The Digestive System Purpose of the Digestive System

The Digestive System

Purpose of the Digestive System • Turning food into microscopic nutrients that can be absorbed through the intestinal lining • What is the toughest food that the human body might try to break down? ▫ Fibre – made from plants (vegetables and grains)

How does food get broken down? • Mechanically ▫ Mouth chews food to break it into smaller pieces ▫ Stomach churns • Chemically ▫ Liver produces bile to mix water and fat together for digestion ▫ Gastric acid is produced by the cells of the stomach lining (it would burn your hand!)

Structure of the Digestive Tract • http: //medtropolis. com/virtual-body/

The Importance of the Sphincter • Without a sphincter, the digestive track is really just a hole through your body • Sphincter – a ring of muscle that holds a biological opening closed • Over 50 different sphincters in the human body

Two Types of Sphincter’s • Voluntary - Controllable ▫ Rectum – both voluntary and involuntary sphincter’s ▫ Sphincter Urethrae - Urinary sphincter

2 Types of Sphincter’s • Involuntary - Not in your control ▫ Ileocecal valve – closes off the small intestine so that food that has not fully broken down may not pass ▫ Sphincter pylori – Holds food in the stomach until it is thoroughly mixed with stomach acid

Olestra • Fat substitute used in the 1980’s • zero calories, zero grams of cholesterol and zero grams of fat • gastrointestinal symptoms — including diarrhea, loose stools, nausea, gas • Olestra sometimes causes underwear staining • “greasy, hard-to-wipe-off fecal matter” • anal leakage (leakage of liquid olestra through the anal sphincter).

My Roomate • He did not have an esophogeal sphincter • Always got heart burn (acid moving up from your stomach into your esophagus) • Had a muscle from his leg fashioned into a sphincter to prevent it

Demo • Digestion of Fat -

What’s wrong with me Doc? • Day 1: ▫ Pain in stomach area • Answers: ▫ Lot’s of fibre, good amount of veggies, not too much red meat ▫ 2 days of on and off pain ▫ Bowel movements – 1 -2/day (regular)

What’s wrong with me Doc? • Day 2: Pain moves down and to the right side ▫ Excrutiating pain when I walk ▫ Some nausea and vomiting • Answers: • I know I have collitis. Do I have collitis? How could I test for it?

The Circulatory System

Purpose of the Circulatory System • Transports nutrients and oxygen to cells • Transports waste and carbon dioxide away from cells

Getting Around the Body • The heart pumps blood through the body • It pumps blood to the lungs to exchange gases and comes back to the heart • The heart then pumps blood around the rest of the body to transport gases to the cells

• Capillaries – Act as an exchange point for gases and nutrients • These happen in the: ▫ Lungs ▫ Intestines ▫ Every single cell in the body

Structure of the Circulatory System • Video

Respiratory System

Purpose of the Respiratory System • To provide all cells in the human body with Oxygen and remove Carbon Dioxide produced as waste by each cell

Fact • You breathe 15 times per minutes and move 10, 000 L of air in and out of your lungs each day • With every breath, you breath in at least one particle of air that Gandhi breathed in when he was alive

Respiratory System Structure

Gas Exchange

Carbon Monoxide Poisoning • When we breathe in Carbon monoxide, it takes the place of oxygen on the red blood cells • Since RBC’s cannot carry oxygen, the tissues in the human body start to malfunction • The brain relies on oxygen and is one of the first organs affected • You will feel nausea, head aches, loss of consciousness and more

Breathing • You breath without having to ask your body to do so • If you hold your breath too long, when you fall unconcious, your body will start to breathe again

Musculoskeletal System

Purpose • The musculoskeletal system supports the body, protects delicate organs and makes movement possible

• Muscles üBundles of long cells. üContract and expand when signalled by nerve cells. üSkeletal muscle attached to bone by tendons

Muscles üMuscles contract – get shorter and thicker.

Muscles üVoluntary üInvoluntary

Osteoporosis

Nervous System

Purpose of the Nervous System • To sense the environment and coordinate an appropriate response

Nervous System ▪ The nervous system is made up of the brain, spinal cord, and peripheral nerves. ▪ It senses the environment and coordinates an appropriate response. ▪ The core of the nervous system is the brain and the spinal cord. This is called the central nervous system.

� Nerves are bundles of special cells called neurons, surrounded by connective tissue. � Neurons are communication specialists that send information around the body using electrical signals. � There approximately 100 billion neurons in the human brain.

Neuron Facts Human brain has over 100 billion neurons If lined up, they’d make a line over 600 miles long Neurons do not undergo mitosis Signals can be sent as high as 180 miles/hour

The peripheral nervous system consists of the nerves that carry the signals between the central nervous system and the body.

Human Body is an Electrical Circuit • Let-go Voltage

Reflexes �Reflexes are actions that do not require the involvement of the brain: they occur without conscious thought. �The spinal cord acts as a short cut for reflexes.

Functional MRI (Magnetic Resonance Imaging) • Detects electrical activity in the brain

Congenital Analgesia • Congenital Insensitivity to Pain • Malfunction of path of pain signals to the brain or the brain’s failure to interpret them • Very dangerous for children because they can hurt themselves without knowing it. • We feel pain so we don’t injure ourselves