Oxygenation pt 1

Question 1

Two major functions of the respiratory system

Answer 1

1 - supply the body with oxygen 2 - dispose of carbon dioxide

Question 2

The four processes of ventilation

Answer 2

1 - Pulmonary ventilation - the movement of air into and out of the lungs 2 - External respiration - O2 / CO2 exchange between the lungs and the blood 3 - Transport of respiratory gases - between the lungs and body tissues 4 - Internal respiration - O2 / CO2 exchange between the blood and tissue cells

Question 3

Gross structures of the respiratory system

Answer 3

• nostrils - nasal cavity - nasal sinuses - oral cavity - pharynx - larynx - trachea - bronchi - lungs

Question 4

Accessory structures

Answer 4

• soft palate - hard palate - glottis - epiglottis - diaphragm - intercostal muscles - plurae

Question 5

Functions of the nose

Answer 5

(only externally visible part of the respiratory system) - an airway for respiration - moistens and warms the air. Many capillaries line the nose. Their proximity is what warms the air. They also make nosebleeds common and profuse. - filters and cleans inspired air (hair and mucus trap substances) - resonating chamber for speech - houses olfactory receptors

Question 6

Gross structures of the nasal cavity

Answer 6

• olfactory nerves - conchae (protrusions. superior, middle and inferior) - meatus (dips. superior, middle and inferior) - hard palate - soft palate - uvula - tubal tonsil - nostrils - vibrissae - nasopharynx

Question 7

Functions of nasal cavity mucosa

Answer 7

• olfactory mucosa -contains smell receptors - Respiratory mucosa - contains sensory nasal glands which: -secrete mucus - secrete a watery fluid with antibacterial enzymes lysozyme and defensins - humidifies air - trigger the sneeze reflex to expel dust, pollen, etc.

Question 8

Structures of respiratory epithelium and their functions

Answer 8

• Cilia - hair-like projections that encourage mucus towards the pharynx to be swallowed - Goblet cells - produce mucus

Question 9

Functions of paranasal sinuses

Answer 9

• lighten the skull - may also aid in warming and moistening incoming air - if they get blocked, you can get severe headaches

Question 10

Name the specific paranasal sinuses

Answer 10

• Frontal sinuses (behind the eyes) - Ethmoid sinuses (between the eyes) - Sphenoid sinuses (between the eyes, below the ethmoid sinuses) - Maxillary sinuses (on either side of the nose)

Question 11

Areas of the pharynx

Answer 11

• nasopharynx - oropharynx - laryngopharynx

Question 12

Structure of the right lung and bronchus compared to the left

Answer 12

• The right lung has 3 lobes - The left only has 2. The left lung is slightly smaller than the right to make room for the heart, which is left-pointing. - The right bronchus is slightly wider and more vertical than the left. Any objects that enter the respiratory tract are more likely to become lodged in the right bronchus because of this.

Question 13

Describe the process and purpose of the Heimlich manoeuvre

Answer 13

• Used for when people are choking because of an obstructed trachea. - Press firmly in and up against their diaphragm, to force the air up and out of their lungs to ‘pop’ the obstruction out. - Not recommended by St Johns because of the risk of broken ribs.

Question 14

Describe ventilation-perfusion matching

Answer 14

ventilation = the amount of gas reaching the alveoli perfusion = the blood flow in the pulmonary capillaries. If there is greater ventilation than perfusion, the pulmonary arterioles dilate to increase blood flow to match. If there is greater perfusion, the pulmonary arterioles constrict to decrease blood flow to match. This creates the optimum gas exchange

Question 15

How does PCO2 in the blood encourage respiration?

Answer 15

• Carbon dioxide provides the most powerful stimulus to breathe - The regulation of breathing is a negative feedback mechanism - The body detects an increase in PCO2 in two ways: 1 - Central chemoreceptors in the medulla respond to H+ in CSF, which occurs from increased PCO2 in CSF. This accounts for 70% of the PCO2 response. 2 - Peripheral chemoreceptors in the carotid and aortic bodies detect increased levels of PCO2 in the blood. This accounts for 30% of the PCO2 response. - From there, afferent impulses travel to the medullary respiratory centres. - This sends efferent impulses to the respiratory muscles. - The respiratory muscles increase ventilation, leading to more CO2 exhaled. - This results in arterial PCO2 and pH to return to normal.

Question 16

What is surfactant, and what is its role in the alveoli?

Answer 16

Surfactant is a substance secreted by Alveolar Type II cells. It has a hydrophilic head and forked hydrophobic tail. It separates H2O molecules in the alveoli and prevents water surface tension, which would cause alveoli to collapse.

Question 17

What is lung compliance? What is it determined by and what diminishes it?

Answer 17

Lung compliance is the ease with which the lungs can be expanded. Determined by: - distensibility of the lung tissue and surrounding thoracic cage - surface tension of the alveoli Diminished by: - fibrosis (scar tissue) - blockage of respiratory passages with fluid or mucus - Reduced production of surfactant - Decreased flexibility of the thoracic cage or decreased ability of the thoracic cage to expand.

Question 18

What is dead space?

Answer 18

• air in the body that isn’t being used for gas exchange - anatomical dead space is the volume of air in the conducting passageways. This is ~150mls in a healthy adult. - alveolar dead space is air in the alveoli that cease to act in gas exchange due to damage or obstruction - total dead space is anatomical + alveolar dead space

Question 19

What are the three most common pulmonary function tests?

Answer 19

• Total ventilation - the total amount of gas in/out in a minute - forced vital capacity (VFC) - gas forcibly expelled after a deep breath - Forced expiratory volume (FEV) - amount expelled during specific time intervals of the FVC

Question 20

What are the conducting and respiratory zones?

Answer 20

Conducting zone - passages from the nose to the respiratory bronchioles. Cleans humidifies and warms inspired air. Respiratory zone - the site of gas exchange - bronchioles, alveolar ducts and alveoli.

Question 21

Functions of the larynx

Answer 21

• provides a patent (open) airway - acts as a switching passageway for food and air into proper channels. - voice production

Question 22

Function and structure of the epiglottis

Answer 22

• made of elastic cartilage - when tilted up, the larynx is open to the trachea for incoming/outgoing air. - when swallowing, the epiglottis tilts down, closing the larynx and preventing food/fluids from entering the trachea

Question 23

What are the two types of circulation in the lungs?

Answer 23

Pulmonary circulation - deoxygenated blood from the heart into the lungs. Oxygenated blood from the lungs to the heart. Bronchial circulation - provides oxygenated blood to the lung tissue via the bronchial arteries. Most blood from the bronchial circulation returns to the heart via the pulmonary veins.

Question 24

How are lungs innervated?

Answer 24

• parasympathetic motor fibres- cause air tubes to constrict - sympathetic motor fibres- causes air tubes to dilate - visceral sensory fibres - responsible for the cough reflex, etc

Question 25

What is the function of the plurae, and describe some illnesses related to them.

Answer 25

Plurae separate the heart and the two lungs limiting the spread of local infections. Pleurisy is inflammation of the plurae. Causes friction and pain, also increased fluid which can inhibit breathing. Pleural effusion - fluid accumulation (including blood) in the pleural cavity. Pneumothorax - air in the pleural cavity.

Question 26

Describe the different respiratory pressures

Answer 26

Volume changes cause pressure changes, which cause air to move. Respiratory pressure is always described relative to atmospheric pressure (the pressure exerted by gases surrounding the body. At sea level, 1 atmospheric unit = 760 mmHg). Eg, a respiratory pressure of -4 mmHg = 756mmHg because its 4 less than atmospheric pressure. Intrapulmonary pressure (Ppul) = pressure in the alveoli. Rises and falls with breathing but always equalises with atmospheric pressure eventally. Intrapleural pressure (Pip) = pressure in the pleural cavity. Also rises and falls with breathing but is always about 4mmHg less than pulmonary pressure. Transpulmonary pressure = Ppul-Pip = the pressure that keeps the air spaces in the lungs/keeps the lungs from collapsing.

Question 27

What is atelectasis?

Answer 27

Lung collapse. Will happen if Pip = 1atm or Ppul. Can be caused by pneumonia or air in the pleural cavity (pneumothorax)

Question 28

What is Boyle’s law?

Answer 28

Gas pressure varies inversely with it’s volume. As volume goes up, pressure goes down and vice versa

Question 29

How do volume, Ppul and Pip change during breathing?

Answer 29

On inspiration: - volume increases from 0 to ~0.5L - Ppul drops from 0 to ~ -1mmHg - Pip drops from -4mmHg to ~-6mmHg On expiration: - Ppul goes to +1mmHg then returns to 0 - Pip returns to -4mmHg

Question 30

What are quiet respiration, forced respiration and non-respiratory air movements?

Answer 30

Quiet respiration = unconscious, steady breathing. Relies on lung elasticity. Forced inspiration = accessory muscles increase volume - scalenes, sternocleido-mastoid muscles, pectoralis minor. Forced expiration = oblique and transverse muscles. Non-respiratory air movements = coughing, sneezing, crying, laughing, hiccuping, yawning

Question 31

What are respiratory volumes?

Answer 31

Tidal volume (TV) - volume of air incoming and outgoing in 1 quiet breath. Inspiratory reserve volume (IRV) - volume of air incoming in 1 forced inhalation. Expiratory reserve volume (ERV) - volume of air that can be forcibly expired after normal exhalation Residual volume (RV) - volume of air that remains in the lungs after exhalation to keep alveoli open and prevent lung collapse.

Question 32

What are respiratory capacities?

Answer 32

Inspiratory capacity (IC) - total amount of air that can be inspired (TV+IRV) Functional residual capacity (FRC) - amount of air remaining in the lungs after normal tidal volume expiration (RV+ERV) Vital capacity (VC) - total volume of exchangable air (TV+IRV+ERV) Total lung capacity (TLC) - (TV+IRV+ERV+RV)

Question 33

What is Dalton’s Law of Partial Pressures?

Answer 33

the total pressure exerted by a mixture of gases is the sum of the pressures exerted independantly by each gas.

Question 34

What is Henry’s Law?

Answer 34

when a gas comes in contact with a liquid, the gas will dissolve in the liquid in proportion to its partial pressure.

Question 35

What respiratory centres are there in the brain?

Answer 35

In the medulla - the ventral respiratory group (VRG) extend from the spinal cord to the pons-medulla junction. This is the respiration rhythm-generating area. - the dorsal respiratory group (DRG) is located dorsally near the root of cranial nerve IX. In the Pons - Pontine respiratory centres influence and modify the activity of the medullary neurons. Responsible for smoothing the transition from inspiration to expiration and vice versa.

Question 36

What is COPD?

Answer 36

Chronic Pulmonary Obstructive Diseases. - includes emphysema anc chronic bronchitis - chronic, irreversible decrease in the ability to force air out of the lungs. - causes frequent coughing and pulmonary infections. - can lead to hypoventilation, respiratory acidosis and hypoxemia. - COPDs are treated with inhaled bronchodilators and corticosteroids. If severe dyspnea and hypoxia are present, oxygen use is necessary.

Question 37

What is emphysema?

Answer 37

• A COPD. - permanent enlargement of the alveoli and destruction of the alveolar walls. - mostly caused by smoking but is sometimes genetic.

Question 38

What is Chronic Bronchitis?

Answer 38

• A COPD - inhaled irritants cause excess mucus, causing mucosae to become inflamed and fibrous. Causes airway obstruction and impairs lung function. Frequent pulmonary infections - Often caused by smoking and/or pollution

Question 39

What is asthma?

Answer 39

• coughing, dyspnea, wheezing, chest tightness. - not a COPD because there are periods of no symptoms. It is not always chronic and it can be reversed. - The most common form of asthma is allergic asthma, caused by inflammation of the airways. - asthma is more common in children than adults. - treated with inhaled bronchodilators and corticosteroids, which have greatly decreased the number of asthma related deaths.

Question 40

What is Tuberculosis (TB)?

Answer 40

• an infectious disease, caused by the bacterium Mycobacterium tuberculosis. - 1/3 of the world’s population has tuberculosis, but in the majority of people, with healthy immune systems, it is contained in small nodules in the lungs. - if an active infection, symptoms are fever, night sweats, weight loss, racking cough, coughing up blood. - treated with antibiotics, but facing a large problem with antibiotic resistant strains.

Question 41

What is lung cancer?

Answer 41

• leading cause of cancer death in North America. - 90% of cases are caused by smoking. - mosst people die within a year of diagnosis. - most common forms are: - adenocarcinoma - squamous cellcarcinoma - small cell carcinoma

Question 42

What is the bronchial tree?

Answer 42

the passageway from the larynx to the alvioli. Trachea to bronchus to primary bronchus to secondary bronchus to tertiary bronchus to bronchioles to alveolar ducts to avleoli.