Exam 4: Respiratory System Flashcards
Respiration Definition
•collective process by which oxygen and carbon dioxide are continuously exchanged between the atmosphere and the body’s cells
What does the respiratory system provide?
gas exchange
•Aerobic cellular respiration is necessary for life: what does it require?
–Requires an uninterrupted supply of oxygen
–Requires removal of carbon dioxide waste
What do cells do in the respiratory system?
engage in aerobic cellular respiration
Systems Working together to produce respiration: Respiratory
–promotes gas exchange between the lungs and atmosphere
Systems Working together to produce respiration: Skeletal and Muscular
–facilitate movement of air in and out of lungs
Systems Working together to produce respiration: Nervous
coordinates contraction of muscles for breathing
Systems Working together to produce respiration: cardiovascular
–transports oxygen and carbon dioxide between lungs and cells
Anatomy: Structurally: Upper Respiratory System
•Nose, pharynx and associated structures
Anatomy: Structurally: Lower Respiratory System
•Larynx, trachea, bronchi and lungs
Anatomy: Functionally: Conducting Zone
–conducts air to lungs
•Nose, pharynx, larynx, trachea, bronchi, bronchioles and terminal bronchioles
Anatomy: Functionally: Respiratory Zone
–– main site of gas exchange
•Respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli
Functions of the Nose
–Cleans incoming air
–Humidifies incoming air
–Modification of speech vibrations
–Olfaction- detection of odorants
What is the Pharynx commonly called?
Throat
What are the lateral walls of the pharynx composed of?
Skeletal Muscles
What are the three parts of the pharynx?
Nasopharynx
Oropharynx
Laryngopharynx
Functions of the pharynx
- Passageway for air and food
- Resonating chamber
- Houses tonsils
What is the larynx also called
voice box
What are the functions of the larynx?
•Air passageway
–Normally the larynx is open
•Prevents ingested materials from entering the respiratory tract
–During swallowing the superior opening covered
•Produces sound for speech
Vocal Cords
Ligaments in the larynx that vibrate when air passes over them during expiration
Trachea is also known as the
windpipe
where does the trachea divide into right and left primary bronchi?
Superior border of T5
What is particular about the hyaline cartilage in the esophagus
16-20 C- Shaped rings
open part faces the esophagus
Layers of the Tracheal Wall (inner most to outter most)
–mucosa
–submucosa
–tracheal cartilage
–adventitia
Mucosa
•pseudostratified ciliated columnar epithelium and a lamina propria
Submucosa
•areolar connective tissue with blood vessels, nerves, serous and mucous glands, lymphatic tissue
Adventitia
•elastic connective tissue
Bronchi: Where do the right and left primary bronchus go to?
lungs
Bronchi: Carina
–internal ridge of mucosal covered cartilage at the bifurcation
•Most sensitive area for triggering cough reflex
Division of Bronchial Tree
- Secondary lobar bronchi (one for each lobe)
- Segmental bronchi,
- bronchioles
- terminal bronchioles
- Respiratory bronchioles (respiratory zone)
Structural changes with branching
- Mucous membrane changes
- Incomplete rings become plates of cartilage and then disappear
- As cartilage decreases, smooth muscle increases
–Sympathetic ANS – relaxation/ dilation
–Parasympathetic ANS – contraction/ constriction
Lungs: What are the seperated by?
–Separated from each other by the heart and other structures in the mediastinum
What is each lung enclosed by?
–by double-layered pleural membrane
- Parietal pleura
- Visceral pleura
Parietal pleura
lines wall of thoracic cavity
Visceral Pleura
•covers lungs themselves
pleural cavity
–space between layers
•Pleural fluid reduces friction, produces surface tension (stick together)
cardiac notch
–heart makes left lung 10% smaller than right
Respiratory Zone: What is it composed of?
•respiratory ducts, alveolar ducts, and alveoli
Respiratory Bronchioles
Subdivided to alveolar ducts
Alveolar ducts
lead to alveolar sacs (clusters of alveoli)
Alveoli
Saccular outpouchings
Respiratory Zone: Epithelium
–Respiratory bronchioles lined with simple cuboidal epithelium
–Alveoli and alveolar ducts lined by simple squamous
–Thinner than in the conducting portion
•facilitates gas exchange
What are the Cell Types of the Alveolar wall?
–Simple squamous alveolar type I cells
–Alveolar type II cells (septal cells)
–Alveolar macrophage (dust cells)
–Simple squamous alveolar type I cells
- 95% of alveolar surface area
- form part of the thin barrier separating air from blood
- moist environment makes prone to collapse (high surface tension)
–Alveolar type II cells (septal cells)
- almost cuboidal shaped
- secrete pulmonary surfactant, an oily substance
–coats inner alveolar surface
–helps oppose the collapse of alveoli
–Alveolar macrophage (dust cells)
- leukocytes that engulf microorganisms
- either fixed in alveolar wall or free to migrate
Respiratory gas exchange steps
- Pulmonary ventilation/ breathing
- External (pulmonary) respiration
- Internal (tissue) respiration
Pulmonary Ventilation/Breathing
- Inhalation and exhalation
- Exchange of air between atmosphere and alveoli
External Respiration
Exchange of gases between alveoli and blood
Interal Respiration
- Exchange of gases between systemic capillaries and tissue cells
- Supplies cellular respiration (makes ATP)
Inhalation is active contraction of
Diaphragm
External Intercostals
Accessory Muscles for deep, forceful inhalation
Diaphragm
–most important muscle of inhalation
- Flattens, lowering dome when contracted
- Responsible for 75% of air entering lungs during normal quiet breathing
External Intercostals
•Contraction elevates ribs
25% of air entering lungs during normal quiet breathing
When the thorax expands:
–parietal and visceral pleurae adhere tightly due to subatmospheric pressure and surface tension – pulled along with expanding thorax
As lung volume increases
alveolar (intrapulmonic) pressure drops
Exhalation
pressure in lungs is greater than the atmospheric pressure
What is normally passive exhalation and what is it based on?
muscles relax instead of contract: it is based on the elastic recoil of chest wall and lungs from elastic fibers and surface tension of alveolar fluid.
Diaphragm relaxes and becomes dome shaped
External Intercostals relax and ribs drop down
When is exhalation active only?
during forceful breathing
What is Dalton’s Law?
–Each gas in a mixture of gases exerts its own pressure as if no other gases were present
–Pressure of a specific gas is partial pressure Px
–Total pressure is the sum of all the partial pressures
- Atmospheric pressure (760 mmHg) = PN2 + PO2 + PH2O + PCO2 + Pother gases
According to dalton when does gas diffuse across a permeable membrane?
–where its partial pressure is greater to the area where its partial pressure is less
–The greater the difference, the faster the rate of diffusion
Henry’s law
•Quantity of a gas that will dissolve in a liquid is proportional to the partial pressures of the gas and its solubility
According to Henry’s Law, higher partial pressure of a gas over a liquid and higher solubility will do what to the gas?
more of the gas will stay in solution
Why does very little N2 dissolve in the blood?
We mostly breathe in N2 but little is dissolved in the blood because of low solubility
Why is more CO2 dissolved in blood rather than O2?
CO2 is 24 times more soluble
External Respiration: Oxygen
–Oxygen diffuses from alveolar air (PO2 105 mmHg) into blood of pulmonary capillaries (PO2 40 mmHg)
–Diffusion continues until PO2 of pulmonary capillary blood matches PO2 of alveolar air
External Respiration: Oxygen
What drops PO2 of blood in pulmonary veins to 100 mmHg?
Small amount of mixing with blood from conducting portion of respiratory system
What does Gas Exchange depend on?
–Partial pressures of gases
–Surface area available for gas exchange
–Diffusion distance
–Molecular weight and solubility of gases
What is important in gas exchange when reffering to Partial pressures of gasses?
•Alveolar PO2 must be higher than blood PO2 for diffusion to occur – problem with increasing altitude
Why is molecular weight and solubility of gases important to gas exchange?
•O2 has a lower molecular weight and should diffuse faster than CO2 except for its low solubility - when diffusion is slow, hypoxia occurs before hypercapnia
Oxygen Transport:
The higher the PO2….
more O2 combies with Hb
Oxygen Transport:
To be fully saturated means
completely converted to oxyhemoglobin
Oxygen Transport:
What does percent saturation express
average saturation of hemoglovin with oxygen
Oxygen-hemoglobin dissociation curve
- In pulmonary capillaries, O2 loads onto Hb
- In tissues, O2 is not held and unloaded
–75% may still remain in deoxygenated blood (reserve)
What other factors affect the affinity of hemoglobin for oxygen?
–Acidity
–PCO2
–Temperature
Acidity (Bohr Effect)
–As acidity increases (pH decreases), affinity of Hb for O2 decreases
–Increasing acidity enhances unloading
–Shifts curve to right
PCO2 (Haldane Effect)
–Also shifts curve to right
–As PCO2 rises, Hb unloads oxygen more easily
–Low blood pH can result from high PCO2
With limits as temperature increases….
•more oxygen is released from Hb
–During hypothermia, more oxygen remains bound
What is the function of 2,3-bisphosphoglycerate?
–BPG formed by red blood cells during glycolysis
–Helps unload oxygen by binding with Hb
Where will the curve shift with increased temperatures?
to the right
How much CO2 can readily dissolve in the blood?
7%
About 23% of the CO2 is transported how?
–Carbamino compounds
- combines with amino acids including those in Hb
- Carbaminohemoglobin
Bicarbonate ions: CO2 transport
- 70% transported in plasma as HCO3-
- Enzyme carbonic anhydrase forms carbonic acid (H2CO3) which dissociates into H+ and HCO3-
What are the respiratory structures in the brainstem?
–Medullary Rhythmicity Area
–Pontine (pneumotaxic) respiratory area
–Medullary Rhythmicity Area
- Dorsal groups stimulate the diaphragm
- Ventral groups stimulate the intercostal and abdominal muscles
–Pontine (pneumotaxic) respiratory area
•Involved with switching between inspiration and expiration
External Respiration: Carbon Dioxide
–Carbon dioxide diffuses from deoxygenated blood in pulmonary capillaries (PCO2 45 mmHg) into alveolar air (PCO2 40 mmHg)
–Continues until of PCO2 blood reaches 40 mmHg
Internal Respiration: Oxygen
–Oxygen diffuses from systemic capillary blood (PO2 100 mmHg) into tissue cells (PO2 40 mmHg) – cells constantly use oxygen to make ATP
–Blood drops to 40 mmHg by the time blood exits the systemic capillaries
Internal Respiration: Carbon Dioxide
–Carbon dioxide diffuses from tissue cells (PCO2 45 mmHg) into systemic capillaries (PCO2 40 mmHg) – cells constantly make carbon dioxide
–PCO2 blood reaches 45 mmHg
Internal Respiration: At rest…
•only about 25% of the available oxygen is used
–Deoxygenated blood would retain 75% of its oxygen capacity