Human Body Systems: Digestion, Respiration, Circulation
The Digestive System
The digestive system is responsible for transforming food into simpler substances that can be used by the cells. It is made up of the digestive tract and digestive glands.
Digestive functions:
- Ingestion
- Digestion
- Absorption
- Egestion
Chewing is a mechanical action by which food is shredded. Insalivation is the process of wrapping food in saliva.
The Respiratory System
The respiratory system is responsible for taking oxygen from the air outside, taking it to the blood, and removing carbon dioxide. The exchange of gases between the internal and external environment occurs in the pulmonary alveoli.
Ventilation
Lung ventilation is the process by which atmospheric air enters the interior of the lungs and then leaves these to the atmosphere.
The diaphragm is a muscle that lies below the lungs. Because of its movements, it varies the capacity of the ribcage. The intercostal muscles are the ribs that connect with each other.
The Internal Environment
The internal environment is the set of fluids surrounding the cells of an organism. Plasma is a liquid with interstitial, defensive, and nutritional functions. Blood is a means of transport of substances that runs through the inside of blood vessels. Lymph is a fluid that is formed from interstitial plasma.
Homeostasis
Homeostasis is the maintenance of the properties of the cells. The circulatory system distributes nutrients and oxygen throughout the body while collecting waste products of cell metabolism.
- The arteries carry blood from the heart to the body.
- The veins carry blood from the organs to the heart.
- The capillaries connect the ends of the arteries with the beginnings of the veins.
Functions of blood:
- Nutrition
- Respiration
- Excretion
- Defense
- Temperature regulation
Blood is made up of:
- Plasma: a yellowish liquid that contains a variety of substances.
- Blood cells: there are three types: red blood cells, white cells, and platelets.
Heart
The mitral valve connects the left atrium and ventricle. The tricuspid valve connects the right atrium and ventricle.
The Functioning of the Heart
The functioning of the heart consists of two types of coordinated movements that are in the atria and ventricles:
- Diastole: the blood enters the heart.
- Atrial systole: the atria contract, opening the valves.
- Ventricular diastole: the ventricles swell to receive blood.
- Ventricular systole: the ventricles contract, and the semilunar valves open.
Pulmonary Circuit
It is established between the heart and lungs. In this circuit, the blood carrying carbon dioxide comes to the right atrium through the superior and inferior vena cava.
Systemic Circuit
It is established between the heart and different organs of the body. In this circuit, the blood carries oxygen and nutrients to carry out its functions and includes carbon dioxide and wastes produced by cell metabolism. Because the circuit is longer, it is called the systemic circuit.
The Lymphatic System
The lymphatic system is responsible for collecting the excess liquid remaining between the cells, returning them to the blood, and also transporting fats that are absorbed in the intestine. It consists of:
- Lymphatic capillaries: blind, very fine small vessels distributed in all tissues.
- Lymphatic vessels: vessels similar to veins.
- Lymph nodes: small swellings that occur in the lymphatic vessels. They are also centers of formation and maturation of white blood cells. They remove foreign substances and microorganisms.
Cardiovascular Diseases
Diseases affecting the heart are called cardiovascular diseases.
- Arteriosclerosis: Hardening of the arteries is caused by the deposition of fat and cholesterol. Blockages can cause blood clots called thrombi, which can sometimes arrive at vital organs, causing thrombosis.
- Myocardial infarction: When atherosclerosis damages the coronary arteries and a thrombus occurs in one of these, blood flow is interrupted, and the muscle cells that it nurtured die, resulting in a myocardial infarction that can cause death.
Lungs eliminate carbon dioxide. The liver expels waste from digestion. Sweat glands are glands that are distributed on the skin.