module 10—urinary system

Why do doctors often ask you for a urine sample?

diagnose UTIs

evaluate symptoms

monitor chronic conditions

routine check ups

pregnancy

pre surgery evaluation

A urinalysis (three things)…

screens for diseases

detects infections

diagnose a medical condition

Urochrome definition

yellow pigment

What is this urine showing

hydrated

What is this urine showing?

dehydrated

What is the volume for normal urine output?

1-2 L/day

What is the volume for polyuria output?

>2.5 L/day

What is the volume for oliguria output?

300-500 mL/day

What is the volume for anuria output?

<50 mL/day

Causes of polyuria

diabetes mellitus

diabetes insipidus

excess caffeine or alcohol

kidney disease

certain drugs (ie. diuretics)

sickle cell anemia

excessive water intake

Causes for oliguira

dehydration

blood loss

diarrhea

cardiogenic shock

kidney disease

enlarged prostate

Causes for anuria

kidney failure

obstruction (ie. kidney stone or tumor)

enlarged prostate

Urinary system functions

removes wastes from blood

maintains concentration of water and electrolytes

regulates pH and blood pressure

maintains homeostasis

Urine composition

photo

A urinalysis involves checking the…

appearance, concentration, and content of urine

During a urinalysis, this includes checking for…

clarity

color

odor

pH level

substances that are not normally in urine (ie. blood, protein, glucose, ketones, bilirubin)

cells, crystals, and casts

bacteria or other germs

Normal pH that a urinalysis assesses…

minimum of 4.5

maximum of 8.0

Diet can influence pH of urine, what are examples of this?

foods that lower pH; meats

foods that raise pH: citrus fruits, vegetables, dairy products

Chronically high or low pH of urine can lead to disorders such as…

development of kidney stones or osteomalacia

Specific gravity definition

measure of the quantity of solutes per unit volume of a solution

The specific gravity of urine is…

always greater than pure water

The presence of leukocytes in urine may indicate a…

urinary tract infection

What is released by leukocytes and is detected in a urinalysis?

leukocyte esterase

If leukocyte esterase is detected in the urine, it can be taken as indirect evidence of a…

urinary tract infection (UTI)

Protein does not normally…

leave the glomerular capillaries

What is the normal range of protein in urine

10 mg/100 mL

If excessive protein is detected in urine, it usually means the…

glomerulus is damaged and is allowing protein to “leak” into the filtrate

Ketones are…

byproducts of fat metabolism

Finding ketones in the urine suggests that the body is…

using fat as an energy source in preference to glucose

Nitrates (NO3-) occur…

normally in the urine

Gram negative bacteria metabolize…

nitrate (NO3-) into nitrite (NO2-)

The presence of nitrite (NO2-) in the urine is indirect evidence of…

infection

There should be no _____ found in the urine

blood

Even though blood should not be found in urine, it may sometimes appear in urine samples as a result of…

menstrual contamination

Functions of the kidneys

• filters 200 liters of blood daily

  • allows toxins, metabolic wastes, and excess ions to leave the body in urine

• regulate volume and chemical makeup of the blood

• maintain the proper balance between water, salts, acids, and bases

Other renal functions

• gluconeogenesis during prolonged fasting

• production of rennin to help regulate blood pressure and erythropoietin to stimulate RBC production

• activation of vitamin D

Label the figure

photo

The urinary system consists of a…

pair of kidneys which filter the blood

Ureters transport urine from the…

kidneys to the bladder

The urinary bladder stores…

urine

The urethra transports…

urine outside the body

Label the figure

photo

Label the figure

photo

Renal arteries attach to the…

aorta

Renal veins attach to the…

inferior vena cava

Blood enters the kidneys where it…

moves into smaller arterioles

Diffusion removes substances from the…

blood and collects into a filtrate

The filtrate is removed in…

urine

How many renal pyramids does each kidney have?

7-18

Each renal pyramid contains thousands of…

nephrons

Label the figure

photo

Nephrons are the…

structural and functional units that form urine

Nephrons consists of…

glomerulus

glomerular (bowman’s) capsule

renal corpuscle

glomerular endothelium

Glomerulus definition

a tuft of capillaries associated with a renal tubule

Glomerular (Bowman’s) capsule definition

blind, cup-shaped end of a renal tubule that completely surrounds the glomerulus

Renal corpuscle definition

the glomerulus and its bowman’s capsule

Glomerular endothelium definition

fenestrated epithelium that allows solute rich, virtually protein free filtrate to pass from the blood into the glomerular capsule

The nephron is the…

functional unit of the kidney

Vessels loop around tubes, allowing for…

diffusion from the blood into the tubules

Renal function

photo

Label the figure of nephron anatomy

photo

Label the figure of glomerular filtration

photo

Label the figure

A: glomerulus

B: bowman’s capsule

C: proximal convoluted tubule

D: distal convoluted tubule

E: collecting duct

F: peritubular capillary network

G: vein

H: artery

X: afferent arteriole

Y: efferent arteriole

What is the difference between reabsorption and secretion?

reabsorption moves water and solutes from the filtrate back into the blood

secretion transfers waste from the blood directly into the nephron to be excreted

Secretion definition (urinary system)

removes substances from the blood and collects as urine

Reabsorption definition (urinary system)

moves water, glucose, or other substances back into the blood

Filtration, reabsorption, and secretion flow

photo

The renal corpuscle consists of…

glomerulus

bowman’s (glomerular) capsule

The glomerulus is a…

high pressure capillary bed between afferent and efferent arterioles

Bowman’s capsule surrounds the glomerulus to form a…

lumen

Bowman’s capsule surrounds the glomerulus to form a lumen and…

captures and directs this filtrate to the proximal convoluted tubule (PCT)

Glomerular filtration rate (GFR) definition

volume of filtrate formed by both kidneys per minute

The heart pumps about…

5 L blood/min under resting conditions

How much blood enters the kidneys to be filtered?

~20% or 1 L

On average, ____ of the filtrate is returned to circulation by _______ so that only about _______ of urine is produced per day

99%

reabsorption

1-2 L

Pressure in the renal corpuscle

photo

Blood enters the kidney via…

afferent arteriole

The glomerulus is enclosed by…

bowman’s capsule

Bowman’s capsule connects to the…

proximal convoluted tubule

Blood exits the kidney via…

efferent arteriole

The afferent arteriole brings in blood from the…

aorta

The efferent arteriole brings matter to the…

tubules

Renal corpuscle

photo

Parietal layer definition (urinary system)

the outermost part of bowman’s capsule

The parietal layer of bowman’s capsule is composed of…

simple squamous epithelium

The visceral layer of bowman’s capsule contains…

podocytes

Podocytes definition

uniquely shaped cells extending pedicels to cover the glomerular capillaries

Podocytes have…

projections that interdigitate to form filtration slits, leaving small gaps between the digits to form a sieve

______ of the plasma filters between these sieve-like fingers to be captured by ______ _______ and funneled to the ______ ______ _____ (___)

10-20%

bowman’s capsule

proximal convoluted tubule (PCT)

The filtration membrane is a…

filter that lies between the blood and the interior of the glomerular capsule

The filtration membrane is composed of three layers…

fenestrated endothelium of the glomerular capillaries

visceral membrane of the glomerular capsule (podocytes)

basement membrane composed of fused basal laminae of the other layers

Filtration membrane

refer to slide for process

Filtration membrane (detailed)

photo

Fenestrations of bowman’s capsule prevent…

filtration of blood cells or large proteins

Fenestrations of bowman’s capsule allow…

most other constituents through

Fenestrations of bowman’s capsule are ______ ______ so they repel _______ ______ _______ and allow ______ _______ _______ to pass more readily

negatively charged

negatively charged substances

positively charged substances

Basement membrane of bowman’s capsule permits…

very rapid movement of filtrate from capillary to capsule through pores

Basement membrane of bowman’s capsule prevents…

filtration of medium to large proteins such as globulins

Mesangial cells of bowman’s capsule are found in the…

filtration membrane

Mesangial cells contract to…

help regulate the rate of filtration of the glomerulus