Veterinary Nurses Clinical Anatomy and Physiology PDF

Clinical Anatomy and Physiology ​ for Veterinary Nurses URINARY SYSTEM WEEK 10 PART A Lowri Bennett BSc Hons RVN [email protected]  Outline of today  Why do you need to know this?  Overview of the urinary system and its functions  Location...

Clinical Anatomy and Physiology ​ for Veterinary Nurses URINARY SYSTEM WEEK 10 PART A Lowri Bennett BSc Hons RVN [email protected]  Outline of today  Why do you need to know this?  Overview of the urinary system and its functions  Location and anatomy of the kidneys  Anatomy of the nephron  Renal histology  The adrenal gland  Blood pressure  The ureters, bladder and urethra  Micturition  Urine composition and urinalysis  Why do you need to know this?  Urinary problems are commonly encountered in practice. Diseases such as UTIs, kidney failure and incontinence are common.  Understanding diagnostic tools  You may be asked by owners what is ‘normal’ with regards to urine and urination  You need to know what is normal to recognise abnormalities  You also need to know why certain treatments are needed for urinary problems, and how patients are monitored  Outline of today  Why do you need to know this?  Overview of the urinary system and its functions  Location and anatomy of the kidneys  Anatomy of the nephron  Renal histology  The adrenal gland  Blood pressure  The ureters, bladder and urethra  Micturition  Urine composition and urinalysis The urinary system  Comprises of:  The kidneys  The ureters  The bladder  The urethra Functions of the urinary system To regulate the chemical To remove waste Secretes the composition and products (e.g. hormone volume of body urea) and excess ‘erythropoietin’ fluids water (‘osmoregulation’)  Outline of today  Why do you need to know this?  Overview of the urinary system and its functions  Location and anatomy of the kidneys  Anatomy of the nephron  Renal histology  The adrenal gland  Blood pressure  The ureters, bladder and urethra  Micturition  Urine composition and urinalysis The kidneys  Two kidneys in the body  ‘Bean’ shaped in most mammals – Apart from the right kidney of a horse.  Located in the abdomen (right is slightly more cranial than left)  Retroperitoneal position  The kidneys  The concaved area of kidney is known as the Hilus. This is where the main blood vessels that supply the kidney and the ureter enter and leave the organ. HILU  The renal arteries branch off the aorta and S to supply the kidneys with oxygenated blood.  The renal veins connect with the inferior/caudal vena cava to remove deoxygenated blood from the organ to return to the heart.  The kidneys receive around 20-25% of cardiac output while at rest.  Pelvis Anatomy of the kidneys Capsule – protective connective Pyramid tissue layer Cortex – outermost layer of kidney (contains renal corpuscles (glomeruli) Click to add text and convoluted tubules of the nephrons) Medulla – innermost layer of kidney – split into renal pyramids in some Renal species (contains collecting ducts and Papilla loops of Henle of the nephrons) Renal columns  The Renal Pelvis Minor calyx: A small, cup-shaped chamber that surrounds the renal papilla of a renal pyramid and collects urine from it Major calyx: A larger calyx that's formed by the merging of several minor calyces Urine flows from the minor calyces into the major calyces, and then into the renal pelvis. The renal pelvis is a funnel-shaped structure that drains urine out of the kidney through the ureter  Outline of today  Why do you need to know this?  Overview of the urinary system and its functions  Location and anatomy of the kidneys  Anatomy of the nephron  Renal histology  The adrenal gland  Blood pressure  The ureters, bladder and urethra  Micturition  Urine composition and urinalysis The nephron  Nephrons are the functional units of the kidney  Filter the blood, removing waste products, toxins and drugs and produce urine.  They are microscopic in size  Number of nephrons:  Equine – over 1 million nephrons  Canine – 400,000  Feline and birds – 200,000  Rabbits – 170,000  Areas of the nephron Nephrons are essentially long tubes divided into different parts:  Glomerulus  Bowman’s capsule  Proximal convoluted tubule  Loop of Henle  Distal convoluted tubule  Collecting duct  Glomerulus and Bowman’s Capsule  Bowman’s capsule is this cup- Efferent arteriole shaped structure with a bundle of capillaries (tiny blood vessels) inside (Glomerulus)  Together these make the renal corpuscle  Blood arrives in the capillaries under high pressure  Water and small molecules forced out of blood into capsule  This forms the ‘glomerular Afferent arteriole filtrate’  Proximal Convoluted Tubule (PCT) After entering the capsule, fluid drains into the PCT Most of resorption happens here:  Na, K and Cl (Sodium, potassium and Chloride)  Glucose, amino acids  Calcium (stimulated by calcitriol)  Water and other nutrients Waste products excreted from blood The Loop of Henle  Regulates how much and how concentrated the urine is  Flows into the descending loop, then the ascending loop  Water is removed along the way, amount depends on how hydrated the animal is.  The length of a loop of Henle will depend on the breed.  The distal convoluted tubule (DCT) Primary functions:  Fine-tunes the composition of filtrate  Critical role in regulating electrolytes, acid-base balance and blood pressure  Works under hormonal control for precision Reabsorbed into the blood (Principal cells):  Ca (Calcium) – Controlled by the parathyroid hormone (PTH) from the parathyroid glands  Na+ (sodium) - Controlled by the hormone ‘aldosterone’ from the adrenal glands Secretion (Intercalated cells):  K + (potassium) secreted into urine, regulated by aldosterone  H + (hydrogen) ions secreted into urine (Regulation of blood pH)  Collecting duct (CD)  Final part of the nephron, connects the DCT to the renal pelvis and ureter.  Cuboidal and columnar epithelium.  Principal and Intercalated cells are also found in the CD.  Aldosterone released from the adrenal gland will absorb sodium and secrete potassium to maintain electrolyte balance.  Antidiuretic Hormone (ADH) from posterior pituitary gland increases water absorption into the blood resulting in concentrated urine during dehydration.  Outline of today  Why do you need to know this?  Overview of the urinary system and its functions  Location and anatomy of the kidneys  Anatomy of the nephron  Renal histology  The adrenal gland  Blood pressure  The ureters, bladder and urethra  Micturition  Urine composition and urinalysis Renal Histology Renal Histology Cells: - Proximal convoluted tubule: Simple cuboidal and columnar epithelium with microvilli. - Loop of Henle: Lined with simple squamous epithelium. - Distal convoluted tubule Simple cuboidal epithelium (no microvilli like in the PCT). - Collecting tubule Simple cuboidal epithelium (no microvilli like in the PCT).