UNIT 4: EXCRETION AND WASTE

MANAGEMENTIntroduction

List as many waste products of the human body as possible.

What are waste products?

◦What would happen

if you never threw

out your garbage or

leftover food?

What are waste products?

◦Why do

we sweat?

What are waste products?

◦Why do we urinate?

Excretion and Homeostasis

◦Homeostasis is the process that makes sure

everything in the body is kept stable.

◦Excretion helps this process by

getting rid of the wastes your

body produces.

What is excretion?

◦Excretion: removal of metabolic waste from the

body to maintain homeostasis.

◦Metabolism: all of the chemical reactions that

occur in the cells of an organism.

◦(ex: cellular respiration, photosynthesis, digestion)

Let’s imagine…

◦We ate a big mac for lunch.

◦What kind of waste products do you think we will

produce?

◦Bun = carbohydrates

◦Meat = proteins

◦Vegetables = carbohydrates

◦Others = fat and sodium (salt)

In our cells◦ These materials get broken down even further

Waste Product Origin of Waste Product Excretory Organ

Ammonia NH3 Breakdown of amino acids (from

proteins) in the liver

Kidneys

Urea CO(NH2)2 Conversion of ammonia in the liver Kidneys, skin

Carbon Dioxide Cellular respiration (breakdown of

glucose in cells)

Lungs, intestines, skin

Water Cellular respiration (breakdown of

glucose in cells

Kidneys, lungs, intestines,

skin

Mineral Salts

(NaCl)

Food and water Kidneys, skin

◦Ammonia, one of the products of cellular

metabolism, is very toxic. This is why it is converted

to urea (much less toxic) in the liver before being

released into the bloodstream.

◦ Too much ammonia in your body can cause psychological

problems like confusion, tiredness, and possibly coma or death.

Ammonia Urea

Ammonia NH3

2 NH3 + CO2 → CH4N2O + H2OAmmonia carbon dioxide urea water

Organs involved in waste management

◦Liver *not included in excretory

system but plays important roles

◦Lungs

◦Skin

◦Intestines

◦Kidneys

Liver◦ Largest internal organ in the body

1.Formation of urea

◦Converts toxic ammonia into urea which is then excreted in our urine (yellow)

2.Detoxification

◦Removes toxins, such as alcohol, drugs, and bacteria from the blood

Liver3. Production of bile

◦Emulsification of fats (easier for absorption)

4. Storage of extra sugar

◦ in the form of glycogen. The liver changes glycogen into glucose and secretes it back into the bloodstream when the body needs energy.

Bile

◦ Bile contains bile salts, cholesterol, part of hemoglobin molecules from old

red blood cells.

◦ Bile is released by the gall bladder to digest fats in the small intestine.

◦ Most bile salts are reabsorbed

in the large intestine and

returned to the liver to be

reused.

◦ The remainder are passed in

feces.

◦ Too much bile salts can cause diarrhea

What happens when wastes are not excreted properly and reabsorbed into the blood?

Liver Cirrhosis

◦The liver is overgrown with extra tissue which cuts

down blood flow and lowers its ability to purify blood.

◦Can lead to death.

◦Caused by overloading the

liver with harmful materials,

like alcohol.

Jaundice◦ Too much bilirubin in the blood.

◦ Bilirubin is produced by the normal breakdown of red blood cells.

Normally, it passes through the liver, which releases it into the

intestines as bile

Why is excrement (feces) not included in the list of metabolic wastes?

◦Excrement is not a product of cellular

metabolism.

◦It is a “leftover” after the body absorbs what

nutrients it needs from the small intestine

Lungs

◦When you inhale and exhale

◦Your lungs exchange CO2 and

O2

◦ Toxic CO2 is eliminated while O2 is

taken in

◦Also exhale water vapour

Skin

◦ Thermoregulation

◦ Evaporation of sweat lowers

body temperature

◦Contains sweat glands that

excrete perspiration

through skin pores.

◦Perspiration is made up of

nitrogenous wastes (urea),

salts, and water.

Large Intestines

◦Eliminate solid wastes

that remain after the

digestion of food.

Kidneys◦Act as filters

◦ remove urea and excess water

and salts from the blood.

◦ the waste becomes urine and is

then moved from the kidneys to

the bladder

◦More on this later

u

renal arteries

renal veins

Review Questions

◦What is metabolism?

◦What is metabolic waste?

◦What waste products do humans

excrete?

◦What organs are involved?

UNIT 4: EXCRETION AND WASTE

MANAGEMENTThe Urinary System

Questions

What is urine?

How is it formed?

Liquid Wastes from Digestion

◦Waste that leaves the kidneys is called urine.

◦Urine is composed of mostly water, salts, and urea.

◦Urine leaves the kidneys, travels

down the ureters and is stored in

the bladder.

◦Leaves the body through

the urethra.

The Bladder

◦Can hold a maximum of about 400-600 mL of fluid.

◦When there’s about 250 mL of urine in the bladder, we

become aware of it.

◦500 mL, we become very

uncomfortable.

Urinary Sphincters

◦2 rings of muscles that control the drainage of urine from the bladder. ◦One is involuntarily controlled by the brain.

◦ The other we learn to voluntarilycontrol.

Urethra

◦Urine exits the body through the urethra.

◦Males – urethra is ~ 20 cm long◦Merges with the vas deferens from the testes to form a single urogenital tract.

◦Females – urethra is ~4 cm long◦Reproductive and urinary tracts have separate openings.

Urinary Tract Infection (UTI)

◦Bacteria enters the urethra

◦More in common in females due to short urethra

Kidneys

◦ Humans have 2 fist-sized kidneys, found in the lower back on either

side of the spine.

◦ Function: to filter the blood in order to remove metabolic waste

products from the body.

◦ Urea, uric acid, creatinine

◦ Filters 180 litres of blood, produces 1 litre of urine

Kidneys

◦ The human body can function with only 1 kidney.

◦ The functioning kidney increases in size to handle the increased workload.

Other Functions of the Kidney

◦ Control water balance in the blood (affects blood pressure)

◦ Control pH levels of the blood

◦ Control levels of sodium, potassium, bicarbonate, and calcium ions

in the blood

◦ Secrete hormones that stimulate

red blood cell production and

activate vitamin D production in

the skin.

Kidney Structure

◦Renal cortex is the outer layer

(filtration)

◦Renal medulla consists of

pyramid shaped masses of

tissue (collects)

◦Renal pelvis is extended into

the ureter (transports urine)

Kidney Structure

◦When you look at the kidney under high

magnification, the kidney is composed of over 1

million nephrons

The Nephron◦ Consists of 5 parts: ◦ Bowman’s capsule

◦ Proximal tubule

◦ Loop of Henle

◦ Distal tubule

◦ Collecting duct

◦ Upper portion of the nephron is found in the renal cortex.

◦ Loop of Henle is located in the renal medulla.

Zac Nephron?

Nephron

The Nephron (cont’d)

◦ Tubules are surrounded by cells and a network of

capillaries.

◦ Any material that isn’t being removed from the body is returned

to the capillaries

Kidney's Filtration Process

◦3 Steps

◦ Filtration (filters

everything out of

blood)

◦ Reabsorption (returns

the good stuff)

◦ Secretion (gets rid of

the bad stuff)

Step 1: Filtration◦ Blood enters the nephron through a tiny artery that branches to form a

network of capillaries called the glomerulus.

◦ Blood pressure forces some blood plasma and small particles (water,

urea, sugar, etc.) out of the glomerulus and into the Bowman’s capsule.

◦ Cup-like sac around the glomerulus that acts as a filter

◦ Larger blood components

(proteins, blood cells),

remain in the capillaries.

Brian Bowman's Capsule?

Filtered Not Filtered (too big)

Nitrogenous wastes

(urea, ammonia)

Proteins

Water, salts, sugars Blood cells, platelets

Minerals, vitamins, some

drugs

Filtration (cont’d)◦ The fluid in the Bowman’s capsule is called the nephric

filtrate. Contains the molecules and ions that have

been filtered out of blood (sugars, salts, etc.)

◦ The nephric filtrate is pushed out of the capsule into the

proximal tubule.

Step 2: Reabsorption

◦When the nephric filtrate enters

the proximal tubule, reabsorption

begins.

◦ Materials required by the body are

returned to the bloodstream.

◦ Osmosis, diffusion, and active

transport draw water, glucose, amino

acids, and ions from the filtrate.

◦ Occurs until the filtrate is isotonic to

the surrounding cells.

Kidney Threshold Level

◦Different for different substances.

◦ If the concentration of a substance in blood is greater

than a certain level, excess is not reabsorbed and

remains in urine for excretion.

◦Ex: high blood sugar

level in a diabetic.

180 litres of blood are filtered daily. Do we urinate 180 litres a day?

◦~179 litres of water are reabsorbed. Only ~1 litre is

excreted

Reabsorbed Not Reabsorbed

Most water Some water

Nutrients Much nitrogenous waste

Required salts Excess salts

Reabsorption (cont’d)◦ Filtrate moves from the proximal tubule to the loop of

Henle.

◦Water is removed by osmosis.

◦NaCl is removed by diffusion.

Step 3: Secretion

◦Get rid of the waste!

◦Renal tubule → collecting duct →

renal pelvis → ureter →urinary

bladder → urethra

◦H2O, salts, urea, uric acid, and

drugs are transported from blood

to tubule

◦ The fluid from a number of nephrons moves from the distal

tubules into a common collecting duct.

◦ In the collecting duct, the fluid is now called urine which moves

into the renal pelvis.

◦At this point:

◦ 99% of the water that entered

the proximal tubule has been

returned to the body in

addition to nutrients like

glucose and amino acids.

Last Stop

◦ From the renal pelvis, urine will enter the ureter and be

stored in the bladder until it is time to be expelled

through the urethra

Kidney Stones◦ Substances can crystallize out of urine in the urinary tract or

kidney.

◦ If too big to be passed, must be surgically removed or

shattered in to small pieces using sound waves or lasers.

◦Diet increases the risk of stone formation.

◦ Low fluid intake, salt, refined sugars,

grapefruit juice, apple juice, cola

drinks, too much animal protein.

Assignment

◦ Create a chain concept map to illustrate:

◦ The main parts of the nephron

◦ The direction of water and solute movement in each part

Assignment◦ Create a chain concept map to illustrate:

◦ The main parts of the nephron

◦ The direction of water and solute movement in each part

GlomerulusProximal convoluted

tubule; loop of Henle,

distal convoluted tubules

Collecting duct

Urine

Blood BloodBlood

UNIT 4: EXCRETION AND WASTE

MANAGEMENTWater and Salt Balance

◦Why do we sometimes

excrete a lot of urine and

sometimes hardly any?

◦Why do we sometimes feel

so thirsty we can hardly get

enough to drink, but

sometimes we don’t want to

drink anything at all?

Osmoregulation

◦The ability of the body to

maintain a constant

internal fluid balance.

Water/Salt Balance

◦ The amount of water and salt in the body needs to remain

constant.

◦ Important for neuron and muscle function

◦ Fluid taken in by the body must, therefore, balance out fluid

excreted by the body.

◦ The kidneys work with two hormones

to maintain the balance of blood

volume and composition through

negative feedback mechanisms.

Hormones

◦ADH (anti-diuretic hormone): promotes more

water absorption back into the bloodstream

(blood volume and blood pressure rises)

◦Anti = no Uretic = urine

◦NO URINE HORMONE

◦Aldosterone: regulates sodium levels in the body.

Water Balance◦ Dehydration: blood volume is

lower than normal.

◦ The hypothalamus in the brain

detects the narrowing of the

blood vessels (vasoconstriction)

and instructs the pituitary gland to

release ADH.

◦ ADH reduces urine volume by

causing the collecting tubules to

allow more water to be

reabsorbed into the bloodstream.

Too much fluid in the body◦Blood volume is higher than normal.

◦ The hypothalamus in the brain detects the widening of the blood vessels (vasodilation) and instructs the pituitary gland to stopreleasing ADH.

◦Excess water passes out of the body as dilute urine.

How does the body regulate blood pressure?

◦Aldosterone increases sodiumre-absorption, which increases water re-absorption into the blood from the collecting tubules. ◦ Amount of water in urine

decreases.

◦ Blood volume and blood pressure increases.

What do you think would happen from eating salty potato chips?

◦ Salt is absorbed into your bloodstream through the wall

of the small intestine.

◦ This leads to dehydration

◦Receptors in the body alert the brain of the saltiness in

the blood – aldosterone is released.

◦ The kidneys will reabsorb more salt and

therefore more water. Blood volume

increases.

Alcohol prevents the release of ADH, what do you think would result from drinking it?

◦ If ADH is inhibited, water would not be re-absorbed in

the nephron.

◦More water would be excreted in urine.

◦ Repeated trips to the bathroom

◦End result is dehydration.

◦Causes hangovers

UNIT 4: EXCRETION AND WASTE

MANAGEMENTKidney Disease

What is kidney disease?

◦A gradual loss of kidney function.

What could cause kidney failure, malfunction, and disease?

Have you signed a donor card?

◦Why would someone sign?

◦Why would someone not sign?

Facts

◦http://www.theorganproject.net/transplantation-

statistics/

What types of organ donations are there?

◦Living

◦Kidneys, parts of the liver, lung/part of the

lung, part of pancreas, part of intestines

◦Bone marrow, umbilical cord blood, blood

◦Deceased

What organs can be donated in Canada?

Does my age, pre-existing medical condition or sexual orientation prevent me from being a donor?

◦Everyone is a potential donor regardless of age, medical condition or sexual orientation. The oldest Canadian organ donor was 92 and the oldest tissue donor was 104. Even individuals with serious illnesses can sometimes be donors. Your decision to register should not be based on whether you think you would be eligible or not. All potential donors are evaluated on an individual, medical, case-by-case basis.

How old do I have to be to register my intent to be an organ donor?

◦If you are under the age of 18 you must

have a parent co-sign your donor card or

register you on signupforlife.ca.

If I have indicated my intent to be an organ and tissue donor, will medical staff still do everything possible to save my life?

◦The first and foremost concern for healthcare

professionals caring for critically ill patients is to

do everything possible to save lives. The

possibility of donation is only considered when all

lifesaving efforts have failed.

What does it mean to consent to donate organs and/or tissue for medical education or scientific research?

◦Every effort is made for the recovered organs and tissue

to be used for transplant. If for any reason this is not

possible and you have consented to scientific research

and/ or medical education, the recovered organs and

tissue may be used for these purposes. Medical

education and scientific research is conducted in

accordance with the policies and procedures of the

establishments involved. These types of donations are

important for enhancing medical staff training and

evolving technology.

Living Donor

◦ https://www.youtube.com/watch?v=HUwWTfUNvsY

What is dialysis?

◦4-hour session

◦3 times a week

Organ Trade

UNIT 4: EXCRETION AND WASTE

MANAGEMENTUrinalysis

Why do we give urine samples

when we visit the doctor for a

physical examination?

What kinds of things can

doctors detect with a urine

test?

Why do athletes get their urine

tested?

Before you get alarmed…

◦Did you eat beets, berries, or rhubarb?

◦Did you eat asparagus?

Urinalysis

◦A test of your urine’s physical and chemical properties

◦ Indicator of overall health

◦Used to detect a wide range of disorders:◦ UTIs

◦ Kidney disease

◦ Diabetes

◦ Involves checking the appearance, concentration, and content of the urine. Abnormal results may point to a disease or illness.

What else can they detect?

Pregnancy!

Research

◦How do home pregnancy tests work?

A urinalysis has 3 parts◦1. Visual examination

◦ Affected by concentration, diet, and hormones

◦ Colour, clearness

◦ Yellow – orange (dehydration)

◦ Red/pink = Blood (bladder/kidney infections, stones, kidney

disease, cancer)

◦ Cloudy = Pus (infection)

◦ Bubbles = Protein (kidney disease)

Scent

◦ Sweet = high amount of ketone bodies (When fats are

broken down for energy, chemicals called ketones

appear in the blood and urine.)

◦ Seen in diabetics

◦ Starvation or low carb diet

A urinalysis has 3 parts

◦2. Dipstick examination

◦ Chemically treated strip. Checks

for:

◦ Protein (kidney disease)

◦ Glucose (diabetes)

◦ Ketones (diabetes)

◦ legal and illegal drugs,

◦ pH (UTI, kidney stones, other)

◦ Bacteria and white blood cells (UTI)

◦ Hormones (pregnancy)

A urinalysis has 3 parts

◦3. Microscopic examination

◦ Red blood cells – kidney disease, kidney stones, infections,

bladder cancer, or blood disorder

◦ White blood cells – infection

◦ Bacteria/Yeast – infection

◦ Crystals – clumps of minerals, may form kidney stones

Lance Armstrong

Diego Maradona

Maria Sharapova

Alex Rodriguez

Barry Bonds

Marion Jones

Performance Enhancing Drugs

◦ Urine is tested for drugs, steroids, and hormones in their system

◦ Steroids

◦ Body produces large amounts of testosterone

◦ Promotes muscle growth

◦ Enhances male traits

◦ Human Growth Hormones (HGH)

◦ Increases muscle mass and burns fat

◦ Promotes healing

◦ Natural hormone produced by the body to

increase height

Should urinalysis be mandatory for all pro athletes?Write a well thought out response and hand in to Ms. Maslanka

Why can’t we drink saltwater?