Digestion and urinary

Digestion

• Groups of organs that work together to digest food so that it can be used by the body (nutrients)

• Food is digested as it passed through the body: needs H2O, carbohydrates, fats, proteins, vitamins, minerals

• Composed of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus

• Substance are secreted by the liver, gallbladder, pancreas and salivary glands to help with digestion

• Two types of digestion:–Mechanical – physical breaking and crushing

of food– Chemical – large molecules are broken down

by enzymes (chemical scissors) into smaller particles that the body can use for growth, maintenance, and repair

• Major nutrients – protein, carbohydrates and fats

• Steps in digestion

• (1) Digestion begins in the mouth where teeth (enamel) used to break down and grind food into small manageable pieces

• Teeth are composed of molars, premolars, incisors and canines adults have 32 teeth

• Saliva – (amylase - enzyme) liquid produced by the salivary glands in the gums to begin breaking down complex carbohydrates into simple sugars and moisten food

• (2) pharynx – throat, food is pushed by the tongue to the back of the mouth and enters the pharynx which splits into 2 tubes

• (3)Esophagus – passageway to the stomach

• Squeezes food along the tube with muscle contractions called peristalsis forcing food into the stomach

• (4) stomach – muscular baglike organ connected to the end of the esophagus

• Continues physical digestion by churning food with muscle contractions

• Continues chemical digestion by releasing enzymes and acids (HCl)

• Resulting mixture is called chyme• (5) small intestine – (three parts

duodenum, Jejunum, ileum) chyme is released by pyloric valve into the small intestine slowly allowing the small intestine time to mix chyme with fluids from the liver and pancreas

• Small intestine is approx. 2.5 cm in diameter and about 6 m long (the length of a car) and flattened out would be larger than a tennis court

• Inside wall is covered with villi – fingerlike projections covered with nutrient absorbing cells that allows nutrients to be diffused into the bloodstream by capillaries

• Pancreas is located between the stomach and sm intestine that makes enzymes to help in food digestion and produces an acid neutralizer called bicarbonate– Also part of the endocrine system that makes

hormones that regulate blood sugar (insulin)

• Liver – large as a football located on the right side of abdomen, most massive internal organ

• Weighing up to 1.5 kg and has many jobs:

• Makes green liquid called bile which is used to digest fat molecules

• Stores nutrients

• Breaks down toxic substances in the blood

• Makes cholesterol for cell membranes– HDL – high density phospholipids (good)– LDL – low density phospholipids (bad)

• Gallbladder – stores bile made by the liver and is squeezed into the sm intestine to break up large fat droplets, allowing for easier digestion

• (6) large intestine – stores, compacts, and expels material that are indigestible

• About 7.5 cm in diameter and about 1.5 m long

• No nutrient absorption takes place in the large intestine

• Water absorption takes place and creates a solid mass called feces

• Fiber found in fruits, grains, and vegetables called cellulose is not digestible by humans and is used by the body to keep feces soft and moving in the lg. intestine

• Lg intestine also secretes mucus to allow feces to move smoothly

• Last part of the lg intestine is the rectum where feces is stored before passing out of the body through the anus

• Complete digestion from start (mouth) to finish (anus) takes approx. 24 hrs.

Excretory

• Removes waste products from blood/balances fluids

• Excretion – process of removing wastes and excess products (fluids and some solid matter; filtrates) from the body

• 3 systems remove waste– Urinary, respiratory, integumentary

• Urinary sys. removes waste like CO2 and ammonia from the body

• Blood moves through the kidney’s 350 X’s per day

• Each kidney is composed of over 1 million tiny filters called nephrons

• Each nephron is surrounded by capillaries called the glomerulus encased in a hollow cup-shaped structure called Bowman’s capsule (permeable)

• Materials diffuse across: water, urea, glucose, salts, amino acids and some vitamins (filtrate)

• Plasma, cells, and platelets are to large to pass and remain in blood.

• Removes toxic substances containing nitrogen called urea, which forms as the cells use protein for energy, maintains pH, and blood volume by regulating water

• Ureter – passageway from kidney’s to the bladder

• Urinary bladder – storage area for urine• Urethra – tube where urine leaves the

body• Urine – liquid waste (yellow) that remains

behind when nephrons remove water and other substances and returns these to the bloodstream

• Urination – process of expelling urine

• ADH – antidiuretic hormone produced when your body lacks water

• Signals the kidney’s to take back water from the nephrons and return the water back to the bloodstream

• The process makes less urine but a higher concentration of urine

• Diuretics – thirst is an indication the body needs water

• Diuretics cause the kidneys to make more urine decreasing the amount of water in blood

• caffeine