Biology Introduction to Human Anatomy & Physiology Chapter 35
Digestion The breakdown of complex biological molecules into their component parts. Lipids to fatty acids Proteins to individual amino acids Carbohydrates into simple sugars
Mechanical Digestion Changes the physical form of food Chew Tear Grind Mash Mix
Chemical Digestion Changes the chemical composition of food with the aid of digestive enzymes
Phases of Digestion Ingestion Movement Digestion Absorption
The Digestive Tract Parts of the Digestive Tract Mouth Pharynx Esophagus Stomach Small Intestine Large Intestine
Accessory Parts Organs that are not in the digestive tract but helps in the digestion Liver Gall bladder Pancreas
Anatomy of the Mouth and Throat
Peristalsis
Stomach Pepsin major enzyme; converts proteins into peptides in the presence of HCL. Mucus lubricates food and protects the gastric lining from strong digestive juices.
Stomach
Small Intestine Has folded inner walls covered with fingerlike projections (villi; sing. villus)
Small Intestine Site of greatest amount of digestion and absorption
Large Intestine a.k.a. Colon larger diameter, but shorter (5 ft) Water is absorbed from the undigested food making the waste harder until it becomes solid.
Large Intestine
Accessory Organs Liver Produces bile (watery, greenish substance) Secretes bile to the gall bladder
Accessory Organs Gall bladder Secretes bile to the duodenum through the bile duct during mealtime. Bile is an emulsifier, NOT an enzyme. Emulsifier dissolves fat into the watery contents of the intestine.
Pancreas Accessory Organs Produces a juice that contains enzymes (amylase) Secretes the juice into the duodenum through the pancreatic duct.
35.2 Nutrition Read this section! Know macromolecules: Carbohydrates Fats Proteins Know vocab words: Mineral (inorganic) Vitamin (organic; fat-soluble or water-soluble) Calorie
Endocrine System
Digestive and Endocrine Systems Action of Hormones Endocrine glands produce hormones, which are released into the bloodstream and distributed to body cells. Hormones are classified as steroid hormones and amino acid hormones.
Steroid Hormones Soluble in lipids and therefore can diffuse through plasma membrane Bind to a receptor in the cell The hormone and receptor bind to DNA in the nucleus, which stimulates protein synthesis.
Amino Acid Hormones Nonsteroid hormones are composed of amino acids. Bind to receptors found on the plasma membrane of a target cell because they cannot diffuse through the plasma membrane
Negative Feedback What is negative feedback? Negative feedback returns a system to a set point
Endocrine Glands and Their Hormones Pituitary gland Situated at the base of the brain (not part of brain) Secretes hormones that regulate many body functions Regulates other endocrine glands
Link to the Nervous System The hypothalamus produces two hormones: oxytocin and antidiuretic hormone. The antidiuretic hormone (ADH) functions in homeostasis by regulating water balance.
Comprehension Check
Thyroid and Parathyroid Glands Thyroxine increases cellular metabolism. Calcitonin helps regulation of calcium. Parathyroid hormone increases blood calcium levels.
Pancreas Secretes the hormones insulin and glucagon which work together to maintain homeostasis
Adrenal Glands Located just above the kidneys Manufactures the steroid hormone aldosterone and a group of hormones called glucocorticoids Plays an important role in the flight or fight response by secreting epinephrine and norepinephrine