Digestive System

• Human Digestive System has two key functions:– Breaking down of

large food into smaller, usable molecules

– Absorbing these smaller molecules

Digestive System

• The digestive system includes the– Mouth– Pharynx– Esophagus– Stomach– small intestine– Liver– Gallbladder– Pancreas– large intestine– Rectum

Mouth

• Mechanical Digestion– Tongue and teeth work

together to break down food mechanically

– Type of teeth reflect dietary habits

• Chemical Digestion– Amylase - enzyme in

saliva that breaks the carbohydrates

• chemical bonds between the sugar monomers in starches

Esophagus, Pharynx, Epiglottis

• Esophagus– No digestion– Food is directed from mouth, to pharynx, to

esophagus.• Epiglottis – flap of cartilage

– Ensures food travels to esophagus and not wind pipe (larynx)

Stomach

• Stomach - large muscular sac that continues the mechanical and chemical digestion of food

– Acidic pH – 2-3 on the pH scale– Cardiac sphincter – circular muscle that keeps materials down in

the stomach. Stops acid and food from reentering the esophagus

– Mechanical Digestion - • Peristalsis

– Chemical Digestion – protein digestion begins here• HCL and Pepsin - The combination of pepsin (enzyme) and

hydrochloric acid begins the complex process of protein digestion. Pepsin breaks proteins into smaller polypeptide fragments.

– HCL changes inactive enzyme, pepsinogen active pepsin• Rennin – enzyme that aids in the digestion of the protein in milk• Chyme - mixture of stomach fluids and food produced in the stomach

by contracting stomach muscles

Ulcers – tissue erosion

• Can occur in stomach, esophagus, or the duodenum (upper intestine.)– Bacteria

Heliobacter pylori can lead to ulcers, but can be treated with antibiotics

Small Intestine

• Digestion is completed and nutrients are absorbed here.– pH – 8 and length of 6m– Digestion completed in Duodenum first 10 inches.– Digestion

• Intestinal Enzymes– Pancreatic amylases – starch– Peptidases (trypsin, chymotrypsin) – proteins amino acids– Nucleases – nucleic acids nucleotides– Lipases – break down fat

– Absorption – villi (villus-singular) – millions of fingerlike projections (latter portion of small intestine)

• Increase surface area• Capillaries – absorb amino acids, vitamins, monosaccharides• Lacteal – absorbs fatty acid and glycerol lymphatic system• Each villus contain microvilli

Villi and the Small Intestive

Liver

• Liver - large organ just above the stomach that produces bile, a fluid loaded with lipids and salts– Accessory gland– Produces bile that emulsifies fat– Bile mixed with Sodium Bicarbonate

pH 11 (pancreas), neutralizes “chyme” coming from the stomach

– Sends bile to gallbladder for storage– Other functions

• Breaks down/recycles red blood cells• Detoxifies blood – removes alcohol &

drugs• Produces cholesterol for cell

membranes• Produces Urea (nitrogenous waste)

from protein metabolism

Gallbladder and Pancreas

• Accessory glands

• Gallbladder– Stores bile– Cholesterol

Deposits (gallstones)

• We can function without it

• Pancreas– Secretes

peptidases – protein digestive enzymes

To Small Intestine

• Liver, Pancreas, and Gall Bladder• Accessory structures, including the liver

and pancreas, add secretions to the digestive system. The pancreas secretes enzymes that help break down carbohydrates, proteins, and fats.

• Pancreas - gland that produces hormones that regulate blood sugar; enzymes that break down carbohydrates, proteins, lipids, and nucleic acids; and sodium bicarbonate, a base that neutralizes stomach acid

• Liver - large organ just above the stomach that produces bile, a fluid loaded with lipids and salts

• Gallbladder – Stores Bile

Small Intestine

• Villi - folded projection that increases the surface area of the walls of the small intestine

Large Intestine or Colon

• large intestine – No digestion– 3 major functions

• Egestion – removal of undigested waste

– Rectum – last 7-8inches stores feces for release

• Vitamin Production– B, K, folic acid

• Reabsorption– Constipation– Diarrhea

Hormones that Regulate the Digestive System

Hormone Site of Production

Effect

Gastrin Stomach wall Stimulate secretion of gastric Juice

Secretin Duodenum Wall

Stim. Pancreas to release bicarbonate

Cholecystokinin Duodenum Wall

Stim. Pancreas to release enzymes and gallbladder to release bile

The Appendix

• Some animals have appendixes in which cellulose is digested by bacteria. In humans, the appendix appears to do little to promote digestion.

The Circulatory System

Circulatory System

• The human circulatory system consists of the heart, a series of blood vessels, and the blood that flows through them.

The Heart – about the size of your cliched fist• Pericardium – protective sac the heart is

enclosed in • Myocardium - thick middle muscle layer of the

heart; pumps blood through the circulatory system• Atrium - upper chamber of the heart that receives

and holds blood that is about to enter the ventricle• Ventricle - thick-walled, muscular, lower chamber

of the heart that pumps blood out of the heart• Pulmonary Circulation - pathway in which the

right side of the heart pumps blood to the lungs• Systemic Circulation - pathway in which the left

side of the heart pumps blood to all of the body except the lungs

• Valves - flap of connective tissue between an atrium and a ventricle, or in a vein, that prevents backflow of blood

Circulation of Blood Through the Heart1. Vena Cava2. Right Atrium3. Right

atrioventricular (AV) tricuspid valve

4. Right Ventricle5. Pulmonary

Semilunar Valve

6. Pulmonary Artery

7. Lungs8. Pulmonary

veins9. Left Atrium10.Left

Atrioventricular (AV) bicuspid valve

11.Left Ventricle12.Aortic

Semilunar Valve

13.Aorta14.To all the cells

of the body

Circulation

• 4 chambered Heart

• 3 loop system circulatory system

Heartbeat

• Pacemaker - small group of cardiac muscle cells in the right atrium that “set the pace” for the heart as a whole; also known as the sinoatrial node

Circulation System

• Aorta - large blood vessel in mammals through which blood travels from the left ventricle to all parts of the body except the lungs

• Artery - large blood vessel that carries blood from the heart to the tissues of the body. – High Pressure, can contract and expand

• Capillary - smallest blood vessel; brings nutrients and oxygen to the tissues and absorbs carbon dioxide and waste products– Thin so nutrients can be passed to cells

or waste material absorbed• Vein - a blood vessel that returns blood to

the heart. – Low pressure, no muscles in walls

Circulatory System

• One-way Valves• Exercise

Blood Pressure

• Systolic – first number, measures the pressure on the arteries when the ventricles are contracted

• Diastolic – second number, measures the pressure on the arteries when the ventricles are relaxed

• Normal blood pressure 120/80

Questions

1. List the structures of the circulatory system.

2. Compare the functions of the three types of blood vessels in the circulatory system.

3. Describe the path of blood circulation through the body.

4. How is heartbeat controlled? 5. Explain how regular exercise can

promote good circulation.

Blood

Blood CompositionComponent Scientific Name Properties

Red Blood Cells Erythrocytes •Carry hemoglobin and oxygen.•No nucleus•Avg. Life 120days•Formed in bone marrow•Recycled by Liver

White Blood Cells

Leukocytes •Fight infection•Formed in Bone marrow•Die fighting infection (pus)

Plasma None •Liquid portion of blood. (90%) water•Contains:•Clotting factors•Hormones•Antibodies•Dissolved gasses•Nutrients & wastes

Platelets Thrombocytes •Clot blood•Formed in bone marrow by megakaryocytes

Blood Composition

Red Blood Cells

• Red blood cells transport oxygen.

• Mature RBC have no nuclei.

• Last for about 120Days

White Blood Cells

• Produce in Red Bone Marrow• No Hemoglobin; Contains Nucleus

White Blood Cells

Clotting

• Thromboplastin, prothrobin, thrombin, fibrinogen, and fibrin are all clotting proteins found in blood plasma

• Mechanism– Thromboplastin & Ca+ ions

are released by damages cells & stimulates the

– Conversion of prothrombin thrombin & stimulates

– Conversion of Fibrinogen Fibrin (clot)

Respiratory System

Respiratory System

• The respiratory system consists of the: nose– Pharynx - muscular tube at the end of the

gastrovascular cavity, or throat, that connects the mouth with the rest of the digestive tract and serves as a passageway for air and food

– Larynx - structure in the throat containing the vocal cords

– Trachea - windpipe; tube through which air moves

– Bronchi - passageway leading from the trachea to a lung

– Lungs: bronchiole and alveoli– Alveolus - tiny air sac at the end of a

bronchiole in the lungs that provides surface area for gas exchange to occur

Gas Exchange (Alveoli)