It is the urinary system that is primarily concerned with

the removal of nitrogenous wastes from the body

kidneys maintain the balance of

electrolytes
acid-base ratio
fluids

the major homeostatic organ

kidney

the kidney excretes

toxins, metabolic wastes, & excess ions in the urine

the kidney retains needed substances by

returning them to the blood

the kidney regulates

blood volume, pH, & chemical composition

Urinary System Organs

Kidneys, Urinary bladder, Ureters, Urethra

Blood flows into the kidney through

renal arteries

renal arteries

break up into the segmental arteries which enter the hilum

segmental arteries

interlobar arteries (arcuate arteries)-- cortical radiate arteries, afferent arteries

cortical radiate veins

arcuate veins -interlobar veins - renal vein- into the pelvis region

nephrons form

urine

two distinct capillary beds (two main parts of nephrons)

glomerulus
renal tubule

glomerulus (capillary knot)

a tuft of capillaries

renal tubule

begins as cup-shaped glomerular (Bowman's) capsule surrounding glomerulus

the inner visceral wall creates a porous epithelial which is an important part of the

filtration membrane

From the capsule the portions of the tubule are

-proximal convoluted tubule
-Loop of Henle
-Distal convoluted tubule

Proximal Convoluted tubule

receives filtrate from the glomerular capsule and is the site of tubular reabsorption

distal convoluted duct leads into a

collecting duct (receives urine from many nephrons)

__________ _____ give medullary pyramids their striped appearance

collecting ducts

As collecting ducts approach the renal pelvis, they fuse together and empty the urine into the

minor calyces via the papillae of the pyramids

the two capillary beds:

glomerulus
peritubular capillary bed

Urine formation is the result of three processes:

filtration, reabsorption, and secretion

filtration occurs in the

glomerulus

reabsorption and secretion begin in the

proximal convoluted tubule

Secretion involves materials either moving from the blood of the ___________ ___________ or from the tubular cells into the ________

peritubular capillaries; filtrate

chemical composition of urine

95% water and 5% solutes

Blood composition depends on 3 major factors:

diet, cellular metabolism, and urinary output

pH characteristics of urine

ranges from 4.5 to 8.0 with the average at 6.0
-diet can alter pH of urine
-bacterial infection can alter pH

specific gravity of urine is

slightly more than water, since it contains solutes

1.001 dilute urine results when

one drinks lots of water, uses diuretics, suffers from diabetes insipid us, or chronic renal failure

1.030 on the high end (concentrated) can result from

limited fluid intake, fever, kidney inflammation (pyelonephritis) or diabetes mellitus

abnormal urinary constituents

glucose
albumin

(Abnormal Urinary Constituents)

glucose due to

high carb intake or diabetes mellitus, diabetes insipidus

(Abnormal Urinary Constituents)

albumin indicative of
& due to:

abnormal permeability of the glomerular membrane
-excessive excretion, pregnancy, glomerulonephritis

(Abnormal Urinary Constituents)
-Keytone bodies

occur during starvation, or diets low in carbs

(Abnormal Urinary Constituents)
red blood cells

cystitis, irritation of the urinary tract organs
infection, inflammation

(Abnormal Urinary Constituents)
white blood cells

pus- inflammation of the urinary tract, cystitis, or pyelonephritis

(Abnormal Urinary Constituents)
casts due to

glomerulonephritis, pyelonephritis

kidney acts as a blood ______ then as a blood _________

filter; processor

ureters

drain urine from the kidneys and conduct it by peristalsis to the bladder for temporary storage

urinary bladder

receives urine from ureters and discharges it via the urethra, stores it temporarily

urethra

drains the bladder

-the superficial kidney region, lighter in color
-rich vascular supply

kidney cortex

-deep to the cortex, darker reddish-brown color
-segregated into triangular regions that have a striped appearance

medullary region

-base of each faces toward the cortex
-pointed papilla (apex) points to the innermost kidney

medullary (renal) pyramids

-areas of tissue that are more like the cortex in appearance
-segregate and dip inward between pyramids

renal columns

-extends inward from hilum
-relatively flat, basin like cavity that is continuous with the ureter (exits from hilum region)

renal pelvis

(Abnormal Urinary Constituents)
high specific gravity

diabetes mellitus, pyelonephritis

4 characteristics of urine

color variations
odor
pH
specific gravity