PAR3623 Paramedicine Medical Physiology I F2024 Lecture 15 PDF

PAR3623 Paramedicine – Medical Physiology I F2024 Lecture 15 Urinary System Overview  Copyright / Intellectual Property Notice Materials posted to courses are subject to Intellectual Property and Copyright protection, and as such cannot be used and posted for...

PAR3623 Paramedicine – Medical Physiology I F2024 Lecture 15 Urinary System Overview  Copyright / Intellectual Property Notice Materials posted to courses are subject to Intellectual Property and Copyright protection, and as such cannot be used and posted for public dissemination without prior permission from the College. For clarity, these protections are automatic once a work is created, and applies whether or not a copyright statement appears on the material. Students are bound by College policies, including AA 34 - Copyright, and SA 07 - Student Code of Conduct, and any student found to be using or posting course materials for public dissemination without permission is in breach of these policies and may be sanctioned.  Skeletal muscle § Layers of sk.m § Troponin isoforms § Multi vs single unit smooth muscles § Muscle twitches – which is a contraction? § Training and muscle fiber types Smooth muscle § G proteins – smooth muscle and other visceral tissues § cAMP second messenger Dr. Pasan Fernando  Need HELP?? If you need help: 1. Email me for an appointment – can meet individually or as a group 2. Chat with me after or before class Email responses follow the AC policy – 48h grace (not including weekends and holidays) Expect email responses from me during regular College business hours with some exceptions. Ø After the 48h, please send me a polite reminder. J Dr. Pasan Fernando 4  Layers of skeletal muscle § Muscle tissue has 3 layers or coverings (like most other organs in the body) § The coverings are predominantly connective tissue § Epimysium – dense, surrounds the entire muscle organ, blends with fascia/tendon - attachment § Perimysium – fibrous, surrounds groups of muscle fibers to make a collection of fascicles – bundles together § Endomysium – fine, surrounds Dr. Pasan Fernando each muscle fiber – layer of protection before sarcolemma 5  Troponin isoforms Dr. Pasan Fernando 6  Types of smooth muscle Single unit Multi unit § Most common type § Not as common § No gap junctions; contraction is § Electrically coupled via gap confined to the stimulated cells junctions § Unit contraction - contraction of § Asynchronous contraction one leads to contraction of the group § Large blood vessels, respiratory airways § Walls of visceral organs (excluding Dr. Pasan Fernando heart) § Slow steady contractions 7  Types of muscle twitches § Represents the force (tension) generated by a single muscle fiber (single cell) § An entire muscle will have the same pattern but higher tension § All twitch types are generating tension § In all cases, the sarcomere has shortened § So, in all cases, there is a Dr. Pasan Fernando contraction (force) 8  Muscle fiber types Characteristic Slow Oxidative (SO) Fast Oxidative–Glycolytic Fibers Fast Glycolytic (FG) Fibers (FOG) Fibers Fiber diameter Smallest. Intermediate. Largest. Myoglobin content Large amount. Large amount. Small amount. Mitochondria Many. Many. Few. Capillaries Many. Many. Few. Color Red. Red-pink. White (pale). Capacity for generating ATP High capacity, by aerobic Intermediate capacity, by Low capacity, by anaerobic and method used respiration. both aerobic respiration glycolysis. and anaerobic glycolysis. Dr. Pasan Fernando Rate of ATP hydrolysis by Slow. Fast. Fast. myosin ATPase  Muscle fiber types Characteristic Slow Oxidative (SO) Fibers Fast Oxidative–Glycolytic Fibers Fast Glycolytic (FG) (FOG) Fibers Contraction velocity Slow. Fast. Fast. Fatigue resistance High. Intermediate. Low. Creatine kinase Lowest amount. Intermediate amount. Highest amount. Glycogen stores Low. Intermediate. High. Order of recruitment First. Second. Third. Location where fibers are Postural muscles such as Lower limb muscles. Upper limb muscles. abundant those of the neck. Primary functions of fibers Maintaining posture and Walking, sprinting. Rapid, intense movements of Dr. Pasan Fernando aerobic endurance activities. short duration.  Dr. Pasan Fernando 11  Dr. Pasan Fernando Urinary System 12  Overview of the Urinary System Two kidneys § Major excretory organs of urinary system § Urine: water, ions, small molecule substances § Receive 25% of cardiac output at rest § Excretory functions of the urinary system – produce and excrete urine Dr. Pasan Fernando 13  Urinary System – Major organs § Ureters—receive urine from the kidneys Ø Conduct urine to the urinary bladder by gravity and peristalsis § Urinary bladder—receives and stores urine Ø Contraction of muscle in walls drives urination § Urethra—conducts urine from the bladder to outside the body Dr. Pasan Fernando 14  Functions of Urinary System - Overview Blood/plasma volume and blood pressure Regulate plasma osmolarity and ionic balance Regulates plasma pH Dr. Pasan Fernando Eliminates drugs and toxins Prevents loss of nutrients 15  Gross Anatomy of the Kidneys § Retroperitoneal, in the superior lumbar region Ø Located between T12 and L5 § Right kidney is crowded by liver, so is lower than left § Adrenal (suprarenal) gland sits atop each kidney § Convex lateral surface § Concave medial surface with vertical renal hilum leads to internal space, renal sinus Ø Ureters, renal blood vessels, lymphatics, and nerves enter and exit at hilum Dr. Pasan Fernando 16  Kidney Location and Structure Kidney structure § Reddish brown § Approx. 4 inches long x 2 inches wide; 150 g § Hilum § Medial indentation § Point of entry for renal vasculature, ureter, renal nerves § Located in a retroperitoneal position Ø Between the muscles of the posterior body wall and the parietal peritoneum § Connected to the urinary bladder by the ureters Ø Empty into the posterior, inferior Dr. Pasan Fernando surface of the urinary bladder 17  Kidney Structure and Location Three layers of supportive tissue surround kidney § Fibrous capsule § Perirenal fat capsule § Renal fascia Dr. Pasan Fernando 18  Kidney Location and Structure Position of the kidneys are maintained by: § Overlying peritoneum § Adjacent visceral organs § Supporting connective tissues Connective tissues supporting kidney § Fibrous capsule (layer of collagen fibers) Ø Covers the outer surface of the kidney Ø Projects collagen fibers through the perinephric fat to the renal fascia Dr. Pasan Fernando 19  Kidney Location and Structure Connective tissues supporting kidney (continued) § Renal fascia (dense, fibrous outer layer) Ø Anchors the kidney to surrounding structures § Perirenal fat Ø Thick layer of adipose tissue Dr. Pasan Fernando 20  The Pensive Paramedic……. Martine is 32-years old. Her primary complaint is intermittent right abdominal pain. When standing upright, the pain is exacerbated. When supine, the pain diminishes. She indicated that whenever she moves from supine to prone, she has a feeling of a tennis ball rolling inside her. The pain is further exacerbated with moderate consumption of alcohol followed by frequent micturition. Three years prior, she had a successful pregnancy in which the pain was evident in the first and second trimester only. Dr. Pasan Fernando Physical and abdominal exams found her to be of a thin physique but otherwise unremarkable. 21  Dissecting the complaint Define the term micturition. Provide a summary of Martine’s complaints. What actions exacerbate Martine’s symptoms? What observations help to identify the kidney as a likely target organ of Martine’s symptoms? Dr. Pasan Fernando Based on your current understanding of the kidney, provide a possible explanation for Martine’s symptoms. 22  Nephroptosis § Described as a floating kidney § Kidney descends more than two vertebral bodies (> 5 cm) during postural movement § Most common in thin women; often asymptomatic § Abdominal pain that improves with lying supine; often alleviated with pregnancy § Imaging diagnosis is most definitive test § Standard of care is laparoscopic nephropexy Dr. Pasan Fernando 23  Review A. What structures enter and exit the kidney at the hilum? B. Describe the concentric layers of connective tissue that protect and anchor the kidney. C. What would happen to a kidney’s position if the perinephric fat layer were depleted and the collagen fibers of the fibrous capsule were to become detached? You should be able to: Describe the location and structural features of the kidney Dr. Pasan Fernando 24  Kidney – Major structural features Major structural landmarks § Fibrous capsule Ø Lines the renal sinus (internal cavity within the kidney) § Renal cortex (superficial region of the kidney) Dr. Pasan Fernando 25  Kidney – Major structural features § Renal medulla (inner region of the kidney) Ø Renal pyramid (conical structure in the medulla) – Renal papilla (tip of the pyramid) Ø Renal column (separates adjacent pyramids Dr. Pasan Fernando 26  Kidney – Major structural features § Kidney lobe (pyramid, the overlying cortex, and adjacent renal columns) Ø Each kidney contains approx. 6 lobes Dr. Pasan Fernando 27  Kidney – Major structural features Other major features of the kidney § Hilum Ø Medial indentation in the kidney § Minor calyx Ø Collects urine from a single kidney lobe § Major calyx Ø Forms from the fusion of 4–5 minor calyces § Renal pelvis Ø Funnel-shaped structure that collects urine from major calyces Ø Continuous with the ureter Dr. Pasan Fernando 28  Dr. Pasan Fernando 29  Renal Blood Supply Blood: kidneys cleanse blood and adjust its composition Therefore it is critical for the kidneys to receive a rich supply of blood § Renal arteries deliver about one-fourth (1200 ml) of cardiac output to kidneys each minute § Arterial flow: renal à segmental à interlobar à arcuate à cortical radiate (interlobular) § Venous flow: cortical radiate à arcuate à interlobar à renal veins Ø No segmental veins Dr. Pasan Fernando 30  Renal Blood Supply Dr. Pasan Fernando 31  Renal Nerve Supply Renal plexus § Network of autonomic nerve fibers and ganglia § Supplies kidneys and ureters § Comes off of the celiac plexus § Regulate renal blood flow § Stimulate release of renin Dr. Pasan Fernando 32  Review A. Which structure is a conical mass within the renal medulla that ends at the papilla? B. Compare the minor and major calyces. C. Which type of nephron is essential for water conservation and concentrated urine production? You should be able to: Ø Describe the gross structural features of the kidney, detailing the flow of urinary fluid through the microscopic and macroscopic Dr. Pasan Fernando segments Ø Distinguish between cortical and juxtamedullary nephrons. 33  Kidney – Microscopic features Two types of nephrons § Microscopic functional units of the kidney § Approx. 1 million/kidney 1. Cortical nephrons – 85 percent of all nephrons – Located primarily in the cortex – Responsible for most regulatory functions 2. Juxtamedullary nephrons Ø 15 percent of all nephrons Ø Long nephron loop extending deep into medulla Dr. Pasan Fernando Ø Essential to producing concentrated urine 34  The Nephron – Overview Two components 1. Renal corpuscle Ø Blood pressure forces water and solutes out of the glomerular capillaries in a process called filtration – Produces filtrate (protein-free solution, similar to blood plasma) Ø Collected in the surrounding capsular space 2. Renal tubule Ø Tubular passageway up to 50 mm long Ø Receives filtrate and modifies it to create urine Dr. Pasan Fernando 35  Renal Corpuscle - Glomerulus Two parts of renal corpuscle 1. Glomerulus § Tuft of capillaries composed of fenestrated endothelium Ø Highly porous capillaries Ø Allows for efficient filtrate formation – Filtrate: plasma-derived fluid that renal tubules process to form urine Dr. Pasan Fernando 36  Renal Corpuscle – Glomerular capsule 2. Glomerular capsule § Also called Bowman’s capsule: cup- shaped, hollow structure surrounding glomerulus § Consists of two layers Ø Parietal layer: simple squamous epithelium Ø Visceral layer : clings to glomerular capillaries; branching epithelial podocytes – Extensions terminate in foot processes that cling to basement membrane Dr. Pasan Fernando – Filtration slits between foot processes allow filtrate to pass into capsular space 37  Formation of the Filtration Membrane Dr. Pasan Fernando 38  Nephron – Proximal convoluted tubule Proximal convoluted tubule (PCT) Ø Reabsorbs nutrients from the filtrate (now called tubular fluid) Ø Winding nature increases residence time in tubules Ø Allows optimum time for exchange of tubular fluid components Ø Cuboidal epithelium Dr. Pasan Fernando 39  Nephron – Nephron loop 2. Nephron loop § Formerly called loop of Henle § U-shaped structure consisting of two limbs Ø Descending limb – Proximal part of descending limb is continuous with proximal tubule – Distal portion also called descending thin limb; simple squamous epithelium Ø Ascending limb – Thick ascending limb » Thin in some nephrons Dr. Pasan Fernando – Cuboidal or columnar cells 40  Nephron – Distal convoluted tubule Distal convoluted tubule (DCT) § Cuboidal cells with very few microvilli § Function more in secretion than reabsorption § Confined to cortex Dr. Pasan Fernando 41  Nephron - Segments § Direction of flow for tubular fluid and surrounding interstitial fluid (peritubular fluid) varies at each nephron segment § Water and solutes are reabsorbed in different regions of nephron § Reabsorption can be regulated by hormones in some regions (variable) Dr. Pasan Fernando 42  Nephron – Collecting system Collecting system § Series of tubes carrying tubular fluid away from the nephron § Collecting duct Ø Collects fluid from many nephrons Ø Carries fluid through the renal medulla Ø Lined with two main types of cells: – Intercalated cells (play a role in secreting and reabsorbing hydrogen and bicarbonate ions) – Principal cells (reabsorb water and Na+, secrete K+) Dr. Pasan Fernando 43  Nephron – Collecting system § Papillary duct Ø Collects fluid from multiple collecting ducts Ø Delivers fluid to minor calyx Dr. Pasan Fernando 44  v How do the structures of the kidney (tissues, cells, etc.), facilitate the function of 'elimination' from the kidney? v Describe the features of epithelial cells that line the various nephron segments. How are they designed to facilitate kidney function? v What physiological parameters are needed for effective renal function? Dr. Pasan Fernando PAR3623 45