Biological knowledge points of seventh grade in Beijing Normal University: blood circulation, blood flow channels and blood vessels.
Type distribution, functional structure characteristics
Blood flow velocity in elastic cavity of tube wall
Arteries are located deep in the body and carry blood from the heart to the whole body. They are thick, small and fast.
Deep veins or superficial veins send blood from the whole body back to the heart, which is thin and small (limbs have valves) and slow.
Blood and tissue cells outside the capillary exchange substances here, which are extremely thin (composed of only one room of epithelial cells), tiny and extremely slow (only red blood cells are allowed to pass through in a single line).
Second, the power organ of blood transport, the heart (located in the middle of the chest to the left)
Four chambers of the heart and connected blood vessels;
Left ventricle aorta right ventricle pulmonary artery left atrium pulmonary vein right atrium superior and inferior vena cava
The left ventricular wall is the thickest.
Location, opening direction and blood flow direction of atrioventricular valve, arterial valve and venous valve:
The open position ensures the direction of blood flow.
The atrioventricular valve opens the atrium to the ventricle between the atrium and the ventricle? room
Between the aortic valve and the artery, open the ventricle to the artery? artery
The venous valve opens the vein in the direction of the limb vein to the heart? external ear
When the ventricle contracts, the atrioventricular valve closes and the arterial valve opens. When the ventricle relaxes, the arterial valve closes and the atrioventricular valve opens. There's no valve in the artery.
Output per minute = output per stroke х heart rate (75 beats per minute)
The output per minute, also called cardiac output, is an index to measure the working energy of the heart.
Cardiac cycle (0.8S)=60 seconds (one minute)? Heart rate Every contraction and relaxation of the heart is a cardiac cycle.
In a cardiac cycle, the advantages of diastolic period being longer than systolic period are as follows:
1) is beneficial to blood return to the heart.
2) Make the myocardium have enough time to rest.
Blood circulation path
Systemic circulation pathway: left ventricle? Aorta? Various parts of the body and visceral capillaries? Superior and inferior vena cava? right atrium
Pulmonary circulation path: right ventricle? Pulmonary artery? Pulmonary capillaries? Pulmonary vein? left atrium
1) Each cycle begins in the ventricle and ends in the atrium.
2) Arterial blood flows out of systemic circulation and venous blood returns; Venous blood flows out of the pulmonary circulation and arterial blood flows back.
3) Two circulations are carried out at the same time, and finally meet in the heart to form a complete circulatory pathway.
4) At the capillaries of tissues and cells in the whole body: blood changes from arterial blood to venous blood.
At the capillaries of the lungs: blood changes from venous blood to arterial blood.
5) Arterial blood flows on the left side of the heart and venous blood flows on the right side.
Third, blood pressure and pulse.
Blood pressure: the lateral pressure on the blood vessel wall when blood flows forward in the blood vessel.
What we usually call blood pressure is the arterial blood pressure of systemic circulation.
Its expression is: systolic blood pressure/diastolic blood pressure.
It can be measured with a sphygmomanometer at the brachial artery of the upper arm. Its value is usually expressed in kilopascals.
When the heart contracts, the highest value of arterial blood pressure is called systolic pressure. The lowest diastolic arterial blood pressure is called diastolic blood pressure.
The normal systolic blood pressure of healthy adults is 12 ~ 18.7 kPa, and the diastolic blood pressure is 8 ~ 12 kPa.
Pulse refers to the pulse of the artery, the frequency is the same as the heart rate, but the meaning is different. Measured in the radial artery.
The seventh grade biology knowledge of Beijing Normal University: the release of energy in food 1. Energy is stored in food.
1, heat price: the energy released by each gram of food when it is fully burned in vitro.
2. Sugar: 17. 15KJ
Protein: 23.43KJ
Fat: 38.9 kJ
3. The energy needed for human life activities mainly comes from sugar, followed by fat.
Second, cells release energy through breathing.
1. The process of oxidative decomposition and energy release of glucose in biological cells is respiration.
2. The meaning of breathing is to provide power for life activities.
Biological knowledge points of the seventh grade of Beijing Normal University: the process of obtaining oxygen by human cells 1. The respiratory tract and lungs constitute the respiratory system.
1, the human respiratory system consists of respiratory tract and lung.
2, respiratory tract: (nose, pharynx, larynx, trachea, bronchus) is the passage of gas in and out of the lungs.
Lung: a place for gas exchange with the outside world, located in the chest, one left and one right, consisting of dendritic branches of bronchioles and alveoli.
3. Nose and nasal cavity (including capillaries and mucous glands rich in mucous membranes): make the air inhaled into the nasal cavity warm and moist.
4. Throat
(1) pharynx: Qi and food are the same.
(2) Laryngeal: It consists of cartilage and vocal cords.
5, trachea (bronchus): supported by C-shaped cartilage, there are mucus glands on the wall of the tube, and the secreted mucus can adhere to dust; There are cilia on the inner surface of the tube wall, and the cilia swing to push the mucus to the throat and excrete it through coughing. (phlegm)
6, lung (the main organ of the respiratory system, an important place to complete gas exchange)
Alveolus: ① There are many alveoli with a large total area; ② There are abundant capillaries and elastic fibers around alveoli; ③ Alveolar wall and capillary wall are thin, only composed of monolayer cells, which are very suitable for gas exchange.
Second, respiratory exercise and lung ventilation.
Inhalation: Diaphragm contracts, diaphragm top descends, chest volume expands, lung volume increases, gas pressure in lung decreases correspondingly, and gas is inhaled;
Exhale: Diaphragm relaxes, diaphragm top rises, chest volume decreases, lung volume decreases, gas pressure in lung increases correspondingly, and gas is discharged.
Conceptual realization means representation means result.
The process of gas exchange between the outside world and alveoli: breathing, exercise, exhalation and inhalation.
The exchange of oxygen and carbon dioxide occurs between the alveoli of the lungs and the blood, and the gas diffuses oxygen.
Alveolar blood
Carbon dioxide venous blood becomes arterial blood.
Exchange of oxygen and carbon dioxide between blood and tissue cells. This gas diffuses oxygen.
Blood tissue cells carbon dioxide arterial blood changes venous blood