GU System 1 AP of the Kidneys Functions

GU System (1) A&P of the Kidneys

Functions of Urinary Systems l l l l Urine formation F & E control Acid-base balance Excretion of waste products BP regulation RBC Regulation of Ca-Phos metabolism

Sequence of urine flow l Kidneys Ureters Urinary bladder Urethra

Location of Kidneys l Retroperitoneal on either side of the vertebral column below the diaphragm

Kidney’s Gross Anatomy Structure l l Hilus is a notch located near center of medial border. It’s where blood vessels, ureter, & nerves enter/exit the kidney Renal Capsule outer covering of kidney that’s composed of strong connective tissue

Gross Anatomy (con’t) l l Renal Cortex just beneath renal capsule & contains millions of renal tubules which are part of the microscopic filtration system Medulla lies below renal cortex & contains pyramids which are triangular in shape

Gross Anatomy (con’t) l l Papillae are the pointed ends of the pyramids whose main purpose is to empty urine into calyces Calyces are cup like extensions of the renal pelvis which guide urine into the renal pelvis

Gross Anatomy (con’t) l l Renal Pelvis is an expansion of the upper end of the ureter Ureter drains urine into the bladder

Recap l Renal Capsule Renal Cortex Medulla Pyramids Papillae Calyces Renal Pelvis Ureter Bladder Urethra

Microscopic Structure l l l Glomeruli = tightly bound network of capillaries which make the Renal corpuscle Glomeruli housed inside Bowman’s Capsule R & L renal arteries branch abdominal aorta & enter kidney @ hilus

Microscopic Structure (con’t) l R & L renal arteries branch off the Abd aorta & enter the kidney @ the hilus continuing branching off until blood is delivered to glomerulus by afferent arteriole l Blood leaves glomerulus via efferent arteriole to peritubular capillary

Microscopic Structure (con’t) l Blood reaches renal veins & flows into inferior vena cava

Microscopic Structure (con’t) l l l Renal tubule becomes tightly coiled @ proximal convoluted tubule Loop of Henle distal convoluted tubule which terminates @ the collecting tubule/duct Juxtaglomerular apparatus plays a role in BP control BP determines GFR (glomeruli filtration rate)

IV. Nephron Unit Functional unit of the kidney l Responsible for filtering blood & processing urine l

Nephron Unit (con’t) l 3 major functions – – – Controlling body fluid levels by selectively +/- H 20 Assisting w/ p. H regulation of blood Removing toxic waste from the blood

V. l Hormonal Influence on Nephron Function BP d/t: – – – fluid loss b/c hemorrhage or blood loss in surgery Diaphoresis Vomiting Diarrhea NGT/GT secretion

Hormonal Influence (con’t) l l Posterior pituitary releases ADH causes distal convoluted tubules to rate of H 20 reabsorption resulting in BP

VI. l Nephron Role in UA Formation See table 10 -1, p. 411 (depending on version ) l l Glomerulus Proximal convoluted tubule Loop of Henle Distal convoluted tubule & collecting tubules

VII. Process of UA formation l l Glomerular filtration – filtration of H 2 O & blood occur in the glomerulus of Bowman’s capsule Tubular Reabsorption of H 2 O, glucose, & necessary ion back into the blood occurs in proximal convoluted tubules, Loop of Henle & distal convoluted tubules which will re-absorb needed substances back into body

Process of UA formation (con’t) l Secretion of certain ions, nitrogenous wastes & drugs occurs mainly in distal convoluted tubule – – Reverse of reabsorption Substances move from blood to filtrate

VIII. Pressure Affecting Glomerular Filtration l l l Net filtration pressure Hydrostatic pressure Osmotic pressure that develops

IX. Hormones Affecting Kidney Function (p. 410 -411, Herlihy) l Aldosterone (Aldactone) – – – Aldosterone is a hormone secreted by the adrenal cortex blood volume & also BP aldosterone = BP = blood volume Shock

Hormones Affecting Kidney Function (con’t) l Renin an enzyme which initiates a series of events called the reninangiotensin-aldosterone system – Secreted by the juxtaglomerular apparatus l Stimulated with either BP or blood volume

X. l Angiotensin II Production Renin activates angiotensinogen to form Angiotensin I – l Angiotensinogen is secreted by the liver & circulates in the blood in an inactive form An enzyme called converting enzyme acts in the pulmonary capillaries to change Angiotension I Angiotensin II

Angiotensin II Production (con’t) l l Angiotensin II stimulates the adrenal cortex to release aldosterone which stimulates the distal tubule to reabsorb sodium & water Excretion of potassium

RECAP Hormonal Influence l Renin activates Angiotensinogen (from the liver) converting enzyme (from the lungs) converts Angiotensin II

XI. Urine Composition & Characteristics l l l l Forms ~ 2 L/d 95% H 2 O 5% nitrogenous wastes & salts Influenced by several factors Slightly acidic w/ p. H of 4. 6 8. 0 Healthy urine is sterile Ammonia odor d/t break of urea What?

XII. Urine Abnormalities – Albumin l l Albuminuria Indicates possible – – – Kidney disease BP Toxicity of kidney cells from heavy metals l Give examples of heavy metals, please.

Urine Abnormalities – Glucose l l Glycosuria Indicates – l Blood glucose level rises above renal threshold – l Blood sugar (glucose) level Point @ which kidney tubules can no longer reabsorb Glucose spills into the urine

Urine Abnormalities – Erythrocytes l l Hematuria May indicate – – – Infection Tumors Kidney dz or calculi (stone)

Urine Abnormalities – Ketone Bodies l l Ketonuria or ketoaciduria occurs when there is an excessive amount of fatty acid which are oxidized/ catabolized Seen with – – – DM Starvation Anorexia Nervosa

Urine Abnormalities – Leukocytes l Presence of WBCs (leukocytes) occurs in the presence of an infection or inflammatory process in the urinary tract