Bio 226 Respiratory Lec

Respiratory system

supplies body with O2 for cellular respiration and dispose of CO2 (waste product of cellular respiration)

What system is closely coupled with the respiratory system?

circulatory system

What 4 processes are involved in respiration?

pulmonary ventilation (breathing), external respiration, internal respiration, and transportation of gases

What 2 processes does the respiratory system oversee?

pulmonary ventilation (breathing) and external respiration

What 2 processes does the circulatory system oversee?

transportation of gases and internal respiration

Pulmonary ventilation

breathing; movement of air into and out of lungs

External respiration

exchange of O2 and CO2 between lungs and blood; moves air out of the lungs

Transportation of gases

exchange of O2 and CO2 gases in blood

Internal respiration

exchange of O2 and CO2 between systemic blood vessels and tissues; moves air into the lungs

What is oxygen used for?

O2 is used for metabolism which produces energy

What is the concentration gradient of air flow?

From higher concentration of air to lower concentration of air

Nose (external nose and nasal cavity) function

Produces mucus to filter, warm, and moistens air

Paranasal sinuses function

Warms, moistens, and filters incoming air

Pharynx function

Passageway for air and food and facilitates exposure of immune system

Larynx function

Air passageway; prevents food from entering respiratory tract

Trachea function

Voice production and air passageway

Bronchial tree function

Cleans, warms,and moistens incoming air

Alveoli function

Site of gas exchange

Lung function

Houses respiratory passages

Pleurae function

Produces lubricating fluid

Sphincter function of larynx

Vocal folds may act as a sphincter to prevent air passage (ex. Valsalva’s maneuver)

Valsalva’s maneuver

Glottis closes to prevent exhalation, muscles will contract, abdominal pressure rises…to help empty rectum or stabilize trunk during heavy lifting.

Trachea

Windpipe; extends from larynx into mediastinum, where it divides into two main bronchi

How many layers is the trachea made up of?

3; mucosa, submucosa, and adventitia (includes hyaline cartilage, trachea lips, and carina)

Mucosa

Ciliated pseudostratified epithelium with goblet cells

Submucosa

Connective tissue with zero mucous glands supported by 16-20 C-shaped cartilage rings

C-shaped cartilage rings

Prevents collapse of trachea

Adventitia

Outermost layer made of connective tissue

Trachealis

Smooth muscle fibers; contracts during coughing to expel mucus

Carina

Last tracheal cartilage that branches into two main bronchitis; mucosa is highly sensitive

Violent coughing will be triggered if any foreign object makes contact with this structure

Bronchial tree

Air passages undergoing 23orders of branching

What structures give rise to respiratory zone structures?

Conducting zone structures

Conducting zone structures

Trachea > R/L Primary (main) bronchi > R/L Secondary (lobar) bronchi > R/L Tertiary (segmental) bronchi > bronchioles (less than 1 mm diameter) > terminal bronchioles (less than 0.5 mm diameter)

What change occurs during the transfer of air from bronchi to bronchioles?

Support structures change:

Cartilage rings become irregular plates

In bronchioles, elastic fibers replace cartilage

Respiratory zone structures

Respiratory bronchioles > alveolar ducts > alveolar sacs (saccules) > alveoli (last stop before gas exchange)

Respiratory membrane

Blood air barrier consisting of alveolar and capillary walls that fuse basement membranes (thin~0.5 ųm); allows for gas exchange by simple diffusion

What do alveolar walls consist of?

Type I alveolar cells (simple squamous epithelium-gas exchange) and Type II alveolar cells (cuboidal epithelium)

Type II alveolar cells function

Secrete surfactant and anti microbial proteins (pneumocyte)

What structures are alveoli surrounded by?

Fine elastic fibers and pulmonary capillaries to keep structures intact

Alveolar pores

Connects adjacent alveoli to equalize air pressure throughout lungs (provides alternout routes in case of blockage)

Alveolar macrophages (dust cells)

Keeps alveolar surfaces sterile in case of pathogens being swallowed/breathed in

2 million dead pathogens/hour are carried by cilia to throat and swallowed

Pleurae

Thin, double-layered serosal membrane; divides thoracic cavity into two pleural cavity into two pleural compartments and mediastinum

Parietal pleura

Membrane on thoracic wall, superior face of diaphragm, around heart, and between lungs (closest to other structures)

Visceral pleura

Membrane on internal lung surface (closest membrane to lung/organ)

Pleural fluid

(Fill slit-like pleural cavity between two pleurae) lubrication and surface tension that assists in expansion and recoil of lungs

Inspiration

Gases flow into lungs

Expiration

Gases exit lungs

Atmospheric pressure (Patm)

Enough air pressure present to push air into lungs; 0 mm Hg (760 mm Hg)

Trans pulmonary pressure

4 mm Hg (difference b/t 0 & -4); pressure transferring from blood to lungs

Intrapleural pressure (Pip)

-4 mm Hg (756 mm Hg); pressure b/t visceral & parietal pleura (pulls lungs open to expand to breathe easier)

Intrapulmonary pressure (Ppul)

Pressure within lungs; 0 mm Hg (760 mm Hg)

Pulmonary Ventilation

Consists of inspiration and expiration

Boyle’s law

Relationship between pressure + volume of a gas; if amount of gas is the same and container size is reduced, pressure will increase

Pressure inside of lungs is low, air can flow in (inhale) when lungs are filled w/ air (^ vol), air pressure outside lungs lowers (exhale)

Inspiration in pulmonary ventilation

active process involving inspiratory muscles

Action of the diaphragm

contracts downward and flattens out which increases thoracic volume (inhalation)

Action of intercostal muscles

rib cage is lifted up and out which increases thoracic volume (inhalation)

When can forced/deep inspiration occur?

during vigorous exercise or in people with COPD (chronic obstructive pulmonary disease)

Activated accessory muscles are also known as

scalenes, sternocleidomastoid, and pectoralis minor (erector spinae muscles of back also help to straighten thoracic curvature)

What is the function of activated accessory muscles?

further increase thoracic cage size, creating a larger pressure gradient so more air is drawn in

Passive process

also known as quiet expiration

Forced expiration

active process that uses oblique + transverse abdominal muscles

Three factors that influence the ease of air passage + amount of energy required for breathing:

airway resistance, alveolar surface tension, lung compliance

Airway resistance

major nonelastic source of resistance to gas flow; occurs in airways which in turn drives gas movement

Alveolar surface tension

the attraction of liquid molecules to one another at a gas-liquid interface which tends to cause alveoli to shrink (collapse)

Surfactant

body’s detergent-like lipid and protein complex that helps reduce surface tension of alveolar fluid (prevents collapse + produces type II cells)

Lung compliance

measure of change in lung volume given change in transpulmonary pressure (stretch of lung)

Why is lung compliance normally high?

the ability of lung tissue stretch

surfactant

easier to expand lungs

-diminished by aging

Respiratory volume

assesses respiratory status

Respiratory capacities

the combination of respiratory volumes to give insight on a person’s ability to transfer O2 into tissues

Anatomical dead space

consists of air that remains in passageways

Alveolar dead space

space occupied by non functional alveoli (due to collapse)

Total dead space

sum of anatomical and alveolar dead space

Spirometry can distinguish between:

obstructive pulmonary disease and restrictive disease

Obstructive pulmonary disease (COPD)

increased airway resistance (bronchitis)

Restrictive disease

reduced TLC due to disease or exposure to environmental agents (firbrosis)

Pulmonary functions tests

measure rate of gas movement

Forced vital capacity (FVC)

amount of has forcibly expelled after deep breath

Forced expiratory volume (FEV)

amount of gas expelled during time interval of FVC

FEV1

is the amount of air expelled in the 1st second

External respiration

diffusion of gases between blood and lungs

outside of body>lungs>blood

Internal respiration

diffusion of gases between blood and tissues

inside of body>blood>tissues

External and Internal respiration are subject to what processes?

basic properties of gases and composition of alveolar gas

Pulmonary gas exchange

involves exchange of O2 and CO2 across respiratory membranes

Exchange of O2 and CO2 is influenced by:

Ppg and has solubilities

thickness and surface area of membrane

ventilation-perfusion coupling

Ventilation-perfusion coupling

matching of alveolar ventilation with pulmonary blood perfusion

What form of respiration involved capillary gas exchange in body tissues?

internal respiration

Tissue PO2

lower partial pressure than in arterial blood, so O2 moves from blood to tissues

Tissue PCO2

higher partial pressure than in arterial blood, so CO2 moves from tissues into blood

Venous blood return pressure

PO2 = 40 mm Hg

PCO2 = 45 mm Hg

Partial pressure gradients promoting gas movements in the body

Factors that influence hemoglobin saturation:

PO2 + PCO2; partial pressure of O2/CO2 (^ pressure = ^ saturation)

Temperature (heat)

Blood pH

Concentration of BPG (bisphosphoglycerate)

Where is BPG produced?

during glycolysis by RBCs; when BPG levels ^ then O2 levels decrease

What happens when cells metabolize glucose?

the use of O2 increases in PCO2 and H+ in capillary blood

declines blood pH (acidosis)

increases PCO2 causing hemoglobin+O2 bond to weaken (Bohr effect)

O2 unloading occurs

What decreases hemoglobin affinity for O2?

heat production during movement

Hemoglobin-oxygen dissociation curve

percentage of Hb saturation with O2 at any partial pressure of oxygen

What influences the dissociation curve?

pH, CO2, Exercise, Temperature (effect how well O2 comes off Hb)

PO2 (lungs)

100 mm Hg (about 100% saturation)

PO2 (tissues at rest)

40 mm Hg (about 75% saturation)

PO2 (tissues during exercise)

15 mm Hg (about 25% saturation)

How is CO2 transported in the blood?

by being dissolved in plasma, bound to Hb, or as HCO₃ ions (buffers to control pH-70%)