Urinary System Vet. Anatomy and Physiology – Flashcards
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Urinary System
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Removes all soluble waste products from the blood and transports them out of the body
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Kidneys
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Make urine, Help maintain homeostasis by regulating body acid-base and fluid-electrolyte balance
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Ureter
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Continuously move urine from the kidneys to the urinary bladder by peristalsis
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Urinary Bladder
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Collects, stores, and releases urine
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Urethra
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Conducts urine out of the body, Lined with transitional epithelium
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Nephritis
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Inflammation of the kidneys
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Renal
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Refers to the kidneys
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Main ways the kidneys help maintain homeostasis
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Blood filtration, reabsorption, and secretion, fluid balance regulation, Acid-base balance regulation, Hormone production
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Fluid Balance Regulation
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Amount of urine produced is based on the body's needs under the control of antidiuretic hormone (ADH) and aldosterone
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Diuresis
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producing and passing large amounts of urine
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Oliguria
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passing small amounts of urine
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Anuria
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passing no urine
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Acid-base balance regulation
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Removes hydrogen and bicarbonate ions from the blood and excretes them in the urine
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Hormone production (kidneys)
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Influence rate of release of ADH from the posterior pituitary gland, Influence the rate of release of aldosterone, Produce erythropoietin, Produce some prostaglandins
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erythropoietin
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a hormone necessary for red blood cell production
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aldosterone
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a mineralocorticoid secreted by the cortex of the adrenal gland that regulates sodium reabsorption in the nephron and is regulated by the renin-angiotensin system
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Renin is secreted by the kidney when there is:
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low blood pressure in the afferent arteriole decreased sodium concentrations in the blood plasma a decreased osmolarity in the distal tubule stimulation of the sympathetic nerve fibers innervating the afferent arterioles
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Renin
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stimulates the production of angiotensin and aldosterone
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Angiotensin
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a vasoconstrictor that increases blood pressure
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Aldosterone
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causes the kidney to conserve sodium
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Kidney Location
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in the dorsal part of the abdomen, just ventral to and on either side of the first few lumbar vertebrae
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Horse kidney
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right is heart shaped, left is bean shaped
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Cattle kidneys
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is divided into about 12 lobes, giving it a lumpy appearance, do not have a renal pelvis
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Renal Cortex
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Outer portion of the kidney
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Renal Medulla
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Inner portion around the renal pelvis
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Hilus
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Indented area on the medial side of the kidney; area where the blood and lymph vessels, nerves, and ureters enter and leave
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Renal Pelvis
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collection point for tubular filtrate as it leaves the collecting ducts
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Calyx
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A cuplike extension of the renal pelvis into which the medullary pyramids fit, act as funnels that direct fluids into the renal pelvis
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Nephron
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Basic functional unit of the kidney, a filtering, reabsorbing, and secreting system
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Renal Corpuscle
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The first part of the nephron, it is composed of the glomerular capillaries and Bowman's capsule, filters blood at the first stage of urine production
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Glomerulus (also called Glomerular Capillaries)
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tuft of capillaries found in the renal corpuscle, main filtration mechanism of the kidney
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Bowman's Capsule
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Consists of two layers: an inner, visceral layer that lies directly on the glomerular capillaries and an outer parietal layer, Functions as a plasma filter in the process of urine formation
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Capsular Space
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The space between the visceral and parietal layers of Bowman's capsule
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Glomerular Filtrate
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The fluid that has been filtered out of the glomerular capillaries and into the capsular space
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Glomerular Filtration Rate
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The rate at which plasma is filtered into the capsular space Expressed in milliliters per minute Major factor determining GFR is blood pressure
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Proximal Convoluted Tubule (PCT)
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The first part of the tubular portion of the nephron, its lumen is a continuation of the capsular space of Bowman's capsule in the renal corpuscle, majority of tubular reabsorption takes place from the PCT
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Tubular Filtrate
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The glomerular filtrate after it has passed into the proximal convoluted tubule
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Loop of Henle
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The middle part of the tubular portion of a nephron, Has a descending part that travels from the cortex to the medulla and an ascending part that travels back to the cortex
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Distal Convoluted Tubule (DCT)
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The last tubular part of the nephron before it enters the collecting duct
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Collecting Ducts
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The tubule system that collects tubular filtrate from the distal convoluted tubules and carries it to the renal pelvis, Not a part of the nephron, Primary site of action of antidiuretic hormone (ADH)
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Renal Artery
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Branches off the abdominal portion of the aorta, enters the kidney at the hilus
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Afferent Glomerular Arterioles
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Carry blood into the glomerular capillaries of the renal corpuscle
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Glomerular Capillaries
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A continuation of the afferent arterioles; filter some of the plasma out of the blood and put it in the capsular space of Bowman's capsule
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Efferent Glomerular Arterioles
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They carry the blood that has been filtered by the glomerulus; so it contains less plasma
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Peritubular Capillaries
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Surround the nephron and converge to form venules that in turn converge to form larger veins that eventually become the renal vein
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Renal Vein
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Leaves the kidney at the hilus and joins the abdominal portion of the caudal vena cava
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(Steps of Urine Production) 1
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Blood enters the glomerulus via the afferent glomerular arteriole
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(Steps of Urine Production) 2
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High blood pressure in the glomerular capillaries forces some plasma out of the capillaries and into the capsular space of Bowman's capsule (The fluid is called glomerular filtrate)
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(Steps of Urine Production) 3
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The balance of the plasma not forced out of the glomerular capillaries leaves the glomerulus via the efferent glomerular capillaries and enters a peritubular capillary network around the rest of the nephron
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(Steps of Urine Production) 4
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When the tubular filtrate travels through the tubules of the nephron, some of its constituents are reabsorbed back into the peritubular capillaries
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(Steps of Urine Production) 5
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Waste products are secreted from the peritubular capillaries into the tubular filtrate as it travels through the tubules
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(Steps of Urine Production) 6
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The tubular filtrate reaches the collecting duct and then travels to the renal pelvis, where it is called urine
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Ureters
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Tubes that exit the kidneys at the hilus and connect to the urinary bladder near the neck of the bladder; a continuation of the renal pelvis (except in cattle)
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Ureters 3 layers
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Outer fibrous layer Middle smooth muscle layer Inner layer of transitional epithelium
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Urination
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micturition, uresis: expulsion of urine from the urinary bladder into the urethra for elimination from the body
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Muscular Sac (UB)
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Lined with transitional epithelium that stretches as the bladder becomes filled with urine
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Neck (UB)
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Extends from the sac to the urethra
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Urine accumulation (1)
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When the pressure of urine in the bladder reaches a trigger point, stretch receptors are activated
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Muscle contraction (2)
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Spinal reflex is activated that returns a motor impulse to bladder muscles to contract, which signals the sensation of having to urinate
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Sphincter muscle control (3)
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Can be controlled temporarily, When the limit is reached, urine will be released
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Urine production
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does NOT stop when the bladder is full
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Female Urethra
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Short and straight and opens on the floor of the vestibule of the vulva
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Male Urethra
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Long and curved and runs down the center of the penis
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Vas deferens and accessory reproductive glands
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enter the urethra so that spermatozoa and seminal fluid can enter it during ejaculation and be pumped out as semen
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Uremia
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Urine in the blood; waste materials, especially nitrogen wastes, build up in the blood and become toxic
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Prerenal Uremia
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decreased blood flow to the kidneys, waste materials cannot be adequately removed, ie) dehydration, shock, congestive heart failure
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Renal Uremia
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Inability of the kidneys to adequately regulate urine production due to lack of functional nephrons, so waste materials cannot be adequately removed
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Postrenal Uremia
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Associated with an obstruction that prevents urine from being expelled from the body
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Diabetes mellitus
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Insufficient insulin production by the pancreas causes high blood glucose concentrations, Excess glucose is removed in the urine, Renal threshold of glucose is the maximum amount of glucose that can be reabsorbed into the bloodstream
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Glucosuria
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glucose in the urine
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Osmotic diuresis
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abnormally high urine production
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Polydipsia
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drinking increased amounts of water
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Polyuria
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increased volume of urine production
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Diabetes insipidus
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A deficiency in antidiuretic hormone; causes the collecting ducts to not reabsorb enough water, causing polyuria
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Uroliths
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Abnormal mineral masses in the urinary system: May result from bacterial urinary tract infections Uroliths in the urinary bladder may cause hematuria (blood in the urine) and dysuria (painful urination) May lodge in the urethra and cause obstruction
