1. Multicellular Organisms
Excretory System
Multicellular Organisms

2. Water Regulation and Excretion
The kidneys receive blood through the renal artery, at a very high pressure
This artery’s high Pressure is maintained as you proceed into the Kidney and the artery splits off into smaller capillaries
Bonus question: Why is it important for this blood to be at high pressure?

3. Water Regulation and Excretion
Each of these capillaries then carries the blood to tiny cup-shaped structures called Bowman’s capsules.
The Bowman’s capsule is the starting point of a structure known as the Nephron.
Each Kidney is composed of millions of Nephrons and they have the specific function of filtering blood.

4. Nephrons Water Regulation and Excretion
Diagrams from PowerPoint: Human Body and Kidney
Explanation of beginning and end points, scaffold with thought-provoking questions
Walk through the different parts of a Nephron
Nephrons
Water Regulation and Excretion

5. Water Regulation and Excretion
Nephron

6. Water Regulation and Excretion
Overall, the process involving the nephron is broken up into three parts:
Filtration
- High renal artery blood pressure forces the glomerular filtrate through the capillary walls into the bowman’s capsule
- This filtrate is composed of waste substances that need to be excreted, but also other substances that are still useful to body function
2. Reabsorption
- This process occurs in the section between the Bowman’s Capsule and the Collecting Duct.
- Useful substances, such as glucose and ions, are extracted by the walls of the nephron and passed into the surrounding capillaries
Secretion
- Some substances, such as urea, are actively removed from the tubal wall and pushed into the filtrate.
- This waste, in the form of urine, leaves the nephron through the collecting duct into the ureter and heads off to bladder

7. Water Regulation and Excretion
Water Regulation & Excretion – Activities:
1. Read Page 177 – 179.
2. Copy the diagram of the nephron from page 178.
3. Do Questions 10 & 11 on page 179

8. Water Regulation and Excretion
Molecule
Area 1 (%)
Area 2 (%)
Area 3 (%)
Glucose 17 26 25
Na+ 7 33
Protein 35
Urea 76 41 15
Using the data shown above, state and describe which parts of the
Nephron align to the Areas shown.

9. Dialysis Water Regulation and Excretion
Water regulation and Excretion are Homeostatic processes, meaning that they help to maintain normal levels of water, salt and wastes in the human body.
When the Kidney loses its function, for example due to Diabetes or High Heart Pressure, its ability to ‘filter’ the blood and maintain these levels is lost.
Therefore, patients like this require special machinery to assist them. The dialyzer mimics the filtration step by having a series of partially permeable membrane tubes which assist in the regulation or removal of urea and ions.

10. Multicellular Organisms
Circulatory System
Multicellular Organisms

11. Nutrient Circulation and Exchange
In animals, transport and exchange of important materials such as gases and nutrients is facilitated by the circulatory system.
This is important, as cells require a constant supply of nutrients to drive metabolic processes
The circulatory system is involved in a number of interactions with every organ of the body.
Question: From your memory, name some of the components of the circulatory system

12. Exchange Surfaces
Exchange of nutrients occurs at specific surfaces of the body, which all possess the same three characteristics
Thin
Moist
Large Surface Area
Why are these important?
Human cells are also surrounded by fluid that assists the cell in the exchange process. In particular this fluid is important for the supply of nutrients and removal of wastes

13. Nutrient Circulation and Exchange
The Circulatory system in animals is composed of:
The Heart, the ‘pump’ which provides the force for fluid movement
Blood, the fluid that allows for the transport of dissolved nutrients and wastes
Blood Vessels, the tunnel-like structures through which the blood travels to body tissues
Discussion: How should we define veins and arteries?

14. The heart Nutrient Circulation and Exchange
The heart is composed of cardiac muscle arranged to give four chambers. These chambers are known as the Atria and Ventricles. Pumping of blood through these four chambers gives rise to the familiar ‘heartbeat’ sound.
The right side of the heart receives deoxygenated blood from the body through the superior and inferior Vena Cava. The blood is then pumped to the lungs via the pulmonary artery.
The blood exchanges carbon dioxide for oxygen, then returns to the left side of the heart via the pulmonary veins.
From here, the now oxygenated blood is pumped to the rest of the body for exchange.
Question: Pulmonary Artery/Vein?

15. Blood Blood is a fluid containing both cells and cellular fragments.
The fluid components of blood contains: plasma, dissolved gases, hormones and nutrients
The cellular component includes: Red Blood Cells, White Blood Cells and Platelets
These cells have a variety of different roles- Nutrient transport (RBC), Immune Defense (WBC) and repair (platelets)

16. Blood vessels Nutrient Circulation and Exchange
After leaving the heart, blood travels in specialized transport structures called Blood Vessels. Blood Vessels have different characteristics depending on their position in the body- and as such come in three different types:
Arteries: Transports blood away from the heart. Thicker elastic wall linings
Veins: Transports blood back to the heart. Thinner wall linings alongside valves
Capillaries: narrow tubular structures responsible for the nutrient exchange at tissues

17. Lymphatic vessels Nutrient Circulation and Exchange
Alongside Blood Vessels there are Lymphatic Vessels:
Lymph Vessels surround tissue cells and are connected to Blood Vessels
They collect the excess fluid between cells that has filtered from the capillaries
Usually this filtrate contains blood cells and proteins, but can also contain dead cells and microorganisms
The lymph capillaries drain into larger lymph vessels which can return the liquids back to the circulatory system to maintain blood volume

18. Nutrient Circulation and Exchange
Activities:
Read pages , 160
Answer questions 7-9 (pg 160)
With the person next to you, discuss some lifestyle choices that would affect cardiovascular function