BIOl215 Urinary System

Functions of Urinary System

1. Excretion

2.Regulation of Blood Vol. and BP

3. Regulation of blood solute concentrations.

4. Regulation of extracellular fluid pH.

5. Stimulation of RBC synthesis

6. Activation of Vit. D

Kidney Location

Retroperitoneal (behind peritoneum)

Which kidney is slightly lower

right kidney

Renal Capsule is made of

Fibrous connective Tissue

Peri-renal fat

engulfs renal capsule and acts as cushioning/protection

Renal Fascia is a

thin layer of loose connective tissue - anchors kidneys to abdominal wall

The Hilum

Opens into renal sinus

Renal Sinus is a

cavity filled with fat and loose connective tissue

what surrounds the renal sinus

Medulla

Outer area of kidney is called

Cortex

Cortical tissue that extends into medulla is

Renal Columns

Apex of Renal Pyramids is

Renal Papilla

Renal pelvis is formed by

Major Calyces

What exits at the hilum and connects to the urinary bladder?

Ureter

What are the parts of the nephron

•Renal corpuscle

•Bowman's capsule

•Glomerulus

•Proximal convoluted tubule

•Loop of Henle

•Distal convoluted tubule

Pathway of Urine from nephron

collecting ducts -> papillary ducts -> minor calyces -> major calyces ->renal pelvis

What does the Loop of Henle do

Conserve water and solutes

Renal corpuscle function

Filter Blood

PCT purpose

Returns filtered substances to the blood

DCT Purpose

DCT rids the blood of additional wastes

Juxtamedullary Nephrons are

Near cortical medullary border

Loop of Henle extends deep into medulla

Cortical Nephrons are

Near periphery of cortex

Loop of Henle does not extend deep into medulla

Where do Renal arteries branch from

Abdominal Aorta

Where do Segmental arteries branch from

Renal

Where do Interlobar arteries ascend from

ascend from renal column towards cortex

Where do Arcuate arteries branch and arch from

Base of the Pyramids

Where do Interlobular arteries project

Project at cortex and give rise to afferent arterioles

Where do Afferent Arterioles supply blood to

Afferent arterioles supply blood to the glomerulus

Where do Efferent arterioles exit

The renal corpuscle

What forms a plexus around Proximal and Distal tubules

Peritubular Capillaries

What are the specialized parts of peritubular capillaries

Vasa Recta

3 Steps of Urine formation

1. filtration

2. tubular reabsorption

3. tubular secretion

What is the smallest structural component capable of producing urine

The Nephron

Layers of Bowmans Capsule are

Outer parietal layer

Inner visceral layer

Glomerulus is a

network of capillaries

What supplies blood to the Glomerulus

afferent arterioles

What drains the glomerulus?

efferent arteriole

What is the sight of Renin production

juxtaglomerular apparatus

What is the juxtaglomerular apparatus composed of

macula densa and juxtaglomerular cells

What does the Macula Densa do

•Regulates blood pressure and filtrate formation

What is the Parietal Layer made up of

simple squamous epithelium

What is the Visceral Layer made up of

podocytes

What is the window-like openings of the glomerular capillaries called

Fenestrae

Filtration slits are

gaps between the cell processes of the podocytes

Filtration membrane is made up of

Fenestrated/Capillary endothelium, basement membrane and podocytes

Where does the first stage of Urine Formation occur

Filtration Membrane

What can not fit through the Fenestra

Large proteins and Blood cells

Where do collecting ducts form

where many distal tubules come together

How much protein is found in urine

very little

Filtration Pressure

Pressure gradient responsible for filtration

GCP (Glomerular capillary pressure) says that

BP inside the capillary moves fluid OUT OF the capillary and INTO Bowmans capsule

CHP (Capsule hydrostatic pressure) says that

pressure of filtrate already in the lumen tends to move fluid INTO the capillary

BCOP (Blood colloid osmotic pressure) says that

osmotic pressure is caused by proteins in blood

Acute Glomerulonephritis means the filtration membrane becomes

More permeable and proteins enter the filtrate

What is the result of Acute Glomerulonephritis

filtrate COP increases glomerular filtration rate

What does high glomerular capillary pressure results from

1. Low resistance to blood flow in afferent arterioles

2. Low resistance to blood flow in glomerular capillaries

3. High resistance to blood flow in efferent arterioles: small diameter vessels

Purpose of Tubuloglomerular feedback

detect increased rate of filtrate flow past macula densa cells

Result of Norepinephrine stimulation

•Constricts small arteries and afferent arterioles

•Decreases renal blood flow and filtrate formation

•During shock or intense exercise: intense sympathetic stimulation, rate of filtrate formation drops to a few ml

Diffusion is the

net movement of molecules from high concentration to low concentration

Facilitated diffusion is the

passive transport of molecules across a membrane using transmembrane proteins

Active transport is the

movement of molecules from low concentration to high concentration - requires energy

Symport is the

movement of two molecules simultaneously across a membrane

Osmosis is the

net movement of water across a semipermeable membrane from an area of low solute concentration to high solute concentration

What does each cell have

1. Apical Surface

2. Basal Surface

3. Lateral suraface

Apical surface

surface that faces filtrate (apical membrane)

Basal Surface

Basal surface: faces interstitial fluid (basal membrane)

Lateral Surfaces

surfaces between cells

Diffusion can also occur

between cells: from lumen of nephron into interstitial fluid

Descending Thin Segment

Highly permeable to water

Ascending Thin Segment

Impermeable to water

Na+ moves across the wall of the basal membrane by

active transport

K+ and Cl- are transported by ____with Na+ across the apical membrane

symport

Ions pass by ______ ______ across the basal cell membrane of the tubule cells

facilitated diffusion

Filtrate is more concentrated at the end of the descending loop of Henle because

water could passively diffuse out of lumen, leaving behind solutes.

ADH present

low volume of high concentration urine

ADH absent

high volume of low concentration urine

Tubular secretion is

movement of nonfiltered substances from the blood into the filtrate

In the Proximal Convoluted Tubule

Glucose, amino acids and ions are reabsorbed from tubule

In the Descending Limb of Loop of Henle

Water is reabsorbed passively, solutes diffuse into tubule

In the Ascending Limb of Loop of Henle

water remains

In distal convoluted tubules and collecting ducts

-Water movement out regulated by ADH

-If absent, water not reabsorbed and dilute urine produced

-If ADH present, water moves out, concentrated urine produced

Ureters

bring urine from renal pelvis to urinary bladder

Urinary Bladder

-Hollow muscular container

•Lined with transitional epithelium

•Muscular part of wall is detrusor muscle

Trigone

triangular area between the entry of the two ureters and the exit of the urethra

Area expands less than rest of bladder during filling

Renal Failure

•can result from any condition that interferes with normal kidney function

Dialysis

duplicates the function of healthy kidneys

Hemodialysis

•Blood is taken from an artery, passed through the tubes of the dialysis machine, and then returned to a vein

Peritoneal Dialysis

•Dialysis fluid is injected into the peritoneal cavity and later drained

•Waste products diffuse from the blood vessels into the dialysis fluid in the peritoneal cavity

What is the pathway of the Venous Drainage

1. Peritubular capillaries

2. Interlobular Veins

3. Arcuate Veins

4. Interlobar Veins

5. Renal Veins