Intro to Respiratory Physiology Lecture Sep 18

Question 1

WHat are the role of the pulmonary system?

Answer 1

Regulate plasma levels of oxygen and carbon dioxide

Regulate plasma pH

Protect against inhaled pathogens

Provide an adequate surface for gas exchange with the
external environment

Assure adequate alveolar air movement by alterations in
rate and depth of ventilation

Support vocalization of sound

Question 2

What are the three places of gas exchange in the pulmonary system?

Answer 2

1. Exchange of gases between the lungs and the atmosphere (ventilation)
2. Exhange of gases from the lungs and the blood
3. Exchange of gases in the blood to the cells

Question 3

WHat organs are involved in the respiratory system?

Answer 3

AIr enters through the nasal cavity and the mouth. It then goes through the pharynx and past the vocal cord to the larynx, trachea, bronchi, bronchioles, and alveoli in the lungs. The diaphragm is also involved in expanding the rib cage for insiration.

Question 4

What creates the negative pressur in the pleural space?

Answer 4

The lungs want to collapse and the ribs want to expand, which sets up a negative pressur in the pleural space.

Question 5

What does the diaphram do in inspiration?

In expiration?

Answer 5

To breathe in, the diaphragm contracts and pushes down into the abdomen at the same time as the intercostals contract and pull the ribs up. This means the volume of the chest wall and lungs increase and pressure decreases below atmospheric pressure, so air flows into the lungs.

To breath out, the diaphragm relxes and moves back up into its resting position, shrinking the lungs and increasing pressure, forcing the air back out.

Question 6

What gives rise to resistance to airflow in the pulmonary system?

What substances will icnrease or decrease flow?

Answer 6

THe diameter of the airways is the primary factor controlling air flow resistance.

In the upper airways, resistance will come maingly from physical obstruction like mucus or foriegn bodies.

The bronchioles is where the majority fo the resistance comes from. Bronchoconrstricion will icnrease resistance and decrease flow (paraxympathetic neurons, histamine, leukotrienes) and bronchodilation will decrease resistance and increase flow (carbon dioxide, epinephrine)

Question 7

What happens in a pneumothorax?

Answer 7

Normally the pleural space is at subatmospheric pressure

If air is introduced to the interpleural space, the pleura will be disrupted and the lung will collapse and the ribs will expand slightly

A collapsed lung will no longer expand when the diaphragm contracts down, so now the lung won’t be ventilated or profused - there will be no gas exchange

Question 8

What is used to measure lung volumes?

Answer 8

A spirometer

Question 9

What is the lung volume we breath in and out at rest?

What is the volume from our maximum inspiration and our maximum expiration?

WHat is the amount of air we can’t breathe out?

WHat is the total amoung of air we can put in th elungs?

Answer 9

Tidal volume

Vital capacity

Residual volume

Total lung capacity

Question 10

What make up the dead space int he respiratory system?

Answer 10

Any area that is not involved in gas exchange - nasal cavity, trachea, bronchi, bronchioles

Question 11

What is eupnea?

Answer 11

normal quiet breathing

Question 12

What is hyperpnea?

Answer 12

Increased respiratory rate and or volume in response to increased metabolism

like in exercise

Question 13

What is hyperventilation

Answer 13

Increased respiraotry rate and or volume WITHOUT icnreased metabolism

As in a panic attack

this will make you faint

Question 14

WHat is hypoventilation?

Answer 14

Decreased alvelar ventilation

as in shallow breathing, asthma, restrictive lung disease

Question 15

What is tachypnea

Answer 15

Rapid breathing; usually increased respiratory rate with decreased depth

as in panting

Question 16

What is dyspnea?

Answer 16

Difficulty breathin (a subjective feeling of shortness of breath)

Question 17

What is apnea?

Answer 17

Cessation of breathin

voluntary breath holding or depression of CNA control centers

Question 18

WHat are the four forms of hypoxia with their causes?

Answer 18

Hypoxic hypoxia (low arterial PO2 - high altitude, albeolar hypoventilation, decreased lung diffusion capacityl abnormal ventilation-perfusion ratio)

Anemia hypoxia (decreased total amount of O2 bound to Hb in blood loss, anemia, altered HBO2 cimbind, or carbon monoxide poisoning)

Ischemic hypoxia (reduced blood flow - as in heart failure, shock, or thrombosis)

Histotoxic Hypoxia (failure of cells to use O2 becuase cells have been poisoned by things such as cyanide - affect the mitochondria)

Question 19

What regulates ventilation in the short term?

Answer 19

In the short term, ventilation is regulated through chemoreceptors in the periphery and in the CNS (central chemoreceptors)

Question 20

WHere are peripheral chemoreceptros located?

WHat are they called?

What do they sense?

Answer 20

THey are glomus cells located in carotid and aortic arteris.

THey sense changes in PO2, pH and PCO2

Question 21

WHere are central chemoreceptors located and what do they sense?

Answer 21

Tey are located in the brain and sense changes in CO2

Question 22

How do peripheral chemoreceptors signal low PO2?

Answer 22

Carotid body oxygen sensors release neurotransmitters when the PO2 decreases.

1. Low PO2 causes K+ channels to close
2. cell dpolarizes
3. voltage gated CA++ channels open allowing CA2+ to enter the cell
4. CA2+ signal exocytosis of neurotransmitters
5. NTs act on receptor sare a neuron which releases an action potential that goes to the medullary centers to icnrease ventilation

Question 23

How do central chmoreceptors signal that CO2 has increased?

Answer 23

The central chemoreceptors monitor CO2 in the CSF>

1. If CO2 is high in the blood, it will also be high in the CSF because it can cross the blood brain barrier
2. The CO2 will bind to the central chemoreceptor
3. The respiratory control centers int he medulla will receive the message and increase ventilation

Question 24

What is the effector in pulmonary regulation of ventilation rate?

Answer 24

The medulla oblongata (also the pons)

THey receive messages from the higher brain centers and limbid system (emotional and ovluntary control), the medullary chemoreceptors (CO2), and the cartotid and aortic chemoreceptors (O2 and pH)

THey act on the pulmonary muscles to either increase or decrease inspiration

Question 25

What are the controlled variables that influence pulmonary function?

Answer 25

Plasma levels of O2, CO2, and pH are the controlled variables.

The system operates trough negative feedback

High CO2 in the plasma will result in an increase in ventilation, but as the increase in ventilation causes an increase in O2 in the plasma, the pathway is shut off through negative feedback