The Urinary System

OVERVIEW

https://www.youtube.com/watch?v=lfGYd1wrTgE&list=PLR6x-Lyq3PY7GVj1h5mFQ9Y9mMj_jnmWQ

Bozeman https://www.youtube.com/watch?v=qfWx8

msgHqM

Function

1. Remove nitrogenous wastes2. Maintain electrolyte(ions), pH

(acid-base), and fluid balance of blood

3. Homeostatic organ4. Acts as blood filter5. Release hormones

What does this mean?It regulates the water and salt in the body. So… whatever excess we have, it helps us get rid of it.

Kidneys as Filters

• Average kidney filtration rate= 180 liters (50 gal) of blood/day

• 178-179 liters are reabsorbed back into blood

Nitrogenous Wastes

ammonia

urea

uric acid

Organs of the

Urinary System

Organs of the

Urinary System

kidneys

ureters

urinary bladder

urethra

Check your kidney diagram

renal capsule

renal cortex

renal medulla

renal pelvis

renal pyramids

ureter

Kidney AnatomyKidney

Anatomy

http://www.youtube.com/watch?v=cc8sUv2SuaY&feature=related

Kidney AnatomyKidney

Anatomy

renal artery

renal vein

nephronnephronNephron = functional unit of kidney

Each kidney contains > 1,000,000 nephrons.

urine

blood

filtration

tubular reabsorption and secretion

Nephron Functioning

Nephron Functioning

“refreshed” blood

vein

artery

afferent arteriole

efferent arteriole

glomerulus

peritubular capillaries

Bowman’s capsule

proximal convoluted tubuledistal convoluted tubule

loop of Henle

collecting duct

renal cortex

renal medulla

Collecting duct

Loop of Henle

PCT

DCTGlomerulus

Each kidney contains over 1 million nephrons and thousands of collecting ducts

Glomerular Filtration

Glomerular Filtration

afferent arteriole

glomerulus

efferent arteriole

Bowman’s capsule

Filters blood; proteins can’t pass through

Add ARROWS TO Figure 15-3: Diagram of a NEPHRON.

Label NEPHRON diagram

Composition of Glomerular Filtrate (1,15)

• Water• Small Soluble Organic

Molecules (i.e. amino acids, glucose)

• Mineral Ions

Proximal Convoluted Tubule

(13)

Reabsorbs: water, glucose, amino acids, and sodium.

Loop of Henle(10)

Descending – reabsorbs H2OAscending – reabsorbs Na+ and Cl-

Distal Convoluted Tubule(12)

ABSORBS - H20Ca++PO4 (phosphates)Na+

SECRETES - H+ K+

Collecting Duct(11)

Allows for the osmotic reabsorption of water.

Urine

Water- 95%Nitrogenous waste:

• urea• uric acid• Creatinine (waste product of

muscle cell metabolism)

Ions:• sodium• potassium• sulfate• phosphate

Urinary BladderUrinary Bladder

uretersinternal sphinctersexternal

sphinctersurethra

Draw &

label

Internal urethral sphincter:• Smooth muscle• Involuntary control

External Urethral sphincter:• Skeletal muscle• Voluntary control

Sphincter Muscles on Bladder

When bladder fills with 200 ml of urine, stretch receptors transmit impulses to the CNS and produce a reflex contraction of the bladder (PNS)

Diuresis

Distension of the

Urinary Bladder

Micturition – voiding; eliminating urine

Why do doctors ask for a urine sample?       

Urinalysis

characteristics:• smell- ammonia-like• pH- 4.5-8, ave 6.0• specific gravity– more than 1.0; ~1.001-

1.003 • color- affected by what we eat: salty foods,

vitamins

odor- normal is ammonia-like

diabetes mellitus- smells fruity or acetone like due to elevated ketone levels

diabetes insupidus- yucky

asparagus---

Odor

pH- range 4.5-8 ave 6.0

vegetarian diet- urine is alkaline

protein rich and wheat diet - urine is acidic

Color- pigment is urochromeYellow color due to metabolic breakdown of hemoglobin (by bile or bile pigments)

Beets or rhubarb- might give urine a pink or smoky color

Vitamins- vitamin C- bright yellow

Infection- cloudy

Color

 Glucose- when present in urine condition called glycosuria (nonpathological) [glucose not normally found in urine]

Indicative of:• Excessive carbohydrate intake• Stress• Diabetes mellitus

Abnormal Contents of Urine