Final: Gas Exchange in Animals (Respiratory System) Slides Flashcards
Functions of the respiratory system (5)
- Provides oxygen to cell
- Eliminates carbon dioxide
- Regulates pH level
- Speech production
- Defense against foreign bodies (non specific immunity)
Total atmospheric pressure and partial pressure of O2
760 mmHg; 160 mmHg
Organs of the respiratory system (10)
Nasal cavity, oral cavity, pharynx, larynx, trachea, primary bronchus, secondary bronchus, tertiary bronchus, bronchiole, alveoli
What comprises the bronchiole tree?
Primary, secondary, tertiary bronchus
Which airways are in the conducting zone?
Trachea, primary through tertiary bronchi, bronchioles
Conducting zone
Air just passing through, can’t go anywhere
Which airways are in the respiratory zone?
Respiratory bronchioles, alveoli (interact with capillaries)
Respiratory zone
Air can exchange/interact with blood
Which three types of cells make up an alveolus?
Alveolar type I cells, alveolar type II cells, macrophages
Function of alveolar type I cells
Very thin epithelial cells; form wall of alveoli
Function of alveolar type II cells
Release surfactant that prevents lung collapse and helps make breathing easy
Parts of lungs (3)
Chest wall, pleural sac, lung
Pleural sac function
Membrane that sticks lungs to inside of rib cage (allows lungs to move with ribs)
Types of pressure (3)
Atmospheric pressure (Patm), alveolar pressure (Palv), intrapleural pressure (Pip)
What is alveolar pressure?
Pressure of gases in alveoli
What causes intrapleural pressure?
Induced by pleural sac
Boyle’s Law
Pressure is inversely proportional to volume
What happens to pressure and volume during inspiration?
Volume of lungs increases, pressure decreases
What happens to pressure and volume during expiration?
Volume of lungs decreases, pressure increases
Muscle movement during inspiration
External intercostal muscles push out, diaphragm pushes down
What is passive expiration?
Elastic recoil of lungs (doesn’t use muscles)
Muscle movement during active expiration
Internal intercostals contract; abdominal muscles contract (pushes diaphragm up)
What is compliance and how does it relate to lungs?
Ease of changing the volume when pressure is changed; lungs have high compliance and expand easily
How do gases cross the lung/blood media?
Diffusion: capillaries and alveoli are lined with simple squamous epithelium
How is oxygen transported in the blood? Give breakdown.
- Dissolved in plasma and erythrocytes (1.5%)
- Bound to hemoglobin (98.5%)
How many oxygens can each hemoglobin bind?
4
Steps (overview) of oxygen transport
- O2 crosses from alveoli to plasma
- Moves from plasma to erythrocytes where it binds to Hb
- Transported to cells where it is unloaded the same way
Oxygen movement at lung level
High [O2] in alveoli, low [O2] in plasma; hemoglobin favors loading and O2 moves from alveoli to blood
Oxygen movement at tissue level
High [O2] in plasma, low [O2] in tissue; hemoglobin favors unloading and O2 moves from blood to tissue
What affects Hb-Oxygen binding?
BPG (2,3-bisphosphoglyceric acid), temperature, acidity
How is carbon dioxide transported in the blood? Give breakdown.
- Dissolved in plasma (~10%)
- Hemoglobin (~30%) - less affinity than for O2
- Bicarbonate (~60%) - a buffer
What allows most CO2 to travel in a buffer?
Carbonic anhydrase
CO2 movement at tissue level
Opposite of O2: High [CO2] in tissue, low [CO2] in blood so CO2 goes to blood
CO2 movement at lung level
Opposite of O2: High [CO2] in blood, low [CO2] in alveoli so CO2 goes to alveoli
How is inspiration initiated?
Stimulating the respiratory muscles: diaphragm and external intercostals
For inspiration, what initiates the stimulation to the respiratory muscles?
Medullary centers and pons (nervous system)
Types of chemoreceptors for respiration
Peripheral (outside brain) and central (inside brain)
What are the peripheral chemoreceptors?
Carotid bodies and aortic bodies
Homeostatic mechanism for respiration
Receptors are chemoreceptors (carotid and aortic bodies), control center is medulla and pons, effector is diaphragm and nearby muscles (external intercostals)
