What is nitrogenous waste and where does it come from?

a.ecretes enzyme “amylase” – starts carbohydrate digestion.

b. Mucous – lubricates food

What is the function of the excretory system?

Removes toxic nitrogenous waste from the body.

In animals, this involves the kidneys and urinary bladder.

What is nitrogenous waste and where does it come from?

1.Contains nitrogen.

2.Comes from proteins broken down during metabolism.

What is nitrogenous waste and where does it come from?

3. Three main types:

a. Ammonia – initial form of all nitrogenous waste and highly toxic. May be excreted as smelly waste or converted to less toxic forms. Ammonia = NH3

What is nitrogenous waste and where does it come from?

3. Three main types:

b. Urea and uric acid – Less toxic forms. Involves less water loss (important for land animals).

Uric acid crystals

Why must these wastes be removed?

1. Nitrogenous wastes are poisonous to the body.

2. Will affect brain, heart, bone joints first.

3. Gout – build-up of uric acid crystals; very painful.

In what forms are these wastes removed?

1. Aquatic organisms – live in water and excrete ammonia; toxic, but water dilutes it.

In what forms are these wastes removed?

2. Terrestrial organisms – live in land; no water to dilute ammonia.

a. Earthworms – can excrete some ammonia through skin into moist soil.

In what forms are these wastes removed?

b. Insects, reptiles, birds – produce uric acid crystals; very little water loss.

c. Humans/mammals – have kidneys to produce urea; some water loss.

Where are the kidneys and what do they do?

1. Location – above hips on either side of spine.

2. Make urine – urea + salts + water

Avg person makes 1 – 2 liters/dayor just over 1 mL each minute!

Functions of kidney and related parts

Liver – combines ammonia with CO2to form less toxic urea

Renal Artery – carries blood into kidney

Functions of kidney and related parts

Nephron – small section of kidney that filters blood (1 million per kidney)

Bowman’s Capsule – filters out urea, water, salts, to become urine

Functions of kidney and related parts

Glomerulus – small branches of renal artery inside Bowman’s capsule.

Tubule – reabsorbs 99% of water taken out by Bowman’s capsule

Antidiuretic Hormone (ADH) – hormone that tells kidney to reabsorb water

Functions of kidney and related parts

Renal Vein – brings blood from kidney back to heart

Functions of kidney and related parts

Ureters – tube that carries urine from kidney to bladder

Bladder – stores urine

Urethra – tube that carries urine from bladder to outside the body.

Problems with the kidney

a.Alcohol – diuretic (increases water in urine)

b. Caffeine - diuretic

Urethra – tube that carries urine from bladder to outside the body.