Second, human nutrition.
1, nutrients in food
1) protein: the basic substance that constitutes human cells and provides energy for human physiological activities;
Sugar: the most important energy-supplying substance in human body, and also a component of cells;
Fat: energy-supplying substance, which releases the most energy per unit mass; But in general, fat is stored in the body as a spare energy substance;
Vitamins: do not participate in the formation of human cells, do not provide energy, the content is very small, and play a regulatory role in human life activities.
Vitamin A: Promote the normal development of human body, enhance resistance and maintain normal vision.
Lack, rough skin and night blindness.
Vitamin B 1: Maintain normal metabolism of human body and normal physiological function of nervous system.
Deficiency, neuritis, beriberi
Vitamin C: Maintain normal metabolism, maintain normal physiological functions of bones, muscles and blood vessels, and enhance resistance.
When lacking, scurvy and resistance decrease.
Vitamin D: Promote calcium and phosphorus absorption and bone development.
When lacking, rickets (such as chicken breast, X-shaped or O-shaped legs, etc. ) and osteoporosis
Water: about 60%~70% of body weight. It is the main component of cells, and all kinds of physiological activities of human body are inseparable from water.
Inorganic salts: important substances that constitute human tissues, such as:
Calcium: lack of children leads to rickets, chicken breasts, O-legs, osteoporosis in middle-aged and elderly people,
Phosphorus: deficiency leads to anorexia
Iron: constitutes hemoglobin, lack of which leads to anemia.
Iodine deficiency: goiter or mental retardation in children.
2. Digestion and absorption
1) Composition of digestive system
Digestive tract: oral cavity, pharynx, esophagus, stomach, small intestine, large intestine and anus.
The digestive system digests food and absorbs nutrients.
Digestive glands: salivary glands, stomach glands, liver, pancreas and intestinal glands.
The liver secreting digestive juice is the largest digestive gland in human body, secreting bile and participating in fat digestion.
2) Structural characteristics of small intestine:
The main place to digest food and absorb nutrients.
Intestinal wall structure (from inside to outside): mucosa, submucosa, muscle layer and serosa.
The small intestine is suitable for digestion and absorption;
A) the longest;
B) There are folds and small intestinal villi on the inner surface (greatly increasing the area of digestion and absorption);
C) There are capillaries and lymphatic capillaries in the villi of small intestine. The walls of villi, capillaries and lymphatic capillaries are very thin, and they are only composed of a layer of epithelial cells, which is beneficial to absorb nutrients;
D) there are various digestive juices.
3) Digestion of food: the process that food breaks down into absorbable components in the digestive tract.
Physical digestion: chewing teeth, stirring tongue and gastrointestinal peristalsis, grinding and stirring food and mixing it with digestive juice.
Chemical digestion: through the action of various digestive enzymes, various components in food are decomposed into absorbable nutrients.
Salivary amylase (intestinal juice, pancreatic juice)
Starch digestion (oral cavity, small intestine): starch maltose glucose
Enzymes (gastric juice, pancreatic juice, intestinal juice)
Digestion of protein (stomach, small intestine): protein amino acids
Bile (liver) enzyme (intestinal juice, pancreatic juice)
Digestion of fat (small intestine): fat granule glycerol+fatty acid
Bile contains no digestive enzymes.
4) absorption of nutrients: the process of nutrients entering the circulatory system through the digestive tract wall.
Stomach: a small amount of water and alcohol (non-nutritive)
Small intestine (main absorption site): glucose, amino acids, glycerol, fatty acids, most water, inorganic salts and vitamins.
Most of the fat components are absorbed from the lymphatic capillaries (lymphatic blood circulation) of intestinal villi; Others enter the blood circulation from the capillaries of intestinal villi.
Large intestine: a small amount of water, inorganic salts and some vitamins.
3. Pay attention to reasonable nutrition and food safety.
1) Eat on time with reasonable nutrition.
Not partial to food, not picky about food, not overeating.
Balanced intake of five foods (balanced diet pagoda)
2) Food safety Vegetables and fruits must be cleaned.
Don't eat poisonous food (rotten food, sprouted potatoes)
Buy food that has passed quarantine inspection.
Keep the kitchen and cooking utensils clean.
Third, the human body's breathing
1, respiratory air treatment
1), composition of respiratory tract:
Respiratory tract: nasal cavity, pharynx, larynx, trachea and bronchus
The passage of gas in and out of the lungs in the respiratory system cleans, moistens and warms the inhaled gas.
Lung: a place for gas exchange
2), lungs
(1) location: in the chest cavity, one on the left and one on the right.
(2) Structure: The outer alveoli are surrounded by capillaries, and the walls of the alveoli and capillaries are very thin, only consisting of a layer of epithelial cells, which is suitable for gas exchange.
(3) Function: gas exchange
2. Gas exchange in the lungs
1) Respiratory movements include inhalation and exhalation.
2) Changes of external intercostal muscles, diaphragm, ribs, sternum, thorax and lungs when people breathe quietly;
3) Principle: Breathing muscles contract and relax, the chest expands and contracts, and the lungs passively expand and contract to form a pressure difference, thus inhaling and exhaling.
4) gas exchange in the body:
carbon dioxide
(2) gas exchange in alveoli: blood alveoli
oxygen
oxygen
(3) gas exchange in tissues: blood tissue cells
carbon dioxide
3. Air quality and health
1) Air quality affects human health, and pollutants in the atmosphere are extremely harmful to human health.
Harmful substances can cause respiratory diseases.
2) Understand the local air quality and the causes of local air pollution.
Measuring dust particles in the air
Four, the transport of substances in the human body
1, flowing tissue-blood
1) Blood composition and function
Plasma components: water, protein, glucose, inorganic salts, etc.
Function: Carrying blood cells, transporting nutrients and wastes.
erythrocyte
Blood cell leucocyte
blood platelet
Species, morphological characteristics, normal values, dysfunction
Both sides of red blood cells are depressed, and the average number of male seedless cells in mature red blood cells is 5.0 *1012/l; Female: 4.2* 10 12/L transport oxygen and a part of carbon dioxide anemia.
White blood cells are larger than red blood cells, with a nucleus of 4~ 10* 109/L, which has a defensive and protective effect on human body and inflammation.
Platelets are small in size and irregular in shape, with no nucleus 100~300* 109/L to stop bleeding and accelerate coagulation.
Hemoglobin: A red iron protein contained in red blood cells.
Features: It combines with oxygen in places with high oxygen content and separates from oxygen in places with low oxygen content.
Functions of blood: transportation, defense and protection, and temperature regulation.
2, blood flow pipeline-blood vessels
1) Types, structures and functions of blood vessels
Structural characteristics of species functional distribution
Arteries carry blood from the heart to all parts of the body. Deep blood vessel, thick wall, great elasticity, small lumen and fast blood flow.
Veins send blood back to the heart from all parts of the body. Blood vessels are deep or shallow, with thin walls, small elasticity and large lumen. There are venous valves in the veins of limbs, and the blood flow rate is slow.
Capillary connects the blood vessels between the smallest artery and the smallest vein, which are widely distributed throughout the body. The tissue wall is extremely thin and consists of a layer of epithelial cells. Only red blood cells are allowed to pass in a single row, and the blood flow rate is the slowest.