Urinary System Vet. Anatomy and Physiology Flashcard

Flashcard maker : Josephine Mack
Urinary System
Removes all soluble waste products from the blood and transports them out of the body
Kidneys
Make urine, Help maintain homeostasis by regulating body acid-base and fluid-electrolyte balance
Ureter
Ureter
Continuously move urine from the kidneys to the urinary bladder by peristalsis
Urinary Bladder
Collects, stores, and releases urine
Urethra
Conducts urine out of the body, Lined with transitional epithelium
Nephritis
Inflammation of the kidneys
Renal
Refers to the kidneys
Main ways the kidneys help maintain homeostasis
Blood filtration, reabsorption, and secretion, fluid balance regulation, Acid-base balance regulation, Hormone production
Fluid Balance Regulation
Amount of urine produced is based on the body’s needs under the control of antidiuretic hormone (ADH) and aldosterone
Diuresis
producing and passing large amounts of urine
Oliguria
passing small amounts of urine
Anuria
passing no urine
Acid-base balance regulation
Removes hydrogen and bicarbonate ions from the blood and excretes them in the urine
Hormone production (kidneys)
Influence rate of release of ADH from the posterior pituitary gland, Influence the rate of release of aldosterone, Produce erythropoietin, Produce some prostaglandins
erythropoietin
a hormone necessary for red blood cell production
aldosterone
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
Renin is secreted by the kidney when there is:
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
Renin
stimulates the production of angiotensin and aldosterone
Angiotensin
a vasoconstrictor that increases blood pressure
Aldosterone
causes the kidney to conserve sodium
Kidney Location
in the dorsal part of the abdomen, just ventral to and on either side of the first few lumbar vertebrae
Horse kidney
right is heart shaped, left is bean shaped
Cattle kidneys
is divided into about 12 lobes, giving it a lumpy appearance, do not have a renal pelvis
Renal Cortex
Renal Cortex
Outer portion of the kidney
Renal Medulla
Inner portion around the renal pelvis
Hilus
Indented area on the medial side of the kidney; area where the blood and lymph vessels, nerves, and ureters enter and leave
Renal Pelvis
collection point for tubular filtrate as it leaves the collecting ducts
Calyx
A cuplike extension of the renal pelvis into which the medullary pyramids fit, act as funnels that direct fluids into the renal pelvis
Nephron
Basic functional unit of the kidney, a filtering, reabsorbing, and secreting system
Renal Corpuscle
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
Glomerulus (also called Glomerular Capillaries)
tuft of capillaries found in the renal corpuscle, main filtration mechanism of the kidney
Bowman’s Capsule
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
Capsular Space
The space between the visceral and parietal layers of Bowman’s capsule
Glomerular Filtrate
The fluid that has been filtered out of the glomerular capillaries and into the capsular space
Glomerular Filtration Rate
The rate at which plasma is filtered into the capsular space
Expressed in milliliters per minute
Major factor determining GFR is blood pressure
Proximal Convoluted Tubule (PCT)
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
Tubular Filtrate
The glomerular filtrate after it has passed into the proximal convoluted tubule
Loop of Henle
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
Distal Convoluted Tubule (DCT)
The last tubular part of the nephron before it enters the collecting duct
Collecting Ducts
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)
Renal Artery
Branches off the abdominal portion of the aorta, enters the kidney at the hilus
Afferent Glomerular Arterioles
Carry blood into the glomerular capillaries of the renal corpuscle
Glomerular Capillaries
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
Efferent Glomerular Arterioles
They carry the blood that has been filtered by the
glomerulus; so it contains less plasma
Peritubular Capillaries
Surround the nephron and converge to form venules that in turn converge to form larger veins that eventually become the renal vein
Renal Vein
Leaves the kidney at the hilus and joins the abdominal portion of the caudal vena cava
(Steps of Urine Production) 1
Blood enters the glomerulus via the afferent glomerular arteriole
(Steps of Urine Production) 2
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)
(Steps of Urine Production) 3
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
(Steps of Urine Production) 4
When the tubular filtrate travels through the tubules of the nephron, some of its constituents are reabsorbed back into the peritubular capillaries
(Steps of Urine Production) 5
Waste products are secreted from the peritubular capillaries into the tubular filtrate as it travels through the tubules
(Steps of Urine Production) 6
The tubular filtrate reaches the collecting duct and then travels to the renal pelvis, where it is called urine
Ureters
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)
Ureters 3 layers
Outer fibrous layer

Middle smooth muscle layer

Inner layer of transitional epithelium

Urination
micturition, uresis: expulsion of urine from the urinary bladder into the urethra for elimination from the body
Muscular Sac (UB)
Lined with transitional epithelium that stretches as the bladder becomes filled with urine
Neck (UB)
Extends from the sac to the urethra
Urine accumulation (1)
When the pressure of urine in the bladder reaches a trigger point, stretch receptors are activated
Muscle contraction (2)
Spinal reflex is activated that returns a motor impulse to bladder muscles to contract, which signals the sensation of having to urinate
Sphincter muscle control (3)
Can be controlled temporarily, When the limit is reached, urine will be released
Urine production
does NOT stop when the bladder is full
Female Urethra
Short and straight and opens on the floor of the vestibule of the vulva
Male Urethra
Long and curved and runs down the center of the penis
Vas deferens and accessory reproductive glands
enter the urethra so that spermatozoa and seminal fluid can enter it during ejaculation and be pumped out as semen
Uremia
Urine in the blood; waste materials, especially nitrogen wastes, build up in the blood and become toxic
Prerenal Uremia
decreased blood flow to the kidneys, waste materials cannot be adequately removed, ie) dehydration, shock, congestive heart failure
Renal Uremia
Inability of the kidneys to adequately regulate urine production due to lack of functional nephrons, so waste materials cannot be adequately removed
Postrenal Uremia
Associated with an obstruction that prevents urine from being expelled from the body
Diabetes mellitus
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
Glucosuria
glucose in the urine
Osmotic diuresis
abnormally high urine production
Polydipsia
drinking increased amounts of water
Polyuria
increased volume of urine production
Diabetes insipidus
A deficiency in antidiuretic hormone; causes the collecting ducts to not reabsorb enough water, causing polyuria
Uroliths
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

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