Unit 9: Respiration Flashcards
Upper respiratory tract: Structures in this tract and their functions
Nasal cavities: Hollow spaces in the nose; Filter, warm, and moisten air
Pharynx: Chamber located in back of throat; common passage for air & food, connects the nasal cavities to the larynx
Larynx: Passageway for air between pharynx and the trachea; houses the vocal chords for sound production
Lower respiratory tract: Structures in this tract and their functions
Trachea: commonly known as windpipe, tube connecting the larynx to the bronchi. Held open by C-shaped rings of cartilage.
Bronchi (sing. bronchus): Left and right branches off the trachea that leads into the left and right lungs. Held open by C-shaped rings of cartilage.
Bronchioles: Smaller branches of the bronchi, thus the smaller diameter no longer requires cartilage support. Leads the air to alveoli.
Alveoli (sing. alveolus): grape-like clusters of air sacs at the end of bronchioles; site of O2-CO2 exchange in the lungs
Pleural membrane
Double layer membrane that covers the surface of the lungs. Inner membrane is joined to the lung while the outer membrane is joined to the ribs and diaphragm. The two membranes are separated by a fluid that allows the lung to move easily against the thoracic cavity during inhalation/exhalation.
Thoracic cavity
The chest compartment, from the diaphragm to throat. Contains both the lungs and the heart.
Diaphragm & ribs
Horizontal muscle that separates the thoracic cavity from the abdominal cavity.
Protects internal organs
Role of mucous and cilia
Filters oxygen; Mucus gland and cilia and lined along the walls of the trachea and bronchi. Any material other than gasses are caught in the mucous. The cilia are in constant motion that pushes the mucous full of debris upward towards the pharynx, where the material is swallowed or coughed/spat back out.
Structure of alveoli and its specializations
- Numerous: provides a large surface area for diffusion
- One epithelial cell thick: results in a very short distance for gases to diffuse between the alveoli and the capillaries
- Coated with lipoprotein: lowers surface tension, preventing the alveoli to collapse during exhalation
Inhalation process
- Respiratory centre in the medulla oblongata automatically sends out nerve impulses that causes the diaphragm and the intercostal muscles within the rib cages to contract
- Diaphragm contracts and moves down, while the intercostal muscles contract that moves the rib cage up and out. This increases the volume of the thoracic cavity, which in turn lowers the pressure in the lungs.
- Partial vacuum is created as the pressure inside the lungs is less than the pressure outside of the lungs.
- Air rushes into the lungs to rebalance the pressure.
Inhalation is by negative pressure, as the temporary vacuum in the lungs draw in air until the air pressure in the alveoli is equal to the air pressure in the atmosphere.
Exhalation process
- Elastic properties of the thoracic wall and lungs cause them to recoil and relax
- Diaphragm relax and moves up, while the intercostal muscles relax and moves the rib cage down and in.
- Thoracic cavity volume decreases, which in turn increases the pressure in the lungs.
- Unlike inhalation, air is forced out of the lungs due to positive pressure.
Nervous input that affect ventilation
Alveoli are supplied with stretch receptors. These nerve endings are sensitive to stretch. When the alveoli are full enough/stretched by the air, the receptors signal the respiratory center to stop sending out nerve impulses and initiates exhalation.
Chemical inputs that affect ventilation
High CO2/H ion concentration: The rise in these levels in the blood alerts the respiratory center to increase the rate and depth of inhalation. The respiratory center is not directly affected by oxygen levels.
Low oxygen levels: Chemoreceptors in carotid and aortic bodies are sensitive to oxygen levels. Decrease in oxygen concentration causes these bodies to communicate with the respiratory center that ultimately increases the rate and depth of inhalation.
Partial pressure
The amount of pressure gases exert. Each pressure is represented by PO2 and PCO2
External respiration (define and explain the pattern for each gases)
Exchange of gases at the lungs
O2:
1. Blood in the pulmonary capillaries is low in oxygen and the air in alveoli contains a higher PO2.
2. O2 diffuses into plasma and then into red blood cells.
3. O2 joins with hemoglobin to form oxyhemoglobin
CO2:
1. Reduced hemoglobin releases its H ions
2. H ions are picked up temporarily by bicarbonate ions to make carbonic acid which dissociates into CO2 and H20. Enzyme carbonic anhydrase speeds up this reaction.
3. Carbaminohemoglobin breaks down to hemoglobin and CO2.
4. The broken down CO2 and dissolved CO2 diffuse into alveoli due to PCO2 differences.
5. CO2 is expelled through exhalation.
Internal respiration (define and explain the pattern for each gases)
Exchange of gases at the tissues
O2:
1. Oxygen is released from oxyhemoglobin
2. PO2 of tissue fluid is lower than that of blood, since tissue cells continuously use up oxygen during cellular respiration
3. Oxygen diffuses into the tissues
CO2:
1. PCO2 of tissue fluid is higher than that of blood, since CO2 is continuously produced by cells as waste.
2. 9% of CO2 diffuses into blood as dissolved CO2.
3. 27% of CO2 binds to hemoglobin to form carbaminohemoglobin
4. 64% of CO2 joins with water to temporarily make carbonic acid, which dissociates into H ions and bicarbonate ions. Enzyme carbonic anhydrase speeds up this reaction.
5. Most of H ions are picked up by hemoglobin to form reduced hemoglobin. Hemoglobin acts as a buffer.
Chemical equations for internal respiration
Formation of carbaminohemoglobin:
Hb + CO2 -> HbCO2
Formation and dissociation of carbonic acid:
(Carbonic anhydrase)
CO2 + H20 -> H2CO3 -> H(+) + HCO3(-)
Formation of reduced hemoglobin
H(+) + Hb ->HHb
Oxygen released from hemoglobin:
HbO2 -> Hb + O2
