Chapter 18: Digestive and Excretory System Essential Question: How is our food broken down so our cells can use it?

I. Digestive system A.Digestion: process of breaking down food into molecules the body can use B. Gastrointestinal tract: location where digestion occurs

Mouth Salivary glands Stomach Pancreas (behind stomach) Large intestine Small intestine Rectum Gallbladder (behind liver) Liver Esophagus Pharynx The Digestive System Section 38-2 Interactive slide

1.Mouth: teeth tear and chew food into small particles a) Mechanical digestion: chewing DigestionDigestion b) Chemical digestion: involves a change in the chemical nature of the nutrients ChemicalChemical c) Salivary glands produce saliva: mixture of water, mucus, and amylase (enzyme) d) Saliva softens and lubricates food and breaks down some starch

2. Esophagus: muscular tube that connects pharynx with the stomach a) Bolus: chewed up food that is swallowed into the pharynx and then into the esophagus b) Epiglottis closes over the trachea c) Peristalsis: series of rhythmic muscular contractions that move bolus through the esophagus

3. Stomach: sac like organ involved in mechanical and chemical digestion a) Three layers of smooth muscles turn and twist the stomach to help churn the contents of the stomach (mechanical digestion) b) Inner lining of the stomach is a thick, wrinkled mucus membrane c) Gastric pits: small openings in lining that release secretions into the stomach d) Acidic digestive fluid: mucus, enzymes, and hydrochloric acid StomachStomach

C. Chemical Digestion 1. Gastric fluid: carries out chemical digestion in the stomach a) Pepsin: enzyme that breaks down proteins b) Hydrochloric acid: lowers the pH for pepsin to work and kills bacteria and dissolves minerals c) Mucus: forms protective coating for the stomach against the hydrochloric acid d) Ulcer: sore in stomach because mucus lining breaks down, caused by a bacteria

2. Formation of chyme: food and gastric fluid mixture a) Cardiac sphincter: circular muscle between esophagus and stomach b) Pyloric sphincter: circular muscle between the stomach and small intestine that regulates the flow of chyme

3. Liver: large organ located to the right of stomach a) Many different functions b) Secretes bile c) Bile: breaks down fat into smaller pieces d) Gallbladder: stores bile and releases it into the small intestine

4. Pancreas: organ that lies behind the stomach a) Secretes digestive enzymes into the small intestines b) Contains sodium bicarbonate that changes the acidic chyme into a base so enzymes can work

Liver Gallbladder Duodenum Bile duct Pancreas Pancreatic duct To small intestine The Liver and the Pancreas Section 38-2

5.Small intestine: coiled tube 21 feet long that finishes digestion and absorbs nutrients into the blood a) Duodenum: first section that finishes chemical digestion of chyme b) Jejunum: middle section c) Ileum: last section

Small Intestine Villus Circular folds Villi Epithelial cells Capillaries Lacteal Vein Artery The Small Intestine Section 38-2

6. Absorption: end products ( amino acids, monosaccharides, glycerol, and fatty acids) of digestion are transferred into blood and lymph a) Villi: fingerlike projections on the folded lining of the small intestine b) Villi produce a large surface, where nutrients are absorbed by diffusion and active transport into the blood and lymph Absorption

D. Large intestine or colon 1. Minerals, vitamins, and water are absorbed from the undigested material 2. Four parts: ascending, transverse, descending, and sigmoid 3. Reflex contractions move the remaining material out of the body through the anus Digestive System Chart PreziDigestive System Chart Prezi (Interactive slide)

II. Urinary System A.Excretion: process of removing metabolic wastes and helps to maintain homeostasis by regulating the content of water and other substances in the blood B. Kidneys 1. Remove nitrogen wastes made by the breakdown of proteins 2. Two bean-shaped organs located in the back behind the stomach and liver

3. Structure a) Cortex: outermost portion b) Medulla: inner portion c) Renal pelvis: funnel-shaped structure in the center d) Renal artery: transports nutrients and wastes into the kidneys e) Renal vein: carries blood out of kidneys

Kidney (Cross Section) Cortex Medulla Vein Artery Kidney Ureter Urinary bladder Urethra The Urinary System Section 38-3

f) Urea: metabolic waste that is made in the liver from ammonia and enters bloodstream to the kidneys 4. Nephrons: functional units of kidneys that remove wastes

Kidney Nephron Cortex Medulla Renal artery Renal vein Ureter To the bladder Bowman’s capsule Glomerulus Capillaries Collecting duct To the ureter Loop of Henle Artery Vein Structure of the Kidneys Section 38-3

a) Urine: produced in nephrons and contains toxins, urea, water, and salts b) Each kidney has over a million nephrons c) Bowman’s capsule: cup-shaped structure that holds glomerulus

d) Glomerulus: group of capillaries that receives blood from renal artery e) High pressure forces fluids from the blood through the capillary walls and into Bowman’s capsule f) Renal tubule: long tube that collects fluids filtered from the blood

g) Three parts of the tubule: proximal convoluted tubule, loop of Henle, and distal convoluted tubule h) Materials are exchanged between tubule and blood by three major processes

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. 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. Secretion Substances such as hydrogen ions are transferred from the blood to the filtrate. The Nephron Section 38-3

5. Filtration: materials from blood are forced out into Bowman’s capsule a) Forces filtrate out of blood (water, urea, glucose, vitamins and salts) b) Large molecules like proteins and blood cells remain in the blood

6. Reabsorption: many of the needed substance are transported across the walls of the tubule back to the blood a) Occurs in proximal convoluted tubule b) Water moves by osmosis c) Glucose and minerals are moved back by active transport

7. Secretion: substances pass from blood into filtrate in the distal convoluted tubule a) Wastes and toxic materials b) Hydrogen ions to adjust pH of blood 8. Formation of urine: remaining fluid and wastes in the distal convoluted tubule form urine a) Flows into a collecting duct where more water moves out b) 99% of water is returned to the blood by the end of the process ProcessProcess

9. Loop of Henle: helps the collecting duct return water to blood by osmosis a) High concentration of sodium chloride is created by the loop of Henle so water will move out of collecting duct Nephrons Kidney

Nephron Cortex Medulla Renal artery Renal vein Ureter To the bladder Bowman’s capsule Glomerulus Capillaries Collecting duct To the ureter Loop of Henle Artery Vein Structure of the Kidneys Section 38-3

C. Elimination of urine 1. Urine from collecting ducts enters the renal pelvis 2. Ureter: narrow tube that leads from each kidney to bladder 3. Urinary bladder: muscular sac that stores urine 4. Urethra: tube from bladder that leads out of the body

Kidney (Cross Section) Cortex Medulla Vein Artery Kidney Ureter Urinary bladder Urethra The Urinary System Section 38-3

5. Body must remove 500 ml of urine each day to remove toxic materials from body 6. Adult removes 1.5 L to 2.3 L a day

III. Excretory system A.Kidneys are the primary organs of the excretory system 1. Life –threatening situation if kidneys fail 2. Can survive using one kidney

Vein Artery Shunt Air detector Dialysis machine Blood pump Blood in tubing flows through dialysis fluid Used dialysis fluid Compressed air Fresh dialysis fluid Kidney Dialysis Section 38-3

Dialysis

B. Lungs 1. Eliminate carbon dioxide 2. Carry out detoxification: altering harmful substances so that they are not poisonous C. Skin: secretes sweat to remove excess water and salt 1. Person working in extreme heat can excrete 1L of water per hour by sweating g of salt per day Types of excretion

Calculation How much blood does the glomerulus (kidneys) filter per day? 125 mL of blood is filtered per min

Answer 125 ml/min x 60 min x 24 hr = 180,000 mL /day 1 hr 1 day 180,000 mL x 1 L = 180 L / day 1000 mL 180L is 47.5 gallons