3.2 Organs and Systems

Learning Goals Learn about medical imaging technology Learn about the different human organ systems Learn about the digestive system

Medical imaging technology are techniques used to form an image of a body’s internal cells, tissues, and organs There are various technologies that can be used for a variety of diagnosis. Some technologies may have a negative impact, thus doctors want to make sure that they use the appropriate technology for the appropriate circumstance. Medical Imaging Technology

X-Ray: is produced by transmitting a wavelength of electromagnetic radiation through the body to expose photographic film on the other side. X-rays tend to be used for bone fractures.

CT or CAT Scan: (computerized axial tomography) take X-rays of thin slices of a body part which can be later reconstructed by a computer.

Ultrasound: high frequency sound waves are directed at part of the body, which shows movement inside the body

MRI Scan: (magnetic resonance imaging) produces high radio signals to create an image of a body part.

Endoscopy: a tiny camera and a light attached to a flexible tube are inserted into the body.

Human Organ Systems

The digestive system is responsible for chemically and mechanically breaking down food. Digestive System Mechanical Digestion: physically breaking down food into smaller pieces Chemical Digestion: the use of proteins (enzymes) to breakdown food

Digestive System There are 4 main stages in the process of digestion: 1) Ingestion 2) Digestion 3) Absorption 4) Excretion

Digestive System There are 4 main stages in the process of digestion: 1) Ingestion 2) Digestion 3) Absorption 4) Excretion

Stage 1: Ingestion - Mouth The process of ingestion occurs in the mouth. The teeth, tongue and salivary glands play a vital role in the ingestion and breakdown of food. Chemical digestion: enzymes (amylase) found in saliva break down the bonds in carbohydrates Mechanical digestion: Teeth breakdown the food into small pieces

Epiglottis: flap covers trachea so food doesn’t get in. It causes the food to only enter the esophagus. Stage 1: Ingestion - Esophagus The walls of the esophagus are stretched by food and a series of rhythmic contractions occur (peristalsis) to help move food down into the stomach.

Stage 2: Digestion - Stomach The stomach walls are folded and can expand after a meal. Glands on the stomach wall release gastric juice – HCl, salts, enzymes, water and mucus The stomach also contracts and relaxes to churn the food. The wall is also covered in a mucus coat – Protects from the acid released from the gastric juices

The small intestine is made up of three main parts: 1) Duodenum 2) Jejunum 3) Ileum Stage 2: Digestion – Small Intestines Further breaks down proteins, fats and carbohydrates

Stage 3: Absorption – Small Intestines Jejunum and Ileum: Contains more folds (villi) than the duodenum, which enables more absorption to occur. Breaks down remaining proteins and carbohydrates to be absorbed Absorbs nutrients and pushes undigested material into the large intestine

Stage 3: Absorption – Large Intestines The large intestine (colon) reabsorbs fluids and electrolytes. It absorbs 90% of water back into the blood. The feces is known as any undigested material that remains. It is stored in the large intestine for elimination through the rectum.

Stage 4: Elimination - Rectum Main component of feces: Cellulose: makes up plant cell walls, cannot be digested by humans Living and dead bacteria Water Toxic wastes are removed People who don’t eat enough cellulose (plant material and fibre) have fewer bowel movements and are at risk of colon cancer

Read Section 3.2 Questions: pg. 99 # Complete Digestive System Handout Homework