Transcript of "Respiratory system and gaseous exchange"
UNIT 9:RESPIRATORY SYSTEM AND GASEOUS EXCHANGE
BREATHING• Sequence of events that results in gas exchange.• In terrestrial vertebrates it includes 3 steps: 1. Ventilation: Inspiration and expiration. 2. External respiration: Gas exchange between air (in lungs) and blood. Blood then transport Oxygen to the body tissue cells. 3. Internal respiration: Gas exchange between blood and tissue fluid. Blood then transports carbon dioxide to the lungs.
Gas exhange surfacemust be: Alveoli filled with air (gas) External•Moist respiration Carbon dioxide oxygen•Thin•Large in relation of sizeof body Blood – part of circulatory system contain red pigment – Process: Diffusion of hemoglobin, to gasses (oxygen and transport gasses carbon dioxide Internal respination oxygen Carbon dioxide Body cells surrounded by tissue fluid
Cellular respiration• Is the process whereby an organism uses oxygen and food to produce energy (ATP) and 2 by products e.g. water and carbon dioxide• Glucose + O2 ATP + H2O + CO2Therefore gaseous exchange is necessary to get oxygen for cellular respiration.
HUMAN RESPIRATORY SYSTEM• Consists of: 1. Nose 2. Air passages: Pharynx Trachea Bronchus Bronchioles3. Lungs – Alveoli
• Nose has a nasal cavity that leads to the pharynx.• Nasal cavity is lined with cilia NOSE and hairs and goblet cells that make mucus (anti-septic and moisten air)– filter the air – dust, pollen and other foreign material sticks to it.• 3 x turbinate bones divide the nasal cavity into 4 passages – This enlarges the surface of the nasal cavity – For warming, cleaning and moisten of air.• Several surface blood vessels help to warm air.
AIRPASSAGES• Pharynx – pass air form nose to trachea via larynx.• Trachea: long, straight tube kept open by C- shaped cartilage rings.• Trachea – lined with cilia and goblet cells (mucus production) – traps foreign particles
Lining of airpassagesCILIA (SEM) TRACHEAL LINING
AIRPASSAGES: BRONCHI AND BRONCHIOLES• Trachea divides in a right and left bronchus – consist of C-shaped cartilage rings and lined Right bronchus-short with goblet cells (mucus) Branch in 3 Left bronchus – long,• Bronchi branch in lung to branch in 2 form bronchioles – branch further and cartilage rings disappears – lead air to air sacs of lung. Bronchiole
LUNGS• Right lung (3 lobes - shorter) and left lung (2 lobes – longer, narrow)• Spongy, elastic pink organ.• Consists of several air sacs called alveoli.• Alveoli are grouped together and form the endings of the bronchioles.
ALVEOLI• Lined with single layer squamous epithelial cells – Thin easy diffusion of gas.• Alveoli is surrounded by a network of blood capillaries – gasses diffuse into and out of blood.• Alveoli is lined with moist layer – oxygen dissolves in moisture and diffuses through alveoli wall into blood capillary.
Pulmonary vein Pulmonary artery (Oxygenated (Deoxygenated blood) blood)Turbinate bones Pharynx Alveoli Trachea BronchusBronchioleDiaphragm SEM TEM
BREATHING - The process whereby air (gasses) move in and out of the body. EXPIRATION INSPIRATION • INSPIRATION Air inhaled • EXPIRATION Air exhaledRib cageexpands as Rib cage getsrib muscles smaller as ribcontract muscles relax When pressure in lungs increase – air isWhen pressure in pushed out Diaphragm Diaphragmlungs decrease – air contracts (moves relaxes (movesrush in down) up)
TIDAL VENTILATION MECHANISM• Air moves in and out of the body via the same route.• All terrestrial vertebrates do this except for birds.• The lungs are not completely emptied during each breathing cycle.• The air entering mixes with used air remaining in the lungs.• This help to conserve water, but decreases gas- exchange efficiency
Determining lung capacity• A spyrometer can be used to determine how much air enters the lungs.• Your lungs has a volume of +/- 5 liters.• During a normal breath, only 0.5 liters of air is exchanged – This air is known as tidal volume.• During forced breathing, as much as 3.5 liters of air can be exchanged, this is known as vital capacity. (The fitter you are, the higher your vital capacity.)• +/- 1.5 liters of air always remains in the lungs – this air is known as residual air/volume.
RESPIRATORY CENTER• Normal breathing rate for adults: 12 – 20 ventilations per minute.• Respiratory Center in the Medulla Oblongata of the brain controls breathing.• The respiratory center send impulses through the phrenic nerve to the diaphragm and through the intercostal nerve to the intercostal muscles to either contract or relax. (Contract during inspiration and relax during expiration)
Nervous control of breathing Brain Respiratory center automatically regulates breathing Intercostal nerves stimulate the intercostal muscles Intercostal musclesPheric nerve stimulates thediaphragm Diaphragm
GAS EXCHANGE• Gas exchange between air in lungs and blood EXTERNAL RESPIRATION INTERNAL RESPIRATION• Movement driven by diffusion • Gas exchange between gradient. (  to ) blood and tissue fluid• Gasses exerts pressure, the • Movement driven by amount of pressure each gas diffusion gradient. (  to exerts is called – partial ) pressure (PO2 and PCO2) • Gasses exerts pressure, the amount of pressure each gas exerts is called – partial pressure (PO2 and PCO2)
EXTERNAL RESPIRATSION• If PO2 differs across a membrane – oxygen will diffuse from a high to a low pressure.• If PCO2 differs across a membrane – carbon dioxide will diffuse from a high to a low pressure.• During inspiration the alveoli fills with air – higher PO2 and lower PCO2 than blood.• Oxygen diffuse from alveoli into blood and carbon dioxide diffuse from blood into alveoli.
INTERNAL RESPIRATION• When blood reaches the tissue, cellular respiration in cells causes the tissue fluid to have a lower PO2 and a higher PCO2 than the blood.• Thus oxygen diffuse from a high pressure in the blood to a low pressure in the tissue fluid and eventually in the tissue cells.• Carbon dioxide diffuse from a high pressure in the tissue fluid to a low pressure in the blood.
TRANSPORT OF OXYGEN• Most oxygen is transported by hemoglobin (red pigment protein in erythrocytes).• Oxygen combines with hemoglobin to form oxyhemoglobin. Hb + O2 = HbO2 Hemoglobin Oxygen Oxyhemoglobin• A small amount of oxygen is transported in solution in the blood plasma.
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