Processing the food we eat

• Why do we need food? –Reactants for cell respiration (energy)–Building blocks for new cells, tissues, etc. –Essential nutrients: minerals, vitamins, etc.

• What happens to materials we can’t use? –Stored for later–Excreted–Converted into something we can use

Two main systems involved:

• Digestive: Breaks down food into small molecules (monomers!) and absorb the nutrients into the blood stream for delivery

Two main systems involved: • Excretory: Maintain Homeostasis– internal balance of chemicals–Rids body of metabolic wastes•Wastes produced by body’s metabolism•Eg: Salts, Carbon Dioxide, Urea

• BUT how do we deliver the “good stuff”?

Salivary GlandsEsophagus

Liver

Gall Bladder

Stomach

PancreasSm. Intestine

Lg. Intestine

Swallow

ing

Peristalsis –

Small Intestine Villus

Circular folds

Villi

Epithelial cells

Capillaries

Lacteal

Vein

Artery

Excretion

Major Excretory Organs–Skin – water and salts–Lungs – CO2–Large intestines –

excess/indigestible solid waste–Kidneys and associated organs -

Urea

Renal Vein RenalArtery

Ureter

Urinary bladderUrethra

Excretory System

Kidney

FiltrationMost filtration occurs in the glomerulus. Blood pressure forces water,

salt, glucose, amino acids, and urea into Bowman’s

capsule. Proteins and blood cells are too large to cross the membrane;

they remain in the blood. The fluid that enters the

renal tubules is called the filtrate.

ReabsorptionAs the filtrate flows through the renal

tubule, most of the water and nutrients are

reabsorbed into the blood. The concentrated

fluid that remains is called urine.

SecretionSubstances such as hydrogen ions are

transferred from the blood to the filtrate.

Communications In the Body

Two systems involved: 1.Nervous –

2.Endocrine –