HUMAN EXCRETORY SYSTEM

EXCRETION The removal of cellular wastes (Metabolic Waste) from the body.

Major Metabolic Wastes Carbon Dioxide (CO2) Produced as a result of cellular respiration. Water (H2O) An end product of many chemical reactions including cell respiration and dehydration synthesis. Nitrogen Wastes An end product of the breakdown of protein. Ammonia – most toxic Urea – mildly toxic Salts Produced as a result of chemical reaction

Main Organs of Excretion

Organs of Excretion: Lungs  Removes carbon dioxide and water Liver  Urea is formed which resulted from break down of amino acids and breakdown of RBCs Skin  Sweat Glands -Removes excess water and salts, urea and heat. Kidneys  Remove water, salts and urea

Liver Removal and detoxification of harmful substances from the blood (bacteria, drugs, hormones, alcohol)

Liver Removal of broken down RBC’s

Liver Deamination Ammonia (NH3) is formed by the breakdown of amino acids

Liver ammonia is converted into a less toxic substance, urea, which enters the bloodstream to the kidneys for excretion

The Skin

The Skin Sweat comes out of pores in your skin. Mixture of three metabolic wastes: Water Salts Urea

The Skin As you sweat, your body accomplishes two things: 1) It has a cooling effect on the body. 2) metabolic wastes are excreted  

The Lungs

The Lungs Cellular respiration produces carbon dioxide as a waste product. 

The Kidneys The major excretory organ in the human body Filtering of the blood helps regulate its chemical composition.  Water soluble materials are absorbed from blood by diffusion in the kidney. Needed materials are reabsorbed Wastes: Urea, salts and excess water are excreted

Organs of the Urinary System

Organs of the Urinary System Kidneys Two kidneys are located on either side of the spinal column near lower back. Ureter Two tubes that leaves each kidney carrying urine to the urinary bladder. Urinary Bladder Muscular sac that stores liquid wastes before excretion. Urethra Carries the urine from the bladder to the outside of the body – controlled by a sphincter muscle.

The Functions of the Kidney 1. Filtration of blood: water, urea, amino acids, salts, glucose pass out of the blood into the Kidneys by diffusion Proteins (enzymes, hormones, antibodies) and blood cells remain behind in the blood

The Functions of the Kidney 2. Reabsorption: Important substances are returned to the blood (water, glucose, amino acids, salts) by active transport and diffusion

The Functions of the Kidney 3. Formation of urine: (urea, excess water, salts)

The Kidneys There are three major areas in the kidney Outer portion is the cortex Middle portion is the medulla Inner portion is the renal pelvis

The Kidneys Bean-shaped about 10 cm long each. Nephron: The functional unit of the kidney Renal artery and Renal vein leading to and from the kidneys

Parts of the Nephron Glomerulus Bowman’s Capsule Ball of capillaries surrounded by the Bowman’s Capsule. Bowman’s Capsule Cup-shaped structure that filters the materials out of the blood.

Parts of the Nephron

Filtration of the Blood Filtration occurs as blood pressure forces fluid from the blood in the glomerulus into the lumen of Bowman’s capsule Filtration of small molecules is nonselective RBC’s and Protein don’t get filtered The filtrate contains salts, glucose, and nitrogen wastes

Pathway of the Filtrate From Bowman’s capsule, the filtrate passes through three regions of the nephron: the proximal tubule, the loop of Henle, and the distal tubule Fluid from several nephrons flows into a collecting duct, all of which lead to the renal pelvis, which is drained by the ureter

From Blood Filtrate to Urine: A Closer Look Proximal Tubule Reabsorption of Salts , Glucose . Nutrients Takes place by Active and Passive Trasport

Distal Tubule Regulates the K+ and NaCl concentrations of body fluids Helps in pH regulation

Collecting Duct The collecting duct carries filtrate through the medulla to the renal pelvis This is where the filtrate becomes more concentrated.

Flow through Kidney: Renal Artery Glomerulus Bowman’s Capsule Loop of Henle Collecting Tubule( Duct ) Ureter Bladder Urethra

Malfunctions of the Urinary System

Malfunctions of the Excretory System Urinary Tract Infection (UTI)- Bacterial infection that can affect any part of the urinary system. Nephritis: Bacterial infection of the kidney.

Malfunctions of the Excretory System Kidney Stones – Caused by accumulation of a crystallized solid such as calcium Treatment: Sound waves Surgery

Gout: Disease associated with abnormal uric acid production and excretion - causing deposits in the joints (toes) resulting in severe pain.

Gout:

Kidney (Renal) Failure Prolonged Blockage Prolonged infection- Untreated Polycystic Kidney Disease Diabetes High Blood Pressure Illegal Drug Use Prescription Drugs Treatment: Dialysis Kidney Transplant

Review Questions… 1. Which is the correct pathway for the elimination of urine? a) urethra, ureter, bladder, kidney b) kidneys, urethra, bladder, ureter c) bladder, ureters, kidney, urethra d) kidneys, ureters, bladder, urethra

Review Questions… 2. In humans, for carbon dioxide to be excreted, it must pass from the blood into: a) nephrons b) alveoli c) sweat glands d) the liver

Review Questions… 3. A blockage in a ureter would interfere with: a) urine entering the kidney b) urine entering the bladder c) urine leaving the body d) urea entering the kidney

Review Questions… 4. Which is NOT a metabolic waste in humans? a) carbon dioxide b) oxygen c) salt d) urea e) water

Review Questions… 5. In which form are nitrogenous wastes excreted in humans? a) ammonia b) uric acid c) urea d) amino acids

Review Questions… 6. Nitrogenous wastes are the result of metabolism involving: a) lipids b) carboohydrates c) inorganic compounds d) proteins

Review Questions… 7. In addition to water, the principal components of urine are: a) amino acids & fatty acids b) urea & salts c) ammonia & bile d) hydrochloric acid & urea

Review Questions… 8. Name a malfunction of the excretory system and explain how it can upset the homeostasis of an organism.