Part 2 5 categories

What is Lung Elasticity?

Ability to return to resting shape after stretched or compressed

What 2 main structures that are highly elastic?

Lungs and Chest Wall

Explain Elastic Recoil (3)

• The tendency of lungs is to recoil in and collapse

• The chest wall wants to spring outward

• The two forces counterbalance each other, unless interrupted (i.e. PTX)

What is Lung Compliance?

The ease w which the lungs expand or the chest wall stretches during inhalation

What greatly enhances lung compliance?

Surfactant (Lower Surface Tension = Easier Expansion)

Lung Compliance is assisted by what?

Elastic forces of chest wall if unopposed by elastic recoil of lungs

Principal Muscles of Respiration: Inspiration (2)

Diaphragm and External Intercostal

Accessory Muscles of Respiration: Inspiration (6)

• SCM

• Scalenes

• Pec Major and Minor

• Serratus Anterior

• Upper Trap

• Lats

Expiration is a _____ process

Passive

Muscles of Respiration: Active Expiration (5)

• Internal Intercostals

• Rectus Abdominis

• Internal/External Obliques

• Transvers Abdominis

• QL

What is Quiet Breathing?

Passive process resulting from elastic recoil of the lungs, rib cage, and diaphragm

Mechanics of Respiration: Inspiration

Active contraction of diaphragm and external intercostal muscles results in thoracic and lung expansion

What causes air to flow into lungs and inflates lungs during inspiration

Negative intrapleural pressure and falling alveolar pressure

Mechanics of Respiration: Active Breathing during Expriation

Contraction of expiratory muscles forces air OUT of the lungs faster and more forcefully

Mechanics of Respiration: Quiet Breathing during Expiration (3)

• Passive relaxation of inspiratory muscles to resting position

• Elastic recoil of lungs causes alveolar pressure to rise

• Air flows out of lungs

What is Total Lung Capacity?

Volume of air in the lungs after MAXIMAL INHALATION

Total Lung Capacity amount in adult males?

~ 6L in normal adult male

What is Vital Capacity (VC)?

Air that can be EXCHANGED by the lungs during a MAXIMAL INHALATION AND EXHALATION

What is Residual Volume?

Air always present in the lungs

How much % of Residual Volume is of Total Lung Capacity?

~ 20%

Why do we need Residual Volume (Dead Space)?

To keep lung inflated

What is Tidal Volume (TV)?

Air exchanged during NORMAL BREATHING

How many ml per breath is Tidal Volume?

~ 500 ml

Where does the movement of gasses in and out of blood occur?

Alveolar-Capillary Membrane <<

• O2 from alveolar air into blood

• CO2 from blood into alveolar air

• From high to low concentration

What is Diffusion affected by? (4)

• Concentration and solubility of gases

• Membrane thickness

• Surface area

• Pathology >> fibrosis, fluid, edema

Is breathing voluntary of involuntary?

Involuntary

Central chemoreceptors respond to changes in acidity of what?

Brain extracellular fluid

What increased ion concentration stimulates ventilation?

Increase in H = acidosis

What do input from peripheral chemoreceptors respond to?

Changes in CO2, H, Partial Pressure of o2

Increase in what stimulates ventilation?

Arterial CO2 and pH OR PaO2 < 60 mmHg

What receptors affect breathing? (2)

• Alveolar stretch receptors

• Proprioceptors in joint and muscles

What is the purpose of Alveolar Stretch Receptors?

Tell brain how inflated lungs are to alleviate over inflation

Other 5 inputs affecting breathing?

• Emotional input via the limbic system

• Temperature

• Medication

• Anesthesia

• Disease

What is Ventilation a process of?

Cyclic processes of inhalation and exhalation <<

• Moving air in and out of lungs <<

What does Minute Ventilation (VE) equal?

Amount of air moved into and out of lungs per min

VE equals what?

TV x RR

Minute Volume (V) equal what?

Alveolar Volume + Dead Space Ventilation (V = VA + VD)

What is normal Minute Ventilation?

• 5-10 L/min at REST

• 15-20x during EXERCISE

At sea level, atmospheric air is what?

• ~ 21% O2

• 79% N

What fraction decreases at higher elevations?

Fraction of Inspired Oxygen (FiO2)

What can poor air quality cause in ventilation? (5)

• Acute/chronic lung irritation

• Lung damage

• Allergies

• Inflammatory reactions

• Thickening of alveolar membranes

What is perfusion (Q)?

• Blood flow into capillary beds

• Blood flow through pulmonary circulation that is available for gas exchange

What fields perfused greater in a dependent lung?

Base > Apex

What is a Dependent Lung?

Which ever part of the lung is dependent/influenced by gravity due to blood pooling

What is the Ventilation/Perfusion Ratio (V/Q)?

Ratio of air flow and blood flow to the alveolus, lung region, or entire lung

Normal V/Q?

0.8

V/Q: When does optimal gas exchange occur?

When blood flow through the capillary is in equal proportion to the ventilation in and out of alveoli <<

• V/Q = 1

Where does V/Q ratio optimal gas exchange occur?

Midzone of upright lungs

Positional Dirstibution is dependent on what?

Portions of the lungs which receive better ventilation

Distribution of Gasses Characteristics (2)

• Weight of lung pulls and stretches top, increasing resistance to further expansion (already relatively expanded)

• Pressure near bottom is less negative, inspired air preferentially goes to dependent region

Smaller resting volume = what

Large change in volume

Pulmonary Plexus is formed by what?

Branches of the sympathetic trunk and vagus nerve

What is Sympathetic Stim?

Adrenergic <<

• Bronchodilation

• Slight Vasoconstriction

• Inhibition of Glandular Secretion

What is Parasympathetic Stim?

Cholinergic <<

• Bronchoconstriction

• Indirect Vasodilation

• Glandular Secretion

What are the 3 Key Categories of Cardiac Dysfunction?

• Myocardial Pump Dysfunction

• Myocardial Vascular Dysfunction

• Peripheral Vascular Dysfunction

Myocardial Pump Dysfunction Examples (4)

• Valve Disease

• Arrhythmias

• Cardiomyopathy

• Heart Failure

Myocardial Vascular Dysfunction Examples (4)

• CAD

• MI

• Angina

• Acute Coronary Syndrome

Peripheral Vascular Dysfunction Examples (3)

• PAD

• Venous Insufficiency

• DVT

Basic Functions of Cardiovascular System (6)

• Circulation of blood

• Delivery of oxygen, nutrients, and water

• Circulation of hormones

• Temperature regulation

• Removal of metabolites

• Maintenance of acid-base balance (pH)

General Heart Anatomy

• Size: fist

• Shape: pyramid cone

• Function: 2 separate pumps

Location of Heart

Location: mediastinum <<

• Left side: 2nd costal cartilage - 5th intercostal space

• Right side: 3rd - 6th intercostal space

Heart Anatomy: Atria (4)

• Reservoir for ventricle

• Elastic, to handle increased venous return

• Small contribution at rest

• Increases with exercise

Heart Anatomy: Ventricles (2)

• Primary Pump

• R/L Venticles have equal volume (~ 120 mL)

Which ventricle is larger?

L has larger muscle mass due to higher systemic resistance

AV Valved during Cardiac Cycle: Systole

• Contraction Phase

• Valves Closed

AV Valved during Cardiac Cycle: Diastole

• Relaxation Phase

• Valves Open