General Introduction

Excretory Organs

Lungs

Liver

Skin

Kidneys

Functions of the Urinary System

A. Conserves Valuable NutrientsB. Separates/Eliminates WastesC. Regulates Blood Volume and Blood PressureD. Regulates Ion Levels In PlasmaE. Regulates Blood pH

Organs of the Urinary System

• Kidneys

• Ureters

• Urinary bladder

• Urethra

Kidneys: Location

Retroperitoneal

Kidneys: StructureRenal capsule

Several layers of fat

Kidneys: Structure

2 layers:

Cortex

Medulla

Kidneys: Structure

Calyx

Renal Pelvis

Renal Hilus

Nephron

• Glomerulus

• Bowman’s capsule

• Proximal convoluted tubule

• Loop of Henle

• Distal convoluted tubule

Glomerulus and Bowman’s Capsule

Bowman’s Capsule

Podocytes

Pedicels

Filtration Slits

Collecting Duct

Summary of Flow of FluidGlomerular capsuleProximal convoluted tubuleLoop of HenleDistal convoluted tubuleCollecting ductRenal papillaCalyxRenal pelvisUreterBladderUrethraOut of body

Kidneys: Function

Filter wastes and produce urine by:

• Filtration• Reabsorption• Secretion

Ureters: Structure•Mucosa: epithelium

•Muscularis: two layers

•Adventitia: connective tissue

a = lumenb= mucosac = circular muscle layerd = longitudinal muscle layere = adventitia

Ureters: Structure

Ureters: Function

Carry urine from the kidneys to the urinary bladder

Urinary Bladder: Structure

Mucosa (rugae)

Muscularis (Detrusor muscle)

Adventitia

Urinary Bladder: Function

Stores and expels urine

Urethra: Structure

Mucosa

Muscularis

Adventitia

Urethra: Function

Transports urine from bladder to outside body

Female Urethra

Male UrethraProstatic Membranous Spongy/Penile

Blood Flow Through the Kidney (A RAGE PRV I)

•Abdominal Aorta

•Renal Artery

•Afferent Arterioles

•Glomerular

Capillaries

•Efferent Arterioles

•Peritubular

Capillaries

•Vasa Recta

•Renal Vein

•Inferior Vena Cava

Tubular Section of Nephron

Figure 23.4b

Regulation of Water and Electrolytes

The body gains water through 2 processes

1. Absorption

2. Metabolism

Water Loss

• Urinary System

• Lungs

• Skin

• Intestines

Cardiac Output and Renal Function

Cardiac Output =

Stroke volume (ml) Heart Rate (beats/min)

Hormones that Regulate Electrolyte Balance

• Antidiuretic Hormone (ADH or vasopressin)

• Renal-Angiotensin Aldosterone

• Erythropoetin

• Atrial Natriuretic Hormone

Antidiuretic Hormone (ADH)

Released in response to increase in concentration of electrolytes in blood or a fall in blood volume or pressure

ADH decreases the amount of water lost at the kidneys, which reduces the concentration of electrolytes.

ADH also constricts peripheral blood vessels, which helps to increase blood pressure.

Renin-Angiotensin-Aldosterone

• The enzyme renin is released by kidney in response to a decrease in blood volume, blood pressure or both.

• Renin starts chain of reactions that lead to formation of hormone in liver called angiotensin II.

• AG II stimulates adrenal cortex to make aldosterone and posterior pituitary gland to make ADH.

• Both inhibit salt and water loss at kidneys resulting in increased blood volume and blood pressure.

Erthyropoietin

• Released by kidneys in response to low O2 levels

• Stimulates production of RBCs in bone marrow.

• Increase number of RBCs elevates blood volume.

Atrial Natriuretic Hormone

• Cells in right atrium make this hormone in response to increased blood volume.

• Stimulates loss of sodium ions and water at the kidneys

• Inhibits renin release

• Inhibits secretion of ADH and aldosterone

• Result is reduced blood volume and blood pressure.