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 Glands Esophagus Stomach Liver Gall Bladder Lg. Intestine Pancreas Sm. Intestine
Villus Small Intestine Circular folds Epithelial cells Villi 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 Excretory System Kidney Ureter Urinary bladder Urethra
Reabsorption As 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. Filtration Most 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. Secretion Substances such as hydrogen ions are transferred from the blood to the filtrate.
Communications In the Body • Two systems involved: • Nervous – • Endocrine –