S

Adam, Amy, Karl, Karlene, and Yifan

Excretory System

Introduction

http://www.youtube.com/watch?v=guOqyi5lUQQ (1:46-4:36)

Regulates bodily fluids, excreting and recycling waste Main organs: kidneys, ureters, bladder and urethra Disorders of the excretory system

Excretion

After metabolic activities (energy release, maintenance, repair) results in waste

Separating the needed and the unneeded or no longer needed

Skin, respiratory system, digestive system, excretory system

Major functions

of excretory system

Excretion of waste

Maintenance of

water and salt

pH control

Secretion of

hormones

Overall Major Functions

Functions: Excretion of Metabolic Waste

The average person urinates 3000 a year

Bladder can hold 16-24 ounces of urine

Nitrogenous waste Urea makes up the majority of

this waste

Functions: Maintenance of Water-Salt Balance

Maintain balance with water and salt in blood Regulating blood pressure Balance between potassium, bicarbonate and

calcium Cells need to stay in an isotonic solution

Functions: Maintenance of Acid-Base Balance

Buffer for blood Blood pH: 7.4 Urine is usually a pH of 6 Maintenance of alkaline reserve

Functions: Secretion of Hormones

Aids endocrine system in hormonal secretion

Calcitriol: Promotes calcium absorption

Erythropoiten: Production of red blood cells

Renin

Major Organs

Kidney (Nephron

s)

Ureter

Urinary

bladder Urethr

a

Organs

Kidneys: Lower back, filters waste from blood, functions named above

Ureter: Muscular tubes that carry urine Urinary Bladder: Urine is stored Urethra: Tube that urine is secreted from

Kidney: Introduction

Kidney: Pathway

Nephron

Kidney: Pathway

Filter Tubule Duct

Kidney: Filter

Renal artery enters Bowman’s capsule; glomerulus Walls of glomerulus are impermeable to large

molecules pressurized blood aids filtration

Small molecules are permeable The result is known as filtrate

Kidney: Tubule

Bowman’s capsule is connected to a looped tubule Divided into three parts

Proximal convoluted tubule Loop of Henle Distal convoluted tubule

Used by each nephron for reabsorption

Kidney: Tubule

Proximal convoluted tubule Uses ATP for active transport Drives sodium ions, glucose, and other solutes back

into the blood Water follows these substances into the blood by

osmosis

Kidney: Tubule

Loop of Henle

Kidney: Tubule

Loop of Henle Descending limb extends from within the renal

cortex into the renal medulla; extremely salty Permeable to water; water flows back into blood

Ascending limb is impermeable to water and slightly permeable to solutes Na+ diffuses out of the tubule and into nearby blood

vessels

Kidney: Tubule

In the thick-walled section, more Na+ is removed by active transport (uses ATP) Replenishes medulla’s salt Makes the filtrate less concentrated than surrounding

cortex tissue

Kidney: Tubule

1. Medulla is salty

2. Reabsorption of water causes salt concentration to decrease

3. ATP is used to actively reabsorb sodium ions

4. Increases osmolarity for future filtrate

Kidney: Tubule

Loop of Henle

Kidney: Tubule

Distal convoluted tubule Active reabsorption depends on the needs of the

body (sodium ions) Passive reabsorption of negative ions occurs by

electrical attraction (chloride) Potassium ions and hydrogen ions are actively

secreted by the body

Kidney: Duct

Tubule empties into a large pipe-like channel called a collecting duct Lowers back into the medulla; reabsorbs water

The size of the pores depends on signals from the brain

The result can now be called urine Reabsorbed substances are returned to the body

S

The roles of ADH and aldosterone in regulating water

balance

Water Balance: Pituitary Gland

The pituitary gland is a gland at the base of the brain that sends signals to other glands and organs such as the thyroid gland, adrenal glands, ovaries, and testes Directs them to produce certain hormones Produces LD, ADH, FSH, and growth hormones

Water Balance: The Brain

Water Balance: Aldosterone

Aldosterone is a hormone that is produced by the adrenal glands

It works primarily on kidney (renal) cells to help maintain the balance of fluids and electrolytes in our bodies

It mainly works to control reabsorption of sodium and chloride and secretion of potassium and hydrogen

Water Balance: Aldosterone

Pathway: The role of aldosterone in sodium and water balance

is to regulate fluid and electrolyte balance When sodium and plasma volume is decreased, it

triggers the synthesis and secretion of aldosterone When sodium and plasma volume return to normal

levels, aldosterone secretion is reduced

Water Balance: Adrenal Gland

Water Balance: ADH

A hormone produced in the hypothalamus and secreted by the posterior pituitary gland

ADH stimulates reabsorption of water through the distal tubules and collecting ducts of the kidney, resulting in less water being excreted in the urine, thus conserving water

Water Balance: ADH

Pathway: Part of the brain, the hypothalamus, detects that

there is not enough water in the blood. The hypothalamus sends a message to the pituitary gland, which releases ADH. ADH travels from brain to the kidney and causes the kidneys to absorb more water and concentrate the urine. A lack of ADH results in increased urine volume and increased urination, a condition called diabetes insipidis.

Water Balance: ADH

ADH: antidiuretic hormone Pathway:

Part of the brain, the hypothalamus, detects that there is not enough water in the blood

The hypothalamus sends a message to the pituitary gland, which releases ADH

ADH travels from brain to the kidney and causes the kidneys to absorb more water and concentrate the urine

A lack of ADH results in increased urine volume and increased urination, a condition called diabetes insipidis.

Water Balance: Deficit

Water Balance: Surplus

Water Balance: End of Cycle

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Regulation of Blood pH

Maintaining Blood pH in the Excretory System

Blood pH: Introduction

The normal pH of blood is around 7.4 Allows our enzymes to function optimally

Failing to maintain homeostasis causes our blood pH to either increase or decrease This increase/decrease can result in serious medical

condition

Blood pH: Introduction

One way our blood pH can change in based on the foods/liquids we consume Blood pH can also changed from metabolic

processes Three main homeostatic mechanisms used to

maintain blood pH Acid-Base Buffer System Respiratory Centre Kidney Function

Blood pH: Acid-Base Buffer

Buffers blood; prevents changes in pH Takes up extra H+ ions of extra OH- ions that enter

the blood One of the most important buffer system involves

the use of carbonic acid and bicarbonate ions

Blood pH: Acid-Base Buffer

The system reacts differently depending on the presence of extra hydrogen ions of extra hydroxide ions

If H+ is added, the reaction that occurs is: H+ + HCO3

- H2C03

When OH- ions are added to blood: OH- + H2CO3 HCO3

- + H2O

Blood pH: Acid-Base Buffer

In the first reaction, the bicarbonate ion takes up excess hydrogen ion, in order to form carbonic acid

In the second reaction, water is produced Water will help maintain the blood pH, since water is

neutral These reactions temporarily prevent major

changes in pH

Blood pH: Respiratory Centre

The hydrogen ion concentration is raised, the respiratory centre (in the medulla oblongata) increases breathing rate It does this through specific signals that ensure our

breathing muscles contract and relax regularly Doing this causes the body to get rid of hydrogen

ions

H+ + HCO3- H2CO3 H2O + CO2

Blood pH: Respiratory Centre

When the reaction moves from carbon dioxide to hydrogen, the blood pH decreases and increases the other way

Increasing breathing causes carbon dioxide to be generated more quickly, decreasing the number of hydrogen ions

It is vital to have the correct proportion of carbonic acid to bicarbonate ions in blood

Breathing causes a readjustment so the proportion is correct so H+ and OH- can continue to be absorbed

Blood pH: Kidneys

The first two mechanisms are aided by powerful actions of the kidneys Only the kidneys are able to rid the body of a vast

range of acidic and basic substances Kidneys are slower acting, but have a more

powerful effect It is possible to urinate the excess acidic H+ ions or

basic HCO3- ions in order to raise or lower blood pH

Blood pH: Kidneys

Imagine the kidneys as releasing H+ and reabsorbing HCO3

- in order to maintain homeostasis

If blood is too acidic, H+ is released and HCO3- is

absorbed However, if blood is basic, neither is used

Another way of buffering is by using ammonia Removes hydrogen ions and adds in bicarbonate

ions NH3 + H+ NH4

+

Blood pH: Kidneys

Ammonia is produced in the tubule cells through the breakdown of amino acids

Ammonia works to produce ammonium ions For every ammonium ion that is produced, a new

HCO3− is made

Blood pH: Summary

There are three mechanisms used to maintain homeostasis, in terms of blood pH Acid-Base Buffer System Respiratory Centre Kidney Function

Each one has a unique way of doing so All three have advantages and disadvantages that

go along with them

Dialysis: Introduction

What is dialysis? Procedure that removes

wastes and excess fluid from the blood when kidney function is lost due to renal failure

Why is dialysis needed? Hyperkalemia

High potassium Hyperphosphatemia

High phosphate Uremia Edema

Dialysis: Two Types

Conclusion

The human excretory system is responsible for removing liquid waste from the body

The excretory system also regulates the acid-base balance and water-salt balance of the blood and secretes some hormones like ADH

The kidneys are composed of millions of functional units called nephrons that filter the waste from the blood and produce urine.

Dialysis is the procedure that removes wastes and excess fluid from the blood when kidney function is loss due to renal failure

Question #1

What is urine?

Answer

Filtrate of the nephron upon leaving the collecting duct; exits the body through the urethra

Question #2

What is a function in the excretory system that is involved in regulating blood pressure and the

appropriate potassium, bicarbonate, and calcium levels in blood?

Answer

Maintenance of Water-Salt Balance

Question #3

What is the role of ADH?

Answer

Stimulates reabsorption of water through the distal tubules and collecting ducts of the kidney Results in less water being excreted in urine

Question #4

What is the pituitary gland?

Answer

Gland at the base of the brain Send signals to other glands and organs to

produce certain hormones

Question #5

What is this picture showing?

Answer

Respiratory Centre Equation

Question #6

What is this picture showing?

Answer

The process of how the kidneys maintain the pH of blood

Question #7

Name the 2 types of dialysis. What are their differences?

Answer

Hemodialysis Removing wastes and excess fluids from the blood

by an external devices connected to an artery and a vein in a person’s arm.

For acute renal failure Peritoneal Dialysis

Removing wastes and excess fluids from the blood by inserting a catheter into the abdominal cavity.

For Chronic renal Failure

Question #8

What type of dialysis is this picture showing?

Answer

Hemodialysis

References

http://www.nhlbi.nih.gov/health//dci/Diseases/hlw/hlw_controls.html

http://h2g2.com/approved_entry/A8819652 https://www.inkling.com/read/textbook-of-medical-

physiology-guyton-hall-12th/chapter-30/combination-of-excess-h-with

Grade 12 Biology Textbook

Carter-Edwards, T., Gerards, S., Gibbons, K., McCallum, S., Noble, R., Parrington, J.,...Whyte-Smith, A. (2011). Biology 12. Canada, McGraw-Hill Ryerson, pp.444-462.

DeBruyne, L. K., Pinna, K., & Whitney, E. (2012). Nutrition & Diet Therapy (8thed.). United States, Wadsworth, Cengage Learning, pp595-607.

http://www.youtube.com/watch?v=cc8sUv2SuaY http://www.youtube.com/watch?v=WtrYotjYvtU http://www.webmd.com/a-to-z-guides/function-

kidneys http://science.howstuffworks.com/life/human-biolo

gy/kidney1.htm