Biology - Digestive System
Essay by myaat • December 17, 2017 • Study Guide • 1,904 Words (8 Pages) • 1,321 Views
Biology
Digestive System
Breaks down food mechanically and chemically in order to release nutrient molecules that the body's cells can absorb and use. It removes solid waste from the body.
Parts of the digestive systems
Salivary glands
Parotid Glands
Submandibular Glands
Sublingual Glands
Pharynx
The back of the throat
The mouth
The mouth breaks down food mechanically with the teeth and tongue.
Breaks down food chemically with enzymes that are released into the mouth.
Esophagus
Consists of smooth muscle tissue and contracts and relaxes without conscious thought (called peristalsis)
The Stomach
The main functions are to hold food and churn it using smooth muscles
Stomach lining contains cells that produce digestive enzymes (pepsin) and acids (HCL).
The small intestine
Long and narrow
Consists of the duodenum, jejunum, ileum
Most of the digestion occurs
Large Intestine
The large intestines are smaller than a small intestine but are wider, they absorb water from food and the remain are excreted in feces.
Liver
The liver produces the bile and helps the breakdown of fats
Gall bladder
The gallbladder stores and concentrates the bile releasing it into the small intestine
Pancreas
Produces pancreatic fluids that breakdown fat, carbohydrates and proteins
Respiratory System
Organs of a respiratory system are responsible for the body's gas exchange, bringing oxygen in the body and getting rid of carbon dioxide.
The respiratory system and the circulatory system are connected and one cannot function properly without the other.
Parts of the respiratory system
Nasal Cavity
Filters, warms and moistens incoming air
Pharynx
The back of the throat
Epiglottis
Prevents food from entering the trachea
Larynx
Contains the vocal chords
Trachea
Carries air to the bronchus
Bronchus
Carries air to the lungs
Bronchiole
carries air to the alveoli
Diaphragm
The Nose
Air passed by the epithelial cells that have microscopic, hair like projections called cilia
These cells create secrete mucus
The cilia and mucus help keep foreign parties such as dust and bacteria out of your body
The Lungs
Once through the nasal passage and pharynx the air moves into the trachea.
The air passes into branching tubes called the bronchus.
Each bronchus continues to branch sales tubes called bronchiole.
Gas Exchange
Air passes into smaller tubes until it ends up in tiny sacs called alveoli
Alveoli have thin walls and are surrounded by a network of capillaries
O2 and CO2 diffuse across the walls into and out of the bloodstream
The Circulatory System
The circulatory systems transports nutrients and oxygen to cells and to carry wastes to organs.
The Heart
The muscular organ between the lungs
Has four chambers, 2 upper thin-walled atrias and 2 lower thick- walled ventricles.
The septum is a wall dividing the right and left side
Passage of blood through the heart
Superior/ inferior vena cava→ right atrium→right ventricles→pulmonary arteries→lungs→pulmonary veins→left atrium→left ventricle→aorta→to the body.
Blood Vessels
Has 3 blood vessels: arteries, capillaries and veins.
Arteries
Take blood away from the heart
Largest artery is the aorta
Have thick muscular walls
All carry oxygenated blood
Capillaries
Have walls only one cell thick to allow the exchange of gas and nutrients in the tissues and lungs.
Veins
Drain blood from the capillaries
Take blood from the heart
Have thin walls and valves that prevents backward flow of blood
All veins except for pulmonary veins carry deoxygenated blood
Parts of the circulatory system
Superior Vena Cava
Blood vessels bring deoxygenated blood from the upper body back to the heart.
Inferior Vena Cava
Blood vessels bring deoxygenated blood from the lower body back to the heart.
Right
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