BPK 305 - Lecture 23

3 paranasal sinuses

Frontal, sphenoid, maxillary

Respiratory tract organization

Pharyngeal tonsil, nasopharynx, uvula, oropharynx, epiglottis, laryngopharynx, esophagus

Lung lobes

Defined by fissures (3 on the right and 2 on the left)

bronchopulmonary segments

Basic anatomical units (each one gets air from different bronchus)

Defined by regions supplied by segmental bronchus

Can be surgically isolated

lobar bronchi

Supply each lobe

segmental bronchi

Numbered

Supply bronchopulmonary segments

conducting airways

Nose/mouth to non-respiratory bronchioles

Terminal bronchioles

Smallest bronchioles without alveoli

No cartilage

Respiratory unit

Basic physiological unit

Respiratory bronchioles

Alveolar ducts

Alveoli

Gas exchange function

O2 uptake and CO2 release

Conditioning inspired air

Warming and moisturizing

Filtering particles

Secretion of mucus

Clear debris from airways

What do lungs filter

Small emboli from the blood

What do lungs secrete

Surfactant and ACE

Acid base balance of blood

Using CO2/HCO3 to buffer (breath off or retain CO2)

Where is vocalization

Larynx

Olfaction

Nerve endings in roof of nose extend from olfactory epithelium to olfactory bulb

Does respiratory system help with heat loss

Yes

Air pump component

Upper airways /conducting airways

Lungs

Chest wall

Surface for gas exchange

Alveoli

Mechanism to carry O2 and CO2

Hemoglobin

Tissue diffusion

Capillary endothelium

Central mechanisms of ventilatory control

Chemoreceptors and drive to breath

Local/periphreal mechanisms to control ventilation

Chemoreceptors and hering-Breuer reflex

Circulatory system

Heart and vasculature

Bronchial tree

Conducting airways (bronchi, bronchioles- terminal), alveolar air spaces (bronchioles -respiratory, alveolar ducts and sacs)

Anatomical dead space

All conducting airways

Physiological dead space

From alveolar dead space (alveoli that are ventilated but not perfused)

Goblet cells

Secrete mucin, sialic acid and make mucus

Submucosal glands

Secrete water, ions, mucus, bacteriocidal lysozomye, lactoferrin and antileukoprotease

Sol layer

Periciliary payer of fluid produced by columnar epithelia and allows free movement of cilia (creates current to sweep mucus up)

Mucus layer

Traps airborne particles

Discontinuous blanket

Airway epithelium

Thins and becomes more permeable in alveoli and almost continuous with capillary membranes

Submucosal glands and goblet cells

Absent after 12th generation (bronchioles)

Cilia

200-250 per columnar epithelial cell

Contain ATPase throughout to mediate beating motion to sweep mucus out of airways

Mircrovilli

Brush cells, increase surface area

Air movement within airways

By convection (bulk flow) in conducting airways and by diffusion in alveolar airways

Alveolar airways facilitate diffusion

Huge surface area for gas exchange (80m), slow velocity of air

Alveolar pneumocytes type 1

Flat, elongated, 95% of alveolar surface, thin cytoplasm primary for gas exchange fused to endothelium

Alveolar pneumocytes type 2

Small, cuboidal, 2% of alveolus, synth surfactant, role in regeneration of type 1 cells

Alveolar pneumocytes type 3

Brush cells, found throughout lung, closely associated with nerves, possible role as chemoreceptors

Pores of Kohn and Canals of Lambert

Inter-alveolar pores and canals, allow gas diffusion between alveoli and bronchioles, prevent alveolar collapse due to surface tension, especially if an alveoli is congested

Pulmonary blood supply

Lungs get entire CO from the RV and gets 2 blood supplies

Pulmonary blood supply 1

Pulmonary artery carrying deoxygenated blood, pulmonary capillaries =5 um radius, 80m area, enhanced gas exchange , single file RBC passage, slow flow due to high CSA, 750ms transit time, very close to alveolus almost like a sheet of blood surrounding alveoli

Pulmonary blood supply 2

Larger airways receive dedicated bronchial arteries

Oxygenated blood supply to bronchioles, 1/3 drains to bronchial veins (RA) and 2/3 drains to pulmonary veins (LV)

Pulmonary arteries and arterioles

They are larger diameter and thinner than systemic circulation

Increases compliance so they can retain a large volumes of blood, reduce pulse pressure and their distensibility protects against oedema (more compliant because lower total resistance)

Pulmonary blood volume

10% (500ml) of total blood volume

Can decrease 50% or increase 200% (resting capillary blood volume is 75 max exercise is 200, increased CO increases pressure in pulmonary artery causing capillary recruitment)