Excretion

Excretion (definition)

The removal of metabolic waste from the body

Organs of excretion in animals

lungs, kidneys, skin

What do the lungs excrete?

carbon dioxide, water

What does the skin excrete?

Sweat

What is sweat made of?

Water, salts

What do the kidneys excrete?

Urine (water salts and urea)

Draw and label a diagram of the skin

...

What are the organs of excretion in plants?

Leaves (stomata), stems (lenticels)

What do the leaves excrete?

Oxygen, water vapour, carbon dioxide

What do the lenticels excrete?

Carbon dioxide

Functions of skin

Protection, temperature regulation, excretion, production of vitamin D

How does our skin protect us?

Epidermis acts as a barrier to prevent water loss and entry of pathogens

What is the normal human body temperature?

37 degrees Celsius

How is heat transported around the body?

in blood plasma

Draw the urinary system

...

Which artery carries blood to the kidney?

Renal artery

Which vein carries blood away from the kidney?

Renal vein

What carries urine to the bladder?

Ureter

What controls the opening and closing of the bladder?

Sphincter muscle

What stores urine?

Bladder

How does urine leave the bladder?

Urethra

Where are the kidneys located?

Below the diaphragm in the back of the abdominal cavity

What are the millions of structures in kidneys called?

Nephrons

Functions of the Nephron

filtration, reabsorption, secretion, osmoregulation

Where in the nephron does filtration occur?

Bowman's capsule (cortex)

Where in the nephron does reabsorption occur?

proximal convoluted tubule (cortex), loop of Henlé (medulla), distal convoluted tubule (cortex)

Where in the nephron does secretion occur?

Distal convoluted tubule (cortex)

Where in the nephron does osmoregulation occur?

Collecting duct (medulla)

Osmoregulation (definition)

The control of the balance between water and salt in the body

Where is the cortex of the kidney located?

outer region

Where is the medulla of the kidney located?

middle region

Where is the renal pelvis of the kidney located?

inner region

How many nephrons does a kidney have?

1-2 million

Adaptations of the nephron

Pressure in glomerulus is high due to efferent arteriole being narrower than afferent arteriole. Surface area of glomerulus capillaries is large. Walls are porous. Bowman's capsule one cell thick

Where does unfiltered blood enter the glomerulus enter from?

Afferent artiole

Where does filtration occur?

Glomerulus

What is forced out of the plasma into Bowman's capsule? What does it form?

glucose, amino acids, vitamins, water. Glomerular filtrate

What is too big to enter the glomerular filtrate?

Large proteins, white blood cells, red blood cells.

What is reabsorbed in the PCT?

food molecules, most water, most salts

How are food molecules and salts reabsorbed in the PCT?

diffusion, active transport

How is water reabsorbed in the PCT?

osmosis

What is reabsorbed in the Loop of Henle?

some water, some salts

What is reabsorbed in the DCT?

some water, some salts

What does the blood secrete?

Potassium and hydrogen ions

Why does thee blood secrete ions into the DCT

Maintain blood pH

What part of the nephron can become more/less permeable depending on ADH?

collecting duct

What controls the volume of urine?

Controlled by ADH

What part of the brain releases ADH?

pituitary gland

How does ADH reach the kidneys?

Travels by the bloodstream

What does ADH do?

Collecting duct becomes more permeable to water, allowing more water to be reabsorbed

What happens when salt concentration in the blood plasma is too high?

ADH released

What happens when salt concentration in the blood plasma is too low or normal?

ADH not released

Affect on volume of urine when ADH is released

Decreases (more concentrated)

Affect on volume of urine when ADH is not released

Increase (more dilute)

Kidney failure treatments

dialysis, kidney transplant

Draw a nephron

…