Chapter 22- The respiratory system Flashcards
Gas exchange
Body tissues must be supplied with oxygen, carbon dioxide waste must be disposed of. Gasses only move in one direction during gas exchange (might not be in the same direction for every gas)
4 processes involved with gas exchange
- Pulmonary ventilation
- External respiration
- Transport of respiratory gasses to/from tissues- does not occur in the respiratory system
- Internal respiration- does not occur in the respiratory system
External respiration
Gas exchange occurring in the lungs (alveoli)
Internal respiration
Gas exchange occurring in the tissues (does not occur in the respiratory system). If PCO2 in tissues is greater than PCO2 in blood- carbon dioxide leaves tissues and enters blood. If PO2 in blood is greater than PO2 in tissues- oxygen leaves blood and enters tissue. Partial pressure and diffusion gradients are opposite to external respiration
2 zones of the respiratory system
- Conducting zone
2. Respiratory zone
Conducting zone
Respiratory passages leading from the nose to the respiratory bronchioles. Transports air to/from the lungs- no gas exchange, just movement of air
Respiratory zone
Actual site of gas exchange. Found in respiratory bronchioles, alveolar ducts, and alveoli
Upper conducting zone (2 parts)
- Nasal cavity
2. Pharynx
Nasal cavity function
Air is warmed and humidified as it passes through this cavity. Inhaling cool/dry air slows down respiration overall- warming and humidifying ensures a normal respiratory rate
Mucous membranes of the nasal cavity
Consists of the respiratory mucosa- contains 2 different types of cells. Nerve endings in membrane- invading debris triggers a sneezing reflex
2 cell types of the respiratory mucosa
- Goblet cells
2. Seromucous nasal glands
Goblet cells
Mucus producing cells. We usually only notice mucus during a cold
Seromucous nasal glands
“Mucus” portion traps particles and debris- immune function- clears pathogens. “Serous” portion secretes watery fluid containing lysozyme
Vascularization of the mucous membranes of the nasal cavity
Capillaries and veins located superficially to help warm air as it passes through- they sit very close to the surface of the membrane. This is why damage to these vessels can cause severe nosebleeds
3 regions of the pharynx
- Nasopharynx
- Oropharynx
- Laryngopharynx
Nasopharynx
Contains pharyngeal tonsils and tubal tonsil. Closes during swallowing by soft palate and uvula (dangling thing at back of throat)- stops food/liquid from getting in
Oropharynx
Meets oral cavity at the isthmus of the fauces. Contains palatine tonsils and lingual tonsils
Laryngopharynx
Where respiratory and digestive passages split. The lower conducting zone divides the laryngopharynx from the respiratory passages
Parts of the lower conducting zone (4)
- Epiglottis
- Larynx
- Trachea
- Bronchi
Epiglottis
Cartilage flap that closes off lower conducting zone. Function- separates food and air passageways
Larynx composition
Composed of cartilage- provides an open airway. Consists of thyroid cartilage and cricoid cartilage- XY individuals tend to have an Adam’s apple (testosterone makes thyroid cartilage larger and thicker). The larynx contains vocal cords for sound production
Glottis
Open passageway surrounded by vocal cords. Vocal cords are ligaments composed of elastic fibers, the fibers vibrate as we exhale to produce sound
Sound pitch vs sound loudness of vocal cords
If chords are tense, they vibrate more quickly- higher pitch. Increased testosterone usually causes the chords to be longer and looser, causing a deeper voice. Loudness increases as air is passed across the cords with greater force. Many sound properties are created by other structures- tongue, lips, etc.
Trachea composition
Windpipe. Composed of elastic fibers and cartilage rings. Elastic fibers provide flexibility- trachea can stretch/relax while breathing cartilage rings prevent the trachea from collapsing. Without the cartilage rings, the trachea and larynx would collapse between breaths. It would take a large amount of work to breathe
Trachealis
Smooth muscle tissue of the trachea, innervated. Contraction leads to diameter of the trachea decreasing and air forced upward . Ex- coughing reflexes remove things from the lungs
Bronchi
Allow air to reach the respiratory zone. The trachea branches to form 2 main bronchi, bronchi branch 20-25 times to eventually form bronchioles. Smallest of the bronchioles in the conducting zone are terminal bronchioles.
Lungs
Organ where external gas exchange occurs. Lungs composed of air space and elastic connective tissue. Lungs are elastic in nature- ensures that the lungs don’t become permanently stretched out with breathing- you would need more and more air to fill them
Hilum
Each lung has a hilum- point at which the bronchi and any blood/nerve supply enter/leave the lung
Blood supply to lungs
Pulmonary artery brings oxygen poor blood to lungs- artery branches in a similar pattern as bronchi. The pulmonary vein moves oxygenated blood away from the lungs. The pulmonary capillary network immediately surrounds alveoli- where external gas exchange takes place
Pulmonary plexus
Where nerve fibers enter the lungs
Innervation of the lungs
Lungs have both parasympathetic and sympathetic fibers. Parasympathetic causes the air tubes to constrict- if resting, you don’t need to bring in a huge amount of air. Sympathetic causes the air tubes to dilate- using your skeletal muscle tissue more, use more oxygen
Pleurae function
Thin, double layered serous membrane (visceral and parietal layers). Produces pleural fluid, which fills cavity between visceral and parietal layers. Also creates chambers for each lung.
Parietal pleura
Covers the thoracic wall and the upper portion of the diaphragm
Visceral pleura
Covers external lung features
Importance of pleural fluid
Pleural fluid fills the cavity between visceral and parietal layers. Importance- lungs can “slide” over structures as they change in size. There is a very small amount of fluid between the layers- difficult to get the layers apart. Visceral and parietal pleura are “stuck” together.
What are the benefits of having a chamber for each lung? (2)
- As organs move/shift with breathing, etc.- organs cannot interfere with others
- Prevents spread of infection from one organ to another- prevents spread to another lung or heart
Branching pattern of respiratory bronchioles
Branch from the terminal bronchioles of the conducting zone, lead into alveolar sacs composed of multiple individual alveoli.
Alveoli
Multiple alveoli are grouped into each alveolar sac. Alveoli are covered with capillary beds. Gas exchange occurs via diffusion- the walls of the alveoli are made of simple squamous epithelium, and are very thin to facilitate gas exchange. Individual alveoli connected to “neighbors” via alveolar pores- ensures that all alveoli in the sac are able to fill with air
3 cell types of alveoli
- Type 1 alveolar cells
- Type 2 alveolar cells
- Alveolar macrophage
Type 1 alveolar cells
Squamous epithelial cells. Function- creates walls of alveoli- where gas exchange and diffusion occurs
Type 2 alveolar cells functions (2)
Cuboidal cells scattered among type 1 cells, less common. Functions:
- Secrete surfactant, a detergent like substance. Surfactant prevents alveoli from collapsing as air leaves during exhalation
- Secrete antimicrobial proteins- innate immunity
Alveolar macrophage
Mobile cells, travel through the lung tissue. Function- consume debris, pathogens, etc.- protect internal alveolar surfaces
2 processes involved with respiratory physiology
- Pulmonary ventilation
2. Gas exchange
Pulmonary ventilation
The flow of air into and out of the lungs. Air flows according to a pressure gradient, from high pressure to low pressure
Gas exchange
The exchange of respiratory gasses across the alveolar wall. Respiratory gasses can move from air space in lungs to blood, or from blood to air space in lungs. The same gas will always move in the same direction.
3 gas laws influence the process of gas exchange and pulmonary ventilation
- Boyle’s law
- Dalton’s law of partial pressures
- Henry’s law
Boyle’s law
The volume of a gas is inversely proportional to the pressure exerted by the gas on the walls of its container. A gas always fills a container- as gas molecules move around and bump into each other, they create pressure. More moving around= more pressure. If you change the volume of a container filled with gas, the pressure within the container will change
How is Boyle’s law important for pulmonary ventilation?
Inhalation and exhalation changes the volume of the lungs. Changing the volume of lungs changes the pressure of air in the lungs- air moves according to pressure gradient
Pressure in the lungs always described relative to
Atmospheric pressure. At sea level, atmospheric pressure (Patm)= 760 mm Hg
Intrapulmonary pressure (Ppul)
Pressure in the alveoli. Changes as you inhale or exhale, but always equalizes Patm at some point
Which 2 muscles initiate inspiration?
- Diaphragm
2. Intercostal muscles