Unit 3 Pathophysiology - Chapter 35 Structure and fx of pulmonary system

Question 1

Pulmonary system consists of

Answer 1

two lungs, upper and lower airway
* chest wall (skin, fat, muscles, bones, and other tissues that form a protective sturcture around vital organs in the area between the neck and the abdomen
* diaphragm (this thin, dome-shaped muscle sits below your lungs and heart. It’s attached to your sternum (a bone in the middle of your chest), the bottom of your rib cage and your spine.
* pulmonary and bronchial circulations

Question 2

What is the conducting airway pathway?

Answer 2

Nasopharynx, oropharynx, trachea, bronchi, and brochioles to the 16th division (and reverse)

Question 3

Gas exchange occurs where?

Answer 3

beyond the sixteenth division
* respiratory bronchioles
* alveolar ducts
* and alveoli
* all together => acinus (resemble bunch of grapes hehe)

Question 4

Aveoli

Answer 4

• Chief gas-exchange units in lungs
• the membrane around each alveolus has pulmonary capillaries called alveolocapillary membrane

Question 5

What is the pulmonary circulation innervated by?

Answer 5

ANS

• vasodilation and vasoconstriction controlled by local and humoral factors mainly in terms of arterial oxygenation and acid-base status

Question 6

why would the pulmonary arterial system vasonconstrict?

Answer 6

• Alveolar hypoxia
• acidemia
• inflammatory mediators (histamine, serotonin, prostaglandins, and bradykinins)

Question 7

Chest wall consists of?

Answer 7

contains and protects thoracic cavity, consisting of skin, ribs, and intercostal muscles that lie between the ribs

• lined with a serous membrane called parietal plura
• while lungs are encased by a separate membrane called visceral pleura
• these two pleurae come into contact + slide over each other called pleural space

Question 8

Pulmonary system enables?

Answer 8

oxygen to diffuse into blood and co2 to diffuse out of blood

Question 9

Ventilation

Answer 9

• involuntary
• respiratory center in brainstem controls plus sympathetic and parasympathetic divisions of ANS [controlling airway caliber via contracting or relaxing of bronchial smooth muscles + rate and depth of ventilation]

Question 10

What kind of receptors in lungs?

Answer 10

1. neuroreceptors (mechanical aspects of ventilation)
2. Irritant receptors (expel unwanted things)
3. Stretch receptors (sense lung volume or expansion)
4. J-receptors (sense alveolar size)

• Chemoreceptors in circulatory sytem + brainstem (sense effectiveness of ventilation by pH monitoring of cerebrospinal fluid and o2 and CO2 content in arterial blood (PaO2 and PaCO2)

Question 11

What is involved in successful ventilation?

Answer 11

• interaction of forces and counterforces r/t muscles of inspiration and expiration
• alveolar surface tension
• elasticity of lungs + chest wall
• resistance to airflow

Question 12

Major muscle in inspiration?

Answer 12

Diaphragm

• When it contracts, it moves downward towards thoracic cavity (creating vacuum that causes air to flow into lungs
• NO MAJOR MUSCLES in expiration therefore normal elastic recoil permits passive expiration

Question 13

What does alveoli produce?

Answer 13

Surfactant via type II alveolar cells; it is a lipoprotein that lines the alveoli; the layer reduces alveolar surface tension and permits alveoli to expand more easily with air intake

Question 14

How does elastic recoil work?

Answer 14

Tendency of lungs and chest wall to return to their resting states after inspiration; these recoil forces produced from lungs and chest wall do oppose each other and pull on each other creating negative pressure of pleural space

Question 15

Compliance

Answer 15

• lung and chest wall distensibility during inspiration
• amount of surfactant production and elastic recoil of lungs + chest wall

Question 16

How is airway resistance determined?

Answer 16

• length, radius, and cross-sectional area of airways and by density, viscosity, and velocity of the gas
• usually LOW d/t large cross-sectional area of the lungs

Question 17

Effectiveness of gas transport depends on?

Answer 17

• Alveoli ventilation
• diffusion across alveolocapillary membrane
• perfusion of pulmonary and systemic capillaries
• diffussion between systemic capillaries and tissue cells

Question 18

Effecient gas exchange depends on?

Answer 18

• Even distribution of ventilation + perfusion within lungs
• This v/p is greatest in lung bases b/c alevoli in the bases are more compliant and perfusion is greater as a result of gravity

Question 19

Hemoglobin

Answer 19

a protein contained within red blood cells that helps tranpsort oxygen that diffuses into pulmonary capillary blood
* remainder of blood will be transported via plasma
* O2 is loaded onto hemoglobin d/t pressure exerted by PaO2 in the plasma; as pressure decreases @ tissue level, o2 dissociates from hemoglobin and enters tissues cells by diffusion AGAIN down by concentration gradient

Question 20

How does oxygen behave when entering body?

Answer 20

Diffusing down the concentration gradient (from high concentrations in alveoli to lower concentrations in capillaries) Diffusion stops when alveolar and capillary oxygen pressures equilibrate.

Question 21

CO2 nature

Answer 21

more soluble in plasma than o2 and co2 diffuses readily from tissues cells into plasma; CO2 returns to lungs dissolved in plasma => transported as bicarbonate or combined with blood proteins to form carbamino compounds (such as hemoglobin)

Question 22

Aging effects on pulmonary system

Answer 22

• decreased chest wall compliance and elastic recoil of lungs => reduces ventilatory reserve
• loss of alveolar wall tissue + alveolar enlargement resulting in loss of surface area for gas diffusion
• vital capacity (greatest amout of air that can be expelled from lungs) decreases and residual volume (remaining in lungs) increases // total lung capacity remains the same