Urinary and Reproductive Systems Physiology PDF

10/2/2023 Urinary System: Fox Chapter 17 © STANBRIDGE UNIVERSITY 2023 1 1  10/2/2023 Objectives List the main components of the urinary system Understand the function of...

10/2/2023 Urinary System: Fox Chapter 17 © STANBRIDGE UNIVERSITY 2023 1 1  10/2/2023 Objectives List the main components of the urinary system Understand the function of the various aspects of the urinary system Describe the pathway of filtrate in the nephron © STANBRIDGE UNIVERSITY 2023 2 2  10/2/2023 Urinary System – The Lay of the Land Kidneys —form urine Ureters —transport urine from kidneys to bladder Bladder —stores urine; located in hypogastric region Urethra —excrete urine from bladder to outside of body Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 3 3  10/2/2023 Location of Kidneys in Reference to the Thorax The kidneys are generally located at the level between T12-L3 with some protection from the ribs Right kidney sits slightly lower than the left because the liver is above it Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 4 4  10/2/2023 Functions of the Urinary (Renal) System Excretion – eliminating metabolic waste (urea-made in liver from amino acids) and drugs/toxins Maintains balance of water, sodium, potassium, and calcium Acid–Base balance of body fluids Blood pressure regulation The kidneys produce renin (a hormone) which activates Angiotensin II which constricts blood vessels to ↑BP Red blood cell production regulation The kidneys produce erythropoietin which stimulate bone marrow to produce blood Regulates blood glucose levels 5 © STANBRIDGE UNIVERSITY 2023 5 5  10/2/2023 The Ureters Long, slender, muscular tubes Extend from kidney to urinary bladder Move urine by gravity and peristalsis Marieb, 2019 6 © STANBRIDGE UNIVERSITY 2023 6 6  10/2/2023 Anatomy of a Kidney Renal Capsule – outer cover (prevent infections from getting into kidney) Renal Cortex – outer portion Renal Medulla – contains tubes where urine is formed. Renal Pyramids – cone shaped structures (part of medulla) Renal Pelvis – collecting area for urine (tips of pyramids point to pelvis) Calyces (singular calyx) – extensions of the renal pelvis that collect urine from each pyramid and empty it into the renal pelvis. 7 © STANBRIDGE UNIVERSITY 2023 Marieb, 7 2019 7  10/2/2023 Anatomy of a Kidney Each pyramid and its surrounding Marieb, 2019 columns of cortical tissue = lobe 8 lobes in each kidney Flow of urine: 1. Urine is continuously draining from the papilla (the apex of the pyramid) into the calyces 2. Empties into the renal pelvis. 3. Urine then flows into the ureter 4. Then to the bladder for storage 5. Excreted out of the body via the urethra 8 © STANBRIDGE UNIVERSITY 2023 8 8  10/2/2023 Nephrons Structural and functional units of the kidneys > 1 million per kidney Creates filtrate from blood, from that filtrate the nephrons recover chemicals the body needs to retain and secretes into the filtrate chemicals that the body needs to get rid of Processed filtrate becomes urine which empties into the collecting ducts Components: Bowman’s capsule, proximal convoluted tubule, loop of Henle (descending and ascending), distal convoluted tubule, collecting duct (several nephrons share a collecting duct) © STANBRIDGE UNIVERSITY 2023 9 9  10/2/2023 Filtrate What is flowing through the nephron Should NOT contain large proteins or red blood cells Composed of water, NaCl, K+, HCO3, glucose (100% is reabsorbed back into the blood in the proximal convoluted tubule), amino acids (100% reabsorbed proximal convoluted tubule), creatine (a metabolite of creatine phosphate from skeletal muscles), urea © STANBRIDGE UNIVERSITY 2023 10 10  10/2/2023 Nephrons Located in the Pyramids (cortex and medulla) Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 11 11  10/2/2023 Nephron Marieb, 2019 Bowman’s capsule (glomerular capsule) Renal tubule Proximal convoluted tubule Nephron loop (formerly called loop of Henle) Distal convoluted tubule Collecting duct (shared by several nephrons) © STANBRIDGE UNIVERSITY 2023 12 12  10/2/2023 Bowman’s Capsule AKA Glomerular Capsule Capsule surrounds a tuft of specialized capillaries called the glomerulus (glomeruli plural) Glomeruli allow large amounts of protein-free fluid to pass from the blood into the capsule, this is the filtrate which the renal tubules process to eventually form urine © STANBRIDGE UNIVERSITY 2023 13 13  10/2/2023 Clinical Application Glomerular filtration rate (GFR) is the volume of filtrate formed each minute by the combined activity of all 2 million glomeruli of the kidneys Kidneys produce about 180 L of filtrate daily (all other capillary beds combined in the rest of the body produces 2-4 L) Normal GFR 120-125 ml/min https://www.kidney.org/atoz/content/gfr © STANBRIDGE UNIVERSITY 2023 14 14  10/2/2023 Renal Tubule Renal tubule has 3 parts that filtrate travels through before emptying into a collecting duct 1. Proximal convoluted tubule: filtrate leaves the glomerular capsule; great capacity for reabsorbing water and solutes from filtrate and secreting substances into it 2. Nephron loop: has descending then ascending limbs 3. Distal convoluted tubule Collecting ducts Each collecting duct receives filtrate from many nephrons Fuse together and deliver urine to the calyces of the renal pyramids © STANBRIDGE UNIVERSITY 2023 15 15  10/2/2023 Juxtaglomerular Apparatus: distal convoluted tubule (folds back) meets the afferent arteriole. Contains specialized cells that monitor and regulate blood pressure 16 © STANBRIDGE UNIVERSITY 2023 16 16  10/2/2023 Processes of Urine Formation and the Adjustment of Blood Composition 1. Glomerular filtration — “dumping filtrate into the waste container” Produces cell- and protein-free filtrate from glomerulus to Bowman’s capsule 2. Reabsorption — “reclaiming what the body needs” Selectively move substances from the filtrate back into the blood Takes place in renal tubules and collecting ducts Reclaims almost everything filtered: glucose, amino acids, 99% H2O, salt and other components Anything not absorbed here becomes urine 3. Secretion — “selectively adding to the waste container” Move substances from blood to filtrate Occurs along renal tubules and collecting ducts 4. Excretion —from tubules out of body © STANBRIDGE UNIVERSITY 2023 17 17  10/2/2023 Pathway of Filtrate 1. Afferent arteriole 2. Glomerulus & Bowman’s capsule 3. Proximal convoluted tubule 4. Nephron loop (descending then ascending) 5. Distal convoluted tubule 6. Collecting duct (shared by several nephrons) 7. Calyx; Renal Pelvis 8. Ureter 9. Urinary Bladder 10. Urethra 18 © STANBRIDGE UNIVERSITY 2023 18 18  10/2/2023 Counter-Current Multiplier in the Loop of Henle  Osmotic gradient dependent on loop of Henle  Descending limb  Permeable to water, so water gets reabsorbed into the blood  No transport of Na+, Cl–, or K+  Ascending limb  Impermeable to water  Active transport of Na+, Cl–, and K+ into the blood  To make renal medulla salty (so water leaves in descending loop) © STANBRIDGE UNIVERSITY 2023 19 19  10/2/2023 Overall Reabsorption and Secretion in the Nephron Blue= reabsorption into the blood stream Green= secretion from the blood into the nephron Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 Figure 25.16 20 20  10/2/2023 What is Urine Composed of? Water 95% Solutes 5% Urea (most): normal break down of a.a. Uric acid: nucleic acid metabolism Creatine: metabolite of creatine phosphate (energy stores in skeletal muscle) © STANBRIDGE UNIVERSITY 2023 21 21  10/2/2023 The Urinary Bladder Temporary reservoir for urine Multiple layers Mucous membrane Transitional epithelium –allows wall to stretch Rugae –folds Three-layered coat of involuntary muscle tissue 22 © STANBRIDGE UNIVERSITY 2023 22 22  10/2/2023 The Urethra Temporary reservoir for urine Multiple layers Mucous membrane Transitional epithelium –allows wall to stretch Rugae –folds Three-layered coat of involuntary muscle tissue 23 © STANBRIDGE UNIVERSITY 2023 23 23  10/2/2023 Excretion Micturition = urination = voiding Urine is formed in renal tubules → collecting duct → calyx → renal pelvis → ureter → bladder (storage) → urethra © STANBRIDGE UNIVERSITY 2023 24 24  10/2/2023 PHYSIOLOGY OF MICTURITION Storage of Urine Bladder is a reservoir that stores urine(400-600ml) Usually fills at a constant rate Accommodation: detrusor muscle is elastic and allows filling by staying relaxed, thus maintaining low bladder pressure First sensation to void: approximately half full, through sensory stretch receptors in bladder Guarding reflex: external sphincters stay contracted Postponement of voiding: bladder keeps filling Outlet pressure is higher than bladder pressure © STANBRIDGE UNIVERSITY 2023 25  10/2/2023 PHYSIOLOGY OF MICTURITION Emptying Urine Stretch receptors produce a strong sensation to void Position over the toilet: need to relax overflow muscles PFM relaxes Internal sphincter/trigone relaxes Detrusor muscle contracts No increase in intra-abdominal pressure as stream continues Outlet pressure less than bladder pressure © STANBRIDGE UNIVERSITY 2023 26  10/2/2023 VOIDING & PELVIC FLOOR MUSCLES © STANBRIDGE UNIVERSITY 2023 27  10/2/2023 CONTROL OF MICTURITION Clinical pearl: performing light stroking over sacrum can initiate urination if there is urinary hesitancy © STANBRIDGE UNIVERSITY 2023 28  10/2/2023 NORMAL BLADDER HEALTH Total number of daytime voids per 24 hours: 5-7 Amount of urine excreted each time: 8-12 oz Average time intervals between voiding: 2-3 hours optimal (up to 3-4 hrs.) Total number of nighttime voids: 0 under 65 years and 1-2 over 65 years old © STANBRIDGE UNIVERSITY 2023 29  10/2/2023 Types of Urinary Incontinence Incontinence is common but NOT normal in any population Stress incontinence Involuntary loss of urine due to increased intra-abdominal pressure during physical exertion such as laughing, sneezing, jumping, lifting, etc. Urge incontinence Urine loss accompanied by excessive urge and usually has triggers such as cold, running water, key in the lock, etc. Example of classical conditioning Mixed incontinence Combination of stress and urge incontinence Functional incontinence Unable to get to bathroom in time due to physical or mental barriers such as dementia or mobility deficits Neurogenic bladder Bladder dysfunction (flaccid or spastic) caused by neurologic damage © STANBRIDGE UNIVERSITY 2023 30 30  10/2/2023 Hormonal Regulation in the Nephrons © STANBRIDGE UNIVERSITY 2023 31 31  10/2/2023 Parathyroid Hormone Excreted from parathyroid glands Mainly acts in distal convoluted tubule (DCT) → increases body reabsorption of Ca2+ © STANBRIDGE UNIVERSITY 2023 32 32  10/2/2023 Parathyroid Hormone Marieb, 2019, Chapter 16 © STANBRIDGE UNIVERSITY 2023 33 33  10/2/2023 Antidiuretic Hormone (ADH) ADH is produced by the hypothalamus and is released by the posterior pituitary gland Released in response to increased blood solute concentration or decreased blood volume, some pain, some drugs, and low blood pressure Release inhibited by adequate hydration and by alcohol Targets the kidneys → reabsorb water from filtrate back into the blood 34 © STANBRIDGE UNIVERSITY 2023 34 34  10/2/2023 ADH Inserts aquaporins into cells of the collecting duct → more permeable to water → more water is reabsorbed back into the blood (not excreted into urine) © STANBRIDGE UNIVERSITY 2023 35 35  10/2/2023 Sodium Regulation in the Urinary System Sodium (Na+) - Sodium—primary solute in extracellular fluid Critical for normal osmotic pressure Critical to function of excitable cells Hypernatremia = high plasma sodium Hyponatremia = low plasma sodium Na+ reabsorbed in proximal tubule (70%) and in distal tubule and collecting ducts (and regulated by distal convoluted tubule and collecting duct principal cells) © STANBRIDGE UNIVERSITY 2023 36 36  10/2/2023 Sodium Reabsorption Regulated primarily by 2 hormones Aldosterone (from adrenal cortex) → ↑Na blood Atrial Natriuretic Peptide (ANP) (released by cardiac atrial cells): one function: inhibit Na+ reabsorption in collecting duct (↓Na blood) © STANBRIDGE UNIVERSITY 2023 37 37  10/2/2023 Atrial Natriuretic Peptide Reduces blood pressure and blood volume by inhibiting: ◦ Events that promote vasoconstriction ◦ Na+ and water retention ◦ Is released in the heart atria as a response to stretch (elevated blood pressure) ◦ Has potent diuretic and natriuretic effects ◦ Promotes excretion of sodium and water ◦ Inhibits angiotensin II production © STANBRIDGE UNIVERSITY 2023 38 38  10/2/2023 Major Mechanisms Controlling Aldosterone Release Marieb, 2019, Chapter 16 © STANBRIDGE UNIVERSITY 2023 39 39  10/2/2023 Sodium Regulation in the Urinary System Aldosterone: -Na+/K+ pump on basolateral membrane drives reabsorption -increase number of Na+/K+ channels on apical membrane *overall this leads to: -synthesize and retain more Na+/K+ channels → little or no Na+ leaves in the urine → increased BP (and more K+ released to filtrate) © STANBRIDGE UNIVERSITY 2023 40 40  10/2/2023 Renin - Angiotensin Blood flow to glomerulus drops Juxtaglomerular cells secrete renin in blood stream Renin (proteolytic enzyme) goes to Liver Renin converts angiotensinogen to angiotensin I Angiotensin I goes to lungs Angiotensin I converted into angiotensin II Angiotensin II goes to adrenal cortex Angiotensin II stimulates release of aldosterone © STANBRIDGE UNIVERSITY 2023 41 41  10/2/2023 © STANBRIDGE UNIVERSITY 2023 42 42  10/2/2023 Potassium Balance Controlled by how much is filtered, how much is reabsorbed, and if any is secreted Aldosterone acts to increase the amount of potassium being secreted (inverse of sodium mvmt) Elevated Plasma Potassium levels can act directly on the Adrenal Cortex to increase the release of Aldosterone © STANBRIDGE UNIVERSITY 2023 43 43  10/2/2023 REPRODUCTIVE SYSTEM Fox, Chapter 20 © Stanbridge University 2023 44 © STANBRIDGE UNIVERSITY 2023 44  10/2/2023 Objectives List the male and female gonads and gametes Understand and explain meiosis Explain genetic diversity List differences between mitosis and meiosis List differences in female reproduction in meiosis Explain main differences between sperm and ova in structure © Stanbridge University 2023 45 © STANBRIDGE UNIVERSITY 2023 45  10/2/2023 Common Features of Male and Female Reproductive Systems Both have organs called gonads that regulate reproductive functions Male gonads = testes Female gonads = ovaries Both gonads produce reproductive cells called gametes that have ½ the genetic information of the parent: Male gametes = spermatozoa (sperm) Female gametes = ova (egg) © Stanbridge University 2023 46 46  10/2/2023 Review of General Hypothalamic and Anterior Pituitary Control and Feedback Between the Gonads (Marieb, 2019) Gonadotropin-releasing hormone (GnRH): indirectly stimulates tests or ovaries via its affect on FSH and LH Follicle-stimulating hormone (FSH) and luteinizing hormone (LH): gonadotropins acting on cells in both male and female gonads where they stimulate gamete production and sex hormone secretion Sex hormones (primarily testosterone in males and estrogens and progesterone in females): act at target tissues in the body Inhibin- inhibits FSH release © Stanbridge University 2023 47 47  10/2/2023 Meiosis Meiosis: nuclear division occurring only in the gonads Sister chromatids: each chromosome has 2 identical sister chromatids, joined together by a centromere Homologous pairs of chromosomes: one member of each pair is from the parent Non-sister chromatids: ◦ One is maternal and one is paternal and are not identical. ◦ Crossing over: process in which non-sister chromatids exchange DNA (Marieb, 2019) © Stanbridge University 2023 48 48  10/2/2023 Chromosomes Of the 46 chromosomes of a fertilized egg, two (one pair) are sex chromosomes, the remaining 44 are autosomes 1. Autosomes: 22 pairs ◦ Each carries same complement of genes 2. Sex chromosomes: X and Y ◦ Not all genes are paired ◦ X chromosome - males and females ◦ Y chromosome - only males XX = girl XY = boy © Stanbridge University 2023 49 49  10/2/2023 Meiosis Male Female 46 46 chromosomes chromosomes Sperm Sperm 23 Ovum Ovum 23 chromosomes chromosomes 23 23 chromosomes chromosomes Fertilized Egg 46 chromosomes 50 © Stanbridge University 2023 50 50  10/2/2023 Meiosis https://youtu.be/qCLmR9-YY7o?si=YAazi2tL68_F2gfT © STANBRIDGE UNIVERSITY 2023 51 51  10/2/2023 Meiosis Marieb, 2019 © Stanbridge University 2023 52 52  10/2/2023 Similarities and Differences: MEIOSIS MITOSIS Sex cells (gametes) Body (somatic) cells DNA replication DNA replication 2 nuclear divisions 1 nuclear division 4 haploid cells 2 diploid cells Not genetically identical Genetically identical © Stanbridge University 2023 53 53  10/2/2023 Differences and Similarities between Mitosis and Meiosis (Marieb, 2019) © Stanbridge University 2023 54 54  10/2/2023 Differences and Similarities between Mitosis and Meiosis Marieb, 2019 © Stanbridge University 2023 55 55  10/2/2023 Meiosis in Females ◦ Meiosis I - prior to ovulation (released egg) ◦ Primary oocyte (that had been arrested in prophase I before birth) divides → Secondary oocyte (daughter cell) ◦ Meiosis II ◦ Yes sperm present ◦ Secondary oocyte divides → ovum (fertilization) ◦ No sperm present ◦ Secondary oocyte discharge → Menstruation © Stanbridge University 2023 56 56  10/2/2023 Meiosis in Females Marieb, 2019 © Stanbridge University 2023 57 57  10/2/2023 Spermatozoa (Sperm Cell) Head Acrosome - enzymes that break through wall of ovum Nucleus - 23 chromosomes Midpiece Mitochondria - produce ATPs to propel tail Tail (flagellum) Sperm are the only human cells that have flagellum Whip-like movements propel sperm 3 day life Marieb, 2019 © Stanbridge University 2023 58 58  10/2/2023 Time to Assess Learning © Stanbridge University 2023 59 59