mammals
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Questions and Answers

What primary function does the nephron serve in the kidney?

  • Regulating the composition of blood (correct)
  • Producing red blood cells
  • Regulating blood sugar levels
  • Filtering lymphatic fluid

    • Which of the following substances are retained in the bloodstream during ultrafiltration?

  • Proteins (correct)
  • Glucose
  • Urea
  • Water

    • What causes the build-up of hydrostatic pressure in the glomerulus?

  • Narrowing of the efferent arteriole (correct)
  • Presence of the glomerular filtrate
  • Widening of the afferent arteriole
  • High blood volume in the renal vein

    • Which of the following processes occurs after ultrafiltration in the nephron?

    <p>Selective reabsorption</p> Signup and view all the answers

    What is the composition of the glomerular filtrate formed during ultrafiltration?

    <p>Water, glucose, mineral ions, and small molecules</p> Signup and view all the answers

    What is the primary cause of Type 1 diabetes?

    <p>Autoimmune destruction of insulin-producing cells</p> Signup and view all the answers

    Which of the following describes Type 2 diabetes?

    <p>It can lead to insulin resistance in cells.</p> Signup and view all the answers

    What condition can arise from the buildup of ketone bodies in the blood due to fat breakdown?

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

    What is one of the serious complications of high blood glucose concentration?

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

    Which factor is NOT associated with the development of Type 2 diabetes?

    <p>Insulin dependency from childhood</p> Signup and view all the answers

    What major health issue can result from untreated diabetes?

    <p>Increased thirst</p> Signup and view all the answers

    What is a possible long-term complication of diabetes?

    <p>Kidney damage leading to failure</p> Signup and view all the answers

    How does dehydration occur in individuals with high blood glucose levels?

    <p>Osmosis pulling water out of cells</p> Signup and view all the answers

    What is the primary function of the nephron?

    <p>To filter and excrete waste products from the blood</p> Signup and view all the answers

    What is the primary effect of ADH binding in the collecting duct?

    <p>Increases permeability to urea</p> Signup and view all the answers

    What type of cells line the proximal convoluted tubule?

    <p>Cuboidal epithelial cells with microvilli</p> Signup and view all the answers

    Which structure within the nephron contains a mass of blood capillaries?

    <p>Renal (Bowman's) capsule</p> Signup and view all the answers

    How do osmoreceptors respond when the water potential of the blood increases?

    <p>They suppress thirst signals</p> Signup and view all the answers

    Why does the efferent arteriole have a smaller diameter than the afferent arteriole?

    <p>To increase blood pressure within the glomerulus</p> Signup and view all the answers

    What is the role of cyclic AMP in cell signaling?

    <p>It amplifies the signal through enzyme activation</p> Signup and view all the answers

    What is the role of the peritubular capillaries?

    <p>To facilitate the reabsorption of essential substances</p> Signup and view all the answers

    What happens to water reabsorption if ADH concentration in the blood decreases?

    <p>Water reabsorption decreases</p> Signup and view all the answers

    Which part of the nephron extends from the cortex into the medulla and then back?

    <p>Loop of Henle</p> Signup and view all the answers

    What initiates the signal cascade in liver cells when stimulated by adrenaline?

    <p>Formation of cyclic AMP</p> Signup and view all the answers

    Which of the following best describes the interaction between the nervous and endocrine systems?

    <p>Both systems maintain constant internal environments</p> Signup and view all the answers

    What distinguishes the distal convoluted tubule from the proximal convoluted tubule?

    <p>It absorbs fewer capillaries</p> Signup and view all the answers

    Which structure becomes increasingly wide as it empties into the pelvis of the kidney?

    <p>Collecting duct</p> Signup and view all the answers

    How does water reabsorption by the collecting duct affect blood water potential?

    <p>Acts to stabilize blood water potential</p> Signup and view all the answers

    What defines a hormone's target cell?

    <p>Cells with complementary receptors</p> Signup and view all the answers

    What is the primary function of antidiuretic hormone (ADH) in the kidneys?

    <p>It increases the permeability of collecting ducts to water.</p> Signup and view all the answers

    How do osmoreceptors in the hypothalamus detect changes in blood water potential?

    <p>By detecting shrinkage from loss of water.</p> Signup and view all the answers

    What initiates the production of ADH in the hypothalamus?

    <p>A decrease in water potential of the blood.</p> Signup and view all the answers

    What is the role of protein kinase activated by ADH in kidney cells?

    <p>To promote the fusion of vesicles with the cell membrane.</p> Signup and view all the answers

    Which scenario can lower the water potential of the blood?

    <p>High salt intake.</p> Signup and view all the answers

    What happens when ADH binds to receptors on kidney cell membranes?

    <p>It activates a secondary messenger system.</p> Signup and view all the answers

    Study Notes

    Homeostasis in Mammals

    • Homeostasis is the maintenance of a constant internal environment, including chemical composition, volume, and other features of blood and tissue fluid. It's crucial for cell function despite external changes.

    • Organisms evolved from simple cells to complex, specialized multicellular ones. This specialization created dependencies among cells, requiring coordination for efficient function.

    • Nervous and endocrine systems coordinate bodily functions through communication. The nervous system communicates rapidly, while the endocrine system is slower and less specific.

    • The internal environment consists of extracellular fluids that bathe cells, providing nutrients and removing wastes, protecting them from external conditions.

    Importance of Homeostasis

    • Enzymes and other cell proteins are sensitive to changes in pH and temperature. Adverse changes reduce enzyme efficiency and can lead to denaturation or affect membrane protein transport.

    • Changes in water potential of blood and tissue fluids can cause cells to shrink or swell beyond repair, hindering normal function.

    Control Mechanisms

    • Control mechanisms involve set points, receptors (detecting stimuli), central control (analyzing information), and effectors (bringing about necessary changes).

    • Negative feedback is a common mechanism in homeostasis, where responses counteract deviations from the set point, restoring balance.

    • Positive feedback (less common) amplifies deviations from the set point, resulting in a more significant change. Examples include childbirth contractions and nerve impulses.

    Coordination of Mechanisms

    • Organisms use multiple receptors and effectors, analyzing information from many sources for effective control. Coordination is vital.

    • The brain and other control centers receive information from various receptors and coordinate effector responses to counter change. This integrates information from different sources before response.

    Excretion and Kidney Structure

    • Excretion is the removal of metabolic wastes from the body.

    • Urea is produced in the liver from excess amino acids via deamination and the urea cycle.

    • Kidneys are bean-shaped organs responsible for filtering blood and producing urine to eliminate waste products.

    • Key kidney structures include the fibrous capsule, cortex, medulla, renal pelvis, ureter, renal artery, and renal vein.

    Nephron Structure

    • The nephron is the functional unit of the kidney, a narrow tube consisting of the renal capsule, proximal convoluted tubule, loop of Henlé, distal convoluted tubule, and collecting duct.

    • Blood vessels like afferent and efferent arterioles, glomerulus, and peritubular capillaries are associated with each nephron.

    • Specialized cells such as podocytes are part of the structure for rapid filtration.

    Kidney Function (Ultrafiltration & Selective Reabsorption)

    • Ultrafiltration is the pressure-driven filtration of blood plasma in the glomerulus, producing a filtrate similar to blood plasma but lacking large proteins.

    • Selectively reabsorbing valuable substances (glucose, salts, water) back into the bloodstream from filtrate is a crucial kidney function, ensuring homeostasis.

    Control of Water and Solute Concentration (Regulation)

    • The hypothalamus (brain region) monitors water potential of blood. Osmoreceptors detect changes and stimulate the posterior pituitary to release ADH (antidiuretic hormone).

    • ADH increases the permeability of collecting duct cells, allowing more water reabsorption and producing concentrated urine. Maintaining a constant blood water potential is critical for homeostasis.

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    Homeostasis in Mammals PDF

    Description

    Explore the concept of homeostasis in mammals, focusing on how internal environments are maintained despite external changes. Learn about the roles of the nervous and endocrine systems in coordinating bodily functions and the impact of pH and temperature on cell proteins.

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