2The Human Respiratory System The human respiratory system is made up of lungs and a system of air tubes that carry air to and from the lungs.LUNGS are the gas exchange organs in air-breathing vertebrates and in some other animals.DIAPHRAGM is a muscle that forms the floor of the chest cavityPLEURA each lung is covered with a two-layered membrane called pleura.
3The Human Respiratory System Air passes through;The nose Pharynx Larynx TracheaBronchiBronchial tubesBronchiolesAlveoli
6The Human Respiratory System THE NOSE:air enters through nostrilsthe spaces in the nose are called nasal passageshairs stop foreign substances from enteringthe wall of the nasal passages are covered with;Mucous membraneCells that have ciliaThey both trap bacteria, dust, and particlesmoistens air
7The Human Respiratory System THE PHARYNX:from the nasal passages, air travels through the pharynx (throat)it connects the nasal cavity and oral cavity to larynxtonsils form a protective barrier at the junction of pharynx and oral cavity
8The Human Respiratory System THE LARYNX: (VOICEBOX)it is mainly made up of cartilagevocal cords are two pairs of membranes streched across the inside of the larynxas air is breathed out, the vocal cords vibrate
9The Human Respiratory System Epiglottis:To prevent chocking during swallowing food and liquids are blocked from entering the opening of the larynx by the epiglottis.
10The Human Respiratory System TRACHEA:is made up of smooth muscle, cartilage and mucous membraneit’s always open by cartilage ringsinside of it is lined with ciliated mucous membrane
11The Human Respiratory System BRONCHI:in the middle of the chest cavity, trachea branches into two bronchi.they are made up of cartilage and lined with ciliated cells.when they enter the lungs, they form the bronchial tubesBRONCHIOLES:the bronchial tubes divide and subdivide, finally they become a group of tiny tubes called bronchioles
12The Human Respiratory System ALVEOLI:each bronchiole ends in a tiny air chamber that looks like a cluster of grapeseach chamber contains several cup-shaped cavities called alveolithe walls of the alveoli is only one cell-thick and they are the respiratory surfacethey are moist and surrounded by large no. of capillariesthe exchange of O2 and CO2 between air and blood takes place through the capillaries.
14Gas Exchange in HumansGas exchange in humans can be divided into 4 stages;*Breathing is the movement of air into and out of the lungs*External respiration is the exchange of O2 and CO2 between the air and the blood in the lungs*Internal respiration is the exchange of O2 and CO2 between the blood and the body cells*O2 and CO2 transport is the movement of gases between the lungs and other body parts
15DURING INHALATION (INSPIRATION) DURING EXHALATION (EXPIRATION) The diaphragm muscles contract and pull it downThe diaphragm muscles relax, allowing the diaphragm to return to its domed shape (upward-arched)The intercostal (rib) muscles contract and pull the rib cage up and out.The intercostal (rib) muscles relax, allowing the ribs to move downwards under their own weight.Chest (thoracic) cavity volume increasesChest (thoracic) cavity volume decreasesPressure in the cavity decreases as (compared to atmosphere)Pressure in the cavity increases (as compared to atmosphere)Air is sucked into the respiratory tract & lungsAir is forced out through the system.AN ACTIVE PROCESSA PASSIVE PROCESS
16The rate and depth of breathing is increased Control of BreathingBreathing is mostly involuntary and it’s controlled by respiratory center in the brain.When [CO2 ] increases in bloodChemoreceptors on aorta and some arteries detect changesRespiratory center in the brain is stimulatedNerves carry impulses toThe rate and depth of breathing is increased[CO2 ] is lowered in the bloodDiaphragm and chest muscles
17Control of Breathing***CO2 and lactic acid that is formed during heavy exercise increases the acidity of blood and stimulates respiratory center to increase breathing.
19External and Internal Breathing External Respiration is the exchange of O2 and CO2 between the air and the blood in the lungs.After inhalation, the amount of O2 in the alveoli is higher than in the bloodThen diffuses into blood that is the region where [O2] is lowerSo O2 dissolves into moist lining of alveoliAs the blood is pumped from heart, O2 rich blood from lungs is carried to body tissues
20External and Internal Breathing Blood that is rich in CO2 from body tissues is returned to lungsThen diffuses into blood that is the region where [O2]In the lungs, the amount of CO2 in the blood is higher than the CO2 in the alveoliCO2 diffuses out of the blood into the alveoli
21External and Internal Breathing Internal Respiration is the exchange of O2 and CO2 between the blood and the body cells.In the capillaries of the body tissues, O2 diffuses from blood the body cells.CO2 diffuses out of the cells into the blood.***Each gas diffuses down a concentration gradient, that is each gas diffuses from a high concentration area to a low concentration area.
22O2 and CO2 Transport Oxygen Transport 98% of oxygen is carried from lungs to body tissues by the hemoglobin in RBCs. (Hemoglobin holds O2 loosely)Hb O HbO 2(Hemoglobin) (Oxyhemoglobin)2. 2% of oxygen is transported by blood plasma as dissolved O2
23O2 and CO2 Transport** The amount of oxygen in the surrounding tissues determines whether hemoglobin will combine with oxygen or will release oxygen.Hemoglobin combines with O2 to form oxyhemoglobinWhen blood reaches to body cells, amount of O2 in the surrounding is lowIn the lungs there is large amount of O2Oxyhemoglobin breaks down into oxygen and hemoglobin
26O2 and CO2 Transport Carbondioxide Transport 70% of CO2 is transported in blood is carried in blood plasma.CO H2O H2CO3Carbonic anhydraseH2CO3 quickly breaks down into H+ ions and HCO3H2CO H HCO3-(is held by (bicarbonate ionshemoglobin) diffuses into plasma)forms quickly by the enzyme found in RBCs
27O2 and CO2 Transport2. 20% of carbondioxide is transported by RBCs as carboxyhemoglobin.CO Hb HbCO2 (carboxyhemoglobin)3. 10% of carbondioxide that diffuses into blood is transported by blood plasma as dissolved CO2.