The Urinary System

The Urinary System

Chapter 16

Waste Excretion

• Chemical reactions in the body result in waste products that may be potentially harmful, therefore must be eliminated.

Methods of elimination:• ______________ system, _________ system,

__________________ system, sweat

• The urinary system is the most important route of waste-product removal in the body. It removes nearly all the soluble waste products from blood and transports out of the body.

–Also removes excess water from the body.

The Urinary SystemThe Urinary SystemParts of urinary system:Parts of urinary system:

• Two ________________Two ________________– Make urine and carry out other vital Make urine and carry out other vital

functions.functions.

• Two ________________Two ________________– Carry urine to the urinary bladder.Carry urine to the urinary bladder.

• Urinary ______________Urinary ______________– Collects, stores and releases urine.Collects, stores and releases urine.

• One _______________One _______________– Carries urine from the body to the Carries urine from the body to the

external environment. external environment.

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Terminology

• nephro/reno = kidney

• __________________- the study of the kidney.

• _______________ or _______________(CS)- producing large amounts of urine

• __________________- passing small amounts of urine

• _________________- no urine is passed from the body

• _________________- difficult urination

• _________________- blood in urine

• _________________- increased urinary frequency

Kidney Function

• Must maintain homeostasis through a variety of processes.

– ___________ filtration, reabsorption, and secretion• Blood is filtered, useful substances are returned to

circulation, and waste products are secreted.

– __________ balance regulation• Makes sure body has enough water to maintain healthy

environment.

– _____________ regulation• Ability to remove hydrogen and bicarbonate ions from

blood.

– _____________ regulation• Na+, K+, Cl- • can be fatal outside of normal levels

– _____________ production• Kidneys produce __________________- hormone

necessary for red blood cell production • Kidneys are influenced by Antidiuretic Hormone

(posterior pituitary) and Aldosterone (adrenal cortex)

Location of the kidneys

• In ___________ part of abdomen, ventral to and on either side of first few lumbar vertebrae.

• Are __________________ to the abdominal cavity and are considered outside abdominal cavity.

• In most domestic animals, right kidney is slightly more cranial than left.

• Perirenal ________surrounds and helps protect from other organs.

Gross Anatomy of the Kidney

• Bean shaped and covered by fibrous connective tissue capsule.

• Reddish brown in color

• Generally a smooth surface– Cattle have multiple lobed kidney which gives it a lumpy appearance

• ___________ : indented area on medial side of kidney – Ureters, nerves, blood and lymph vessels enter/leave kidney

• Renal Pelvis: funnel-shaped area inside hilus– Forms beginning of ureter – Lined with stretchable _______________ epithelium – cattle lack a renal pelvis

Gross Anatomy of the Kidney

• __________ - outer portion of the kidney.

– Rough granular appearance, reddish brown in color

• __________ - inner portion around the renal pelvis.

– Smooth appearance– rays extend toward cortex– Varies with species can be

multipyramidal (multilobar) or unipyramidal (unilobar).

• ___________ - funnel-like extension(s) of the renal pelvis that the medullary pyramid(s) drain into.

– Calyces funnel fluid into renal pelvis, with the exception of cattle

Microscopic Anatomy of the

Kidney

• _____________- basic functional unit of the kidney whose job is to filter, reabsorb and secrete.

– Smallest part of the kidney– Number varies per kidney and species

• 1 million in human, sheep, pigs• 200,000 in cat

– Composed of:

• Renal Corpuscle– Bowman’s capsule and

glomerulus

• Proximal Convoluted Tubule (PCT)

• Loop of Henle

• Distal Convoluted Tubule (DCT)

• Located in cortex of kidney.

• Function is to filter blood in first stage of urine production.

– This filtrate is called GLOMERULAR FILTRATE

• Made up of _______________ (tuft of capillaries), and _______________ capsule (double walled capsule that surrounds the glomerulus).

– Bowman’s capsule has inner visceral layer and outer parietal layer. These layers are composed of simple squamous epithelium.

• Space between these two layers is known as the capsular space and is continuous with the proximal convoluted tubule.

Renal Corpuscle

Proximal Convoluted Tubule

(PCT)

• Continuation of the capsular space of the Bowman’s capsule.

• Longest part of the tubular system of the nephron.

– Glomerular filtrate becomes _____________ filtrate (primitive urine).

– twisted

• Epithelial cells are cuboidal and have a brush border on lumen side that increases the surface area.

Loop of Henle• Continued from PCT

• If long, may descend into medulla of the kidney and then ascend back to cortex.

• _________________ portion– Cuboidal epithelial cells like

PCT with brush border

• Epithelium flattens to simple squamous epithelial cells and loses brush border

• ________________ loop wall becomes thicker again– Cuboidal , but with NO brush

border

Distal Convoluted Tubule (DCT)

and Collecting Ducts

• DCT is a continuation of ascending portion of Loop of Henle

– Not as twisted as PCT– Cubiodal epithelium w/o brush border

• The nephron ends with the DCT.

• The DCT from all nephrons empty into a series of _____________ __________ which carry tubular filtrate through the medulla, calyces, renal pelvis, and then ureter.

• The DCT and Collecting Ducts are the sites of action for:– Antidiuretic Hormone (ADH)– Regulation of K+– Acid-base balance

Nerve Supply to the Kidneys

• Supplied by _________________ portion of autonomic nervous system.– Sympathetic stimulation

decreases the diameter of blood vessels leading to the kidney

• Controls the blood flow through the glomerular capillaries.

Blood Supply to the Kidneys

Blood Supply

• ____________ artery

– Branches off of aorta and enters kidney at hilus

– Divides smaller and smaller into afferent glomerular arterioles

• _____________ glomerular arterioles

– Carry blood into the glomerular capillaries of the renal corpuscle.

• ______________ capillaries

– Continuation of afferent glomerular arterioles.

– Filter plasma from blood in capsular space – called glomerular filtrate.

– Only place in body where blood that enters and leaves capillaries is still oxygenated blood.

Blood Supply

• ______________ glomerular arterioles

– Receive blood (oxygenated) from glomerular capillaries

– Divide into peritubular capillaries

• _______________ capillaries

– Surround nephron and converge to form venules then become renal vein.

– Oxygen transfer occurs here.– Usable substances are removed

from tubular filtrate and reabsorbed. – Other waste substances are

secreted into filtrate here as well.

• ______________ vein

– Leaves kidney at hilus and joins abdominal portion of the caudal vena cava.

• Purest blood in body.