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respiratory Flashcards

1
Q

Structurally
❑ Upper respiratory system
◼ Nose, pharynx and associated structures
❑ Lower respiratory system
◼ Larynx, trachea, bronchi and lungs
Functionally
❑ Conducting zone – conducts air to lungs
◼ Nose, pharynx, larynx, trachea, bronchi, bronchioles and terminal bronchioles
❑ Respiratory zone – main site of gas exchange
◼ Respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli

A

Respiratory System Anatomy

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2
Q

External nose – portion visible on face
❑ Internal nose – large cavity beyond nasal vestibule
❑ Internal nares or choanae
❑ Ducts from paranasal sinuses and nasolacrimal ducts open into internal nose

A

Nose

◼ Nasal cavity divided by nasal septum
◼ Nasal conchae subdivide cavity into meatuses
❑ Increase surface are and prevents dehydration
◼ Olfactory receptors in olfactory epithelium

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3
Q

❑ Starts at internal nares and extends to cricoid cartilage of
larynx
❑ Contraction of skeletal muscles assists in deglutition

❑ Functions
◼ Passageway for air and food
◼ Resonating chamber
◼ Houses tonsils

A

Pharynx

❑ 3 anatomical regions
◼ Nasopharynx
◼ Oropharynx
◼ Laryngopharynx

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4
Q

Short passageway connecting laryngopharynx with trachea
❑ Composed of 9 pieces of cartilage

◼ Thyroid cartilage or Adam’s apple
◼ Cricoid cartilage hallmark for tracheotomy
❑ Epiglottis closes off glottis during swallowing
❑ Glottis – pair of folds of mucous membranes, vocal folds(true vocal cords, and rima glottidis (space)
❑ Cilia in upper respiratory tract move mucous and trapped
particles down toward pharynx
❑ Cilia in lower respiratory tract move them up toward
pharynx

A

Larynx

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5
Q

❑ Function in holding breath against pressure in thoracic

cavity

A

Ventricular folds (false vocal cords) – superior pair

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6
Q

Muscle contraction pulls elastic ligaments which stretch
vocal folds out into airway
❑ Vibrate and produce sound with air
❑ Folds can move apart or together, elongate or shorten,
tighter or looser

A

Vocal folds (true vocal cords) – inferior pair

Androgens make folds thicker and longer – slower
vibration and lower pitch

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7
Q

Extends from larynx to superior border of T5
◼ Divides into right and left primary bronchi
❑ 4 layers
◼ Mucosa
◼ Submucosa
◼ Hyaline cartilage
◼ Adventitia
❑ 16-20 C-shaped rings of hyaline cartilage
◼ Open part faces esophagus

A

Trachea

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8
Q

❑ Right and left primary bronchus goes to right lung
❑ Carina – internal ridge
◼ Most sensitive area for triggering cough reflex
❑ Divide to form bronchial tree
◼ Secondary lobar bronchi (one for each lobe), tertiary
(segmental) bronchi, bronchioles, terminal bronchioles

A

Bronchi

❑ Structural changes with branching
◼ Mucous membrane changes
◼ Incomplete rings become plates and then disappear
◼ As cartilage decreases, smooth muscle increases

❑ Sympathetic ANS – relaxation/ dilation
❑ Parasympathetic ANS – contraction/ constriction

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9
Q

Separated from each other by the heart and other
structures in the mediastinum
❑ Each lung enclosed by double-layered pleural membrane
◼ Parietal pleura – lines wall of thoracic cavity
◼ Visceral pleura – covers lungs themselves
❑ Pleural cavity is space between layers
◼ Pleural fluid reduces friction, produces surface tension (stick
together)
◼ Cardiac notch – heart makes left lung 10% smaller
than right

A

Lungs

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10
Q

Lobes – each lung divides by 1 or 2 fissures
❑ Each lobe receives it own secondary (lobar) bronchus that branch into tertiary (segmental) bronchi
◼ Lobules wrapped in elastic connective tissue and contains a lymphatic vessel, arteriole, venule and
branch from terminal bronchiole

◼ Terminal bronchioles branch into respiratory
bronchioles which divide into alveolar ducts
◼ About 25 orders of branching

A

Anatomy of Lungs

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11
Q

Cup-shaped outpouching
❑ Alveolar sac – 2 or more alveoli sharing a
common opening

A

Alveoli

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12
Q

❑ 2 types of alveolar epithelial cells

A

◼ Type I alveolar cells – form nearly continuous lining,
more numerous than type II, main site of gas exchange

◼ Type II alveolar cells (septal cells) – free surfaces
contain microvilli, secrete alveolar fluid (surfactant
reduces tendency to collapse)

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13
Q

❑ Alveolar wall – type I and type II alveolar cells
❑ Epithelial basement membrane
❑ Capillary basement membrane
❑ Capillary endothelium
❑ Very thin – only 0.5 µm thick to allow rapid diffusion of gases

A

Respiratory membrane

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14
Q

Lungs receive blood from

A

❑ Pulmonary artery - deoxygenated blood
❑ Bronchial arteries – oxygenated blood to perfuse muscular
walls of bronchi and bronchioles

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15
Q

◼ Respiration (gas exchange) steps

A
  1. Pulmonary ventilation/ breathing
    ◼ Inhalation and exhalation
    ◼ Exchange of air between atmosphere and alveoli
  2. External (pulmonary) respiration
    ◼ Exchange of gases between alveoli and blood
  3. Internal (tissue) respiration
    ◼ Exchange of gases between systemic capillaries and
    tissue cells
    ◼ Supplies cellular respiration (makes ATP)
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16
Q

Pressure inside alveoli lust become lower than
atmospheric pressure for air to flow into lungs
◼ 760 millimeters of mercury (mmHg) or 1
atmosphere (1 atm)
❑ Achieved by increasing size of lungs
◼ Boyle’s Law – pressure of a gas in a closed
container is inversely proportional to the volume of
the container
❑ Inhalation – lungs must expand, increasing lung
volume, decreasing pressure below atmospheric
pressure

A

Inhalation/ inspiration

17
Q

Inhalation is active Contraction of
❑ 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
❑ Accessory muscles for deep, forceful inhalation

A

Inhalation
◼ When 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

18
Q

Pressure in lungs greater than atmospheric pressure
❑ Normally passive – muscle relax instead of contract
◼ Based on elastic recoil of chest wall and lungs from elastic
fibers and surface tension of alveolar fluid
◼ Diaphragm relaxes and become dome shaped
◼ External intercostals relax and ribs drop down
❑ Exhalation only active during forceful breathing

A

Exhalation/ expiration

19
Q

◼ Air pressure differences drive airflow

◼ 3 other factors affect rate of airflow and ease of
pulmonary ventilation
1. Surface tension of alveolar fluid
-Causes alveoli to assume smallest possible diameter
- Accounts for 2/3 of lung elastic recoil
-Prevents collapse of alveoli at exhalation
2. Lung compliance
◼ High compliance means lungs and chest wall expand easily
◼ Related to elasticity and surface tension
3. Airway resistance
◼ Larger diameter airway has less resistance
◼ Regulated by diameter of bronchioles & smooth muscle tone

A

Airflow

20
Q

Lung volumes and capacities

A

Minute ventilation (MV) = total volume of air
inhaled and exhaled each minute
◼ Normal healthy adult averages 12 breaths
per minute
◼ moving about 500 ml of air in and out of lungs
(tidal volume)
◼ MV = 12 breaths/min x 500 ml/ breath
= 6 liters/ min

21
Q

Lung Volumes

Total lung capacity = vital capacity + residual
volume

A

Only about 70% of tidal volume reaches respiratory
zone
◼ Other 30% remains in conducting zone
◼ Anatomic (respiratory) dead space – conducting
airways with air that does not undergo respiratory
gas exchange
◼ Alveolar ventilation rate – volume of air per minute
that actually reaches respiratory zone
◼ Inspiratory reserve volume – taking a very deep
breath

22
Q

inhale normally

and exhale forcefully

A

◼ Expiratory reserve volume

23
Q

air remaining after

expiratory reserve volume exhaled

A

Residual volume

24
Q

inspiratory reserve volume +

tidal volume + expiratory reserve volume

A

Vital capacity

25
Q

❑ 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
❑ Each gas diffuses across a permeable membrane
from the are 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

A

Dalton’s Law

Exchange of Oxygen and Carbon Dioxide

26
Q

❑ Quantity of a gas that will dissolve in a liquid is
proportional to the partial pressures of the gas and its solubility
❑ Higher partial pressure of a gas over a liquid and
higher solubility, more of the gas will stay in solution
❑ Much more CO2
is dissolved in blood than O2 because CO2 is 24 times more soluble
❑ Even though the air we breathe is mostly N2 , very little dissolves in blood due to low solubility
◼ Decompression sickness (bends)

A

Henry’s law

27
Q

External Respiration in Lungs

A

❑ 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
❑ Small amount of mixing with blood from conducting portion of respiratory system drops PO2 of blood in pulmonary veins to 100mmHg

◼ 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

28
Q

Internal Respiration

A

Internal respiration – in tissues throughout body
◼ 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
◼ 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
◼ At rest, only about 25% of the available oxygen is used
❑ Deoxygenated blood would retain 75% of its oxygen capacity

29
Q

Rate of Pulmonary and Systemic Gas Exchange

A

◼ Depends on
❑ Partial pressures of gases
◼ Alveolar PO2 must be higher than blood PO2 for diffusion to occur – problem with increasing altitude
❑ Surface area available for gas exchange
❑ Diffusion distance
❑ Molecular weight and solubility of gases

◼ 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

30
Q

❑ Only about 1.5% dissolved in plasma
❑ 98.5% bound to hemoglobin in red blood cells
◼ Heme portion of hemoglobin contains 4 iron atoms –each can bind one O2 molecule
◼ Oxyhemoglobin
◼ Only dissolved portion can diffuse out of blood into cells
◼ Oxygen must be able to bind and dissociate from heme

A

Oxygen transport

31
Q

Relationship between Hemoglobin and

Oxygen Partial Pressure

A

Higher the PO2, More O2 combines with Hb
❑ Fully saturated – completely converted to oxyhemoglobin
❑ Percent saturation expresses average saturation of hemoglobin 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)

32
Q

Other factors affecting affinity of Hemoglobin

for oxygen

A 
◼ Each makes sense if you keep in mind that metabolically active tissues need O2 and
produce acids, CO2  and heat as wastes
❑ Acidity
❑ PCO2
❑ Temperature
33
Q

Bohr Effect

A 
❑ As acidity increases (pH
decreases), affinity of Hb
for O2 decreases
❑ Increasing acidity
enhances unloading
❑ Shifts curve to right
◼ PCO2
❑ Also shifts curve to right
❑ As PCO2 rises, Hb unloads
oxygen more easily
❑ Low blood pH can result
from high PCO2
34
Q

Temperature Changes

A 
❑ Within limits, as
temperature increases, more
oxygen is released from Hb
❑ During hypothermia,
more oxygen remains bound
◼ 2,3-bisphosphoglycerate
❑ BPG formed by red
blood cells during glycolysis
❑ Helps unload oxygen
by binding with Hb
35
Q

Fetal and Maternal Hemoglobin

A

◼ Fetal hemoglobin has a
higher affinity for oxygen than adult hemoglobin
◼ Hb-F can carry up to
30% more oxygen
◼ Maternal blood’s oxygen readily transferred to fetal
blood

36
Q

Carbon Dioxide Transport

A

❑ Dissolved CO2
◼ Smallest amount, about 7%

❑ Carbamino compounds
◼ About 23% combines with amino acids including those in Hb
◼ Carbaminohemoglobin

❑ Bicarbonate ions
◼ 70% transported in plasma as HCO3-
◼ Enzyme carbonic anhydrase forms carbonic acid (H2CO3)
which dissociates into H+ and HCO3

37
Q

❑ HCO3
- accumulates inside RBCs as they pick up carbon dioxide
❑ Some diffuses out into plasma
❑ To balance the loss of negative ions, chloride (Cl-)
moves into RBCs from plasma

❑ Reverse happens in lungs – Cl- moves out as moves back into RBCs

A

◼ Chloride shift

CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3

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