1. Excretion
Not of feces!!!

2. Main Organs Involved in Excretion
Lungs – remove carbon dioxide from the body through respiration
Skin – removes urea, salt, and excess water through sweat
Kidneys – remove urine (urea, salt, and excess water) through filtration and urination

3. Skin The skin has two layers
Dermis – lower layer of skin that is made up of cells, sweat glands, sebaceous glands, blood vessels and nerves
Epidermis – upper layer of skin covered in dead skin cells and live replicating cells below those

4. Epidermis Functions: Prevent Water Loss
Prevent absorption of unwanted materials
Protect cells contained by the skin
Keep dividing to keep up with the number of cells lost via friction (your skin touching other things)

5. Epidermis Epidermis has four layers
Stratum corneum – top most layer composed of dead skin cells that protect the cells below it
Stratum granulosum – this layer of cells is about to die and become the next layer. The cells are full of granules that will keratinize to offer our skin the protection it needs
Stratum spinosum – This layer is full of lipids that reduce water loss from the skin
Stratum basale – the cells in
this layer are constantly
dividing to provide the above
layers with new cells.

6. Dermis Functions: Cool the body
Send sensory information about pressure and heat

7. Sweat Glands
Sweat glands are located all over the skin except on lips and nipples.
They are essentially a ball of tubing which straightens and extend to the surface of the skin creating a pore
The purpose of the sweat gland it to
cool the body when it is too hot
Some sweat glands excrete an odor
as well as sweat. These are mostly
concentrated in the arm pits and
genital region

8. Capillaries
The capillaries in the dermis supply the sweat gland with the fluid and wastes to make sweat
The provide oxygen and nutrients to the dividing cells in the basal layer of skin cells and to the nerves and hair follicles in the dermis

9. Hair Follicles
A sac of cells that creates hair and which the sebaceous (oil) gland is connected
The base that is enriched with capillaries is the only living part of the hair
Hair is important because it is
attached to nerves which send
sensory information about how
the hair moves
It also helps prevent air from
stealing our warmth

10. Nerves Sense pressure and hot or cold
Well you’ll just have to wait until the next unit to find out how that works

11. Urinary System 1. 5. 4. 3. 2. 6. 7.

12. Kidneys A large artery called the renal artery
flows into the kidney and divides into
tiny capillaries
The capillaries join nephrons which
makes up the kidneys where wastes
such as urea and salt are filtered out
Then the newly filtered blood leaves through the renal vain to travel back to the heart
The waste materials flow into the ureter
The inner portion of the kidney is the medula and the outer layer is the cortex

13. Nephron
The capillaries form a ball called the glomerulus which is surrounded by the Bowman’s capsule
The Bowman’s Capsule thins out and forms a loop (Loop of Henle)
The capillaries go around the loop and as the loop descends the concentration changes pulling more urea out of the blood via diffusion

14. Ureter
The wastes (salt and urea) pulled from the blood by the Loop of Henle travel to the collecting duct, which leads to the Ureter
The ureter is the tube that urine (composed of urea, salt, and water) travels down from the kidneys to the bladder

15. Urinary Bladder
The bladder is a large muscular sac that holds the urine until there is enough to pass out of the body
The bladder is flexible and expands with increasing urine and contracts to push the urine out of the body through the urethra

16. Urethra
This is the tube that connects the bladder to the outside of the body
In men it has a smaller diameter and is much longer than in women

17. Excretory Diseases
Kidney stones – build up of minerals inside the kidneys until those minerals form a stone
Urinary Tract Infections – bacterial infection of the urethra and bladder causing irritation and bleeding
Kidney Disease – when the nephrons in the kidney start to die and stop filtering the blood (dialysis)
Gout – a build up of uric acid in the blood
Boils – a bacterial infection of the sweat gland causing it to swell and become very uncomfortable