Respiratory System

What is the goal of the respiratory system?

Air passageway and site of exchange of oxygen and carbon dioxide

Major characteristics of the Trachea and Bronchi

Cartilage

Withstand pressure changes

Major characteristics of the Bronchioles

Smooth muscle

Control air flow through bronchodilation/constriction

Major characteristics of the Alveoli

Thin layer (simple squamous epithelium) for exchange

Major characteristics of Elastic arteries

High amounts of elastic fiber

Withstand and maintain pressure created by pumping action of heart

Major characteristics of Muscular arteries and arterioles

High amounts of smooth muscle

Control blood flow through vasoconstriction/dilation

Major characteristics of Capillaries

Thin layer (simple squamous epithelium) for exchange

Alveolar Type I cells

Promote rapid diffusion of gases

Alveolar Type II cells

Produce pulmonary surfactant

Pulmonary surfactant

Decreases surface tension within the alveolus and prevents the collapse of alveoli

Why do the lungs have a natural tendency to collapse?

1. Elastic fibers surrounding the alveoli

2. Surface tension within the alveoli

Insufficient surfactant production can lead to ____ in newborns and in adults.

Respiratory distress syndrome

Asthma

Localized immune reaction that occurs in bronchi and bronchioles

Emphysema

Condition in which the alveoli of the lungs are damaged and enlarged

How does the ventilator help a person breathe?

Pushes air into the lungs and letting it out when they can’t breathe well on their own

Makes sure the body gets enough oxygen and gets rid of carbon dioxide.

Atmospheric pressure

Pressure of air outside the body

Intrapulmonary pressure

Pressure in the lungs

Intrapleural pressure

Pressure within the intrapleural space (pleural cavity)

Why is intrapleural pressure always lower than intrapulmonary pressure? What is the significance of this?

The pressure difference pulls lungs outward, keep the lungs against the thoracic wall and prevents them from collapsing.

During inspiration (intrapulmonary pressure is made ___ than the atmospheric pressure)

Lower

During expiration (intrapulmonary pressure is made ___ than the atmospheric pressure_

Higher

During normal inspiration, do the diaphragm and external intercostals contract or relax?

Contracts

During normal inspiration, what happens to the size of the thoracic cavity?

Expands

During normal inspiration, what happens to the pressure inside the thoracic cavity?

Decreases

During normal inspiration, does air move in or out of the thoracic cavity?

In

During normal expiration, do the diaphragm and the external intercostals contract or relax?

Relax

During normal expiration, what happens to the size of the thoracic cavity?

Reduces

During normal expiration, what happens to the pressure inside the thoracic cavity?

Increases

During normal expiration, does air move in or out of the thoracic cacity?

Out

What muscles are involved in forced inspiration?

Neck muscles

What muscles are involved in forced expiriation?

Abdominal muscles

Inhalation

1. External intercostals and diaphragm contract

2. This pulls on the parietal pleura which pulls on the visceral pleura

3. This pulls on the outside of the alveoli, enlarging them

4. Decreases the pressure in the alveoli, pulling air into them. (High pressure outside, low pressure inside, air flows in)

Exhalation

1. External intercostals and diaphragm relax

2. Pushes on the pleural membrane and the alveoli

3. Pressure increases in the alveoli, forcing out air

Factors that promote the collapse of the lungs

1. Elastic fibers surrounding the alveoli

2. Surface tension within the alveoli

Factors that counter the lungs natural tendency to collapse

1. Pleural cavity always has a lower pressure compared to the lungs

2. Production of pulmonary surfactant

What can happen if the countering mechanisms fail?

1. Pneumothorax

2. Respiratory distress syndrome

What causes intrapleural pressure to be lower than intrapumonary pressure?

Due to the elastic recoil of both the chest wall and lungs moving opposite directions

What causes intrapulmonary pressure to be lower than atmospheric pressure?

The diaphragm contracts causing lung volume to increase

Under normal conditions, the region that has the highest pressure of oxygen is ____.

Alveoli of lungs

The region that has the highest pressure of carbon dioxide is ____.

Tissues

Alveolar exchange happens due to pressure differences in the gases between ____ and the ____.

Alveoli; Blood

Systemic exchange happens due to pressure difference in the gases between ____ and the ____.

Systemic cells; Blood

Three main factors affecting diffusion of gases in alveolar exchange

1. Concentration gradient

2. Surface area

3. Diffusion distance

What is the major challenge in transporting gases in the blood?

Oxygen and carbon dioxide are not very soluble in water, which is the major component of the blood plasma

Alveolar exchange of oxygen

Oxygen is packed into empty hemoglobin at the lungs, allowing for increased diffusion from the alveoli

Systemic exchange of oxygen

Oxygen is released from hemoglobin at the tissues as free O2 in the blood so that it van diffuse into the systemic cells

Carbon dioxide transport

Only a small amount of CO2 is dissolved in the blood plasma and another small amount is transported by hemoglobin. However, most CO2 is transported as bicarbonate in the plasma.

Systemic exchange of CO2

CO2 is converted in the RBC to carbonic acid and bicarbonate using the enzyme: carbonic anyhdrase. This effectively removes CO2 from the blood so more can diffuse in from the tissues

Alveolar exchange of CO2

Carbonic acid and bicarbonate are converted back into CO2 at the lungs (reverse reaction) so it can escape into the alveoli

Is it easier for the body to monitor concentration of oxygen or carbon dioxide in the blood?

Carbon dioxide

Equation for CO2

CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+

Rise in CO2 or H+ can be detected by ____.

Chemoreceptors on the blood vessels and medulla

Pneumothorax

Collapsed lung

Respiratory Distress Syndrome

Lungs can’t properly stay open

High altitude

Less oxygen in air

Pulmonary edema

Build of fluid in lungs