EXCRETIONNot of feces!!!

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

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

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)

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.

Dermis Functions:

Cool the body Send sensory information about pressure

and heat

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

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

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

Nerves Sense pressure and hot or cold Well you’ll just have to wait until the

next unit to find out how that works

Urinary System1.

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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

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

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

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

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

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