Unit 6 - Respiratory System

Respiration

The entire process of exchanging gases between the atmosphere and body cells

The respiratory system consists of

passages that bring in air and transport it into the body where our body uses it in order to sustain life.

Ventilation

moving air in and out of the lungs (Steps 1 or 4)

External Respiration

Exchange of gases between the air in the lungs and the blood (Steps 2 or 3)

Internal Respiration

Exchange of gases between the blood and the body cells (Step 3 or 2)

Celluar Respiration

Oxygen utilization by body cells (Step 4 or 1)

Why do we breathe?

- Our body cells need oxygen.

- As they use oxygen, carbon dioxide is produced as a byproduct.

- Too much CO2 will lower pH of blood and threaten homeostasis.

The Functions of the Respiratory System:

- Provide Oxygen

- Eliminate CO2

Upper respiratory tract organs

Nose, nasal cavity, and pharynx

Lower respiratory tract organs

Larynx, trachea, bronchial tree, and lungs

Nose:

- Two nostrils

- Internal hairs, which prevent foreign objects from entering

- Make air "cleaner"

Nasal Cavity

- Hollow space behind nose

- Air heated by the blood

- Mucous membrane

Pharynx:

Located posterior to mouth

Passageway for food and air

Advantages of breathing in your nose:

- Filters/cleans = nose hairs pick up foreign objects, prevent harmful things from coming into your body.

- Warms = blood in nasal cavity warms the air to get it to body temperature.

- Moistens air too!

Larynx:

- Passageway for air moving in and out of trachea

- Houses the vocal cords

Trachea:

- Flexible cylinder tube that extends downward from larynx.

- Made of "C" rings (cartilage rings)

Structures in Larynx That Prevent Food and Water from Entering Lungs:

Epiglottis

Glottis

Epiglottis:

- Structure that covers the larynx when the person swallows

- Helps prevent food and liquids from entering the air passages

Glottis:

- Opening between vocal cords in larynx

- Closes when food is eaten to help prevent food or liquid from entering the trachea

Bronchial Tree

Consists of branched airways leading from the trachea to the sacs in the lungs

Sections of the Bronchial

- Primary bronchi

- Secondary bronchi

- Tertiary bronchi

- Bronchioles

- Alveolar sacs

- Aleveoli (Alveolus)

Alveoli:

- Pulmonary arterioles bring blood to the alveoli, pulmonary venules take blood away from the alveoli.

- Consists of thin membrane where oxygen occurs.

- During gas exchange, oxygen diffuses through alveolar walls (simple squamous epithelium) and enters blood stream. Crabon dioxide diffuses through walls and enters alveoli.

- Pulmonary capillaries wrap around these alveoli in which gas exchange occurs.

Respiratory Membrane

- The wall of the Alveoli and of the pulmonary make this up

- Made up of two layers of simple squamous epithelium

- This is where gas exchange occurs between the alveoli and the blood

Lungs

Soft, spongy, cone-shaped organs located in the thoracic cavity

The right lung is ______ than the left lung

Larger

Right Lung is divided into _____ sections

3 - Superior lobe, Middle lobe, Inferior lobe

Left Lung is divided into _______ sections

2 - Superior and Inferior

Fissures:

A groove or cut in an organ, separates out the lobes!

Oblique Fissure:

Right Lung and Left Lung

Horizonatal Fissure:

ONLY right lung

Pleura

- Pleura = membrane

- Parietal = covers the walls of the cavities

- Visceral = covers the viscera (organs) of each cavity

Parietal Pleura:

Covers thoracic wall compartments

Visceral Pleura:

Covers lungs

Function of the Pleura

- Aids in optimal functioning of the lungs during respiration.

- The pleurae are coated with lubricating pleura fluid which allows the pleurae to slide effortlessly against each other during ventilation (decrease friction).

Breathing

is the movement of air from the outside of the body into the bronchial tree and alveoli; followed by reversal of this air movement.

Define inspiration

Bringing air into the body.

Define expiration

Bringing air out of the body.

Boyle's Law

- Pressure and volume are inversely related.

- Volume down, pressure UP

- Volume up, pressure DOWN

- Applies to the lungs.

Pleura Movement:

- The pleura work together always.

- Thus if the thoracic cage increases in size, the lungs increase in size as well.

Inspiration

Air comes into lungs when we increase volume (760mm vs 758mm) Air travels from hight to low pressures into the lungs

Muscles used for inspiration

Diaphragm - contracs and moves downward External intercostals muscles - between our ribs; contract and raises the ribs

Forced Inspiration:

A deeper than normal breath - Diaphragm and external intercostals muscles contract more forcefully and the Pectoralis minor and the Sternocleidomastoid are used to pull the thoracic cage bigger

Pressure in lungs gets lower than 758

Expiration

The forces that cause expiration come from elastic recoil of lung tissues

- When this happens, the diaphragm is pushed upwards (back to resting position), the volume of lung DECREASES, thus the pressure inside the lungs INCREASES

- 762mm

- This is a passive process: Involves no contractions of muscles.

Forced Expiration:

If a person needs to exhale more than normal

- Internal intercostals muscles.

- Abdominal muscles are also used to force air out.

- Pressure greater than 762

Surfactant

- Secreted continuously into alveoli.

- Reduces tendancy to collapse by reducing surface tension.

- Makes breathing in easy.

Respiratory Distress Syndrome (RDS):

- When you do not have enough surfactant.

- Cannot overcome surface tension force to inflate alveoli.

- Now we have synthetic surfactant.

Pneumonia

- Viral or bacterial.

- Alveolar linings swell.

- Fluids enter your lungs.

- Result = less surface area on alveoli = decrease gas exchange.

Atelectasis

- Collapsed lung.

- Due to an obstruction of a respiratory tube.

- Airways beyond obstruction collapse as air is taken in.

Yawning

- Forceful inspiration

- No known reason for yawning! Just theories!

Respiratory Areas

- Groups of neurons (chemoreceptors) in the brainstem comprise the respiratory areas, which control breathing.

- Located in the pons and the medulla.

Partial Pressure:

In a mixture of gases (such as in air), each gas accounts for a portion of the total pressure the mixture produces.

- The amount of pressure of each gas in the mixture.

- Also proportional to the concentration of the gas.

Dissolved Gases:

- Gas molecules in the air may dissolve in liquid.

- This occurs with Oxygen and Carbon Dioxide dissolving into blood.

- Are not attached to hemoglobin or anything, just "hang out" in plasma.

Diffusion at Alveoli:

Molecules diffuse from regions where they are in higher concentration toward regions where they are in lower concentration.

- Molecules move in the direction of the concentration gradient.

External Respiration Gas Exchange:

Oxygen:

- In the alveoli: PO2 = 104 mm Hg

- In the pulmonary artery (deoxygenated blood): PO2 = 40 mm Hg

Carbon Dioxide:

- In the alveoli: PCO2 = 40 mm Hg

- In the pulmonary artery:PCO2 = 45 mm Hg

Which way does each gas move?

- Oxygen goes from alveoli to pulmonary artery.

- Carbon Dioxide goes from pulmonary artery to alveoli

Oxygen Transport:

two main wasy fo 02 transportation:

- Oxygen (almost 98%) is carried in the blood bound to the protein hemoglobin in red blood cells

- The remainder (2%) is dissolved in plasma

Each hemoglobin molecule can bind up to four oxygen molecules

Release of Oxygen:

- Oxygen is given up to body cells to be used.

- The chemical bonds between oxygen and hemoglobin are unstable

- Thus oxygen is given up to body cells easily.

Factors that influence amount of oxygen given up:

- Increase CO2 in blood

- Lower pH (acidity)

- Increase temperature

Carbon Dioxide Transport:

Three ways for transport:

- Dissolved Plasma (7%)

- Binds to hemoglobin (15-25%)

- Bicabonate ion (as much as 70%)

CO2

An increase in CO2 in the blood leads to a decrease in blood pH (acidic). Thus we need to breathe it out

After your body cells utilize the oxygen

CO2 (from body cells) + H2O (plasma) -> H2CO3

H2CO3 is carbonic acid

H2CO3 -> H+ + HCO3- (bicarbonate ion)

HCO3- is the bicarbonate ion in which carbon dioxide is mainly carried around in.

H+ leads to higher blood acidity (lower pH).

When breathe out, reverse the reaction:

H+ + HCO3- -> H2CO3 -> CO2 (breathe this out) + H2O

Why? Because we cannot breathe out HCO3-. We need to breathe out CO2 (gas).

Blood pH

Normal blood pH is 7.35-7.40 (slightly basic).

Two main organs that help balance:

-Lungs: breath our CO2

- Kidneys: Urinate out hydrogen ions

Acidosis

when blood pH is below 7.35 (too acidic)

Alkalosis

when blood pH is above 7.45 (too basic)

Hyperventilation

Stress, panic

Fast, quick breathing

Lose CO2 rapidly = causing increase pH (basic)

Breathe in a bag to change partial pressure

Purpose of Breathing

- To get rid of CO2

- If you have too much CO2, need to breathe fast to get CO2 out

Respiratory Volume:

- There are different distinct volumes of air in the lungs.

- At any given time, there is a different amount of air in the lungs.

- We have ways of computing and figuring out how much air in the lungs at any given time.

Respiratory Cycle:

One inspiration followed by one expiration.

Tidal Volume (TV)

- The volume of air that enters or leaves during a respiratory cycle.

- Usually about 500 ml of air

Inspiratory Reserve Volume (IRV)

- The additional volume of air is inhaled during forced inspiration.

- Usually about 3,000 ml of air.

Expiratory Reserve Volume (ERV):

- The additional volume of air exhaled during a forced expiration

- Usually about 1,100 ml of air.

- This is in addition to the tidal volume (thus one could get up to 1,600 ml of air out of their lungs).

Residual Volume (RV):

- However, even after the most forceful expiration, about 1,200 ml of air remains in the lungs.

- ALWAYS have residual volume in lungs.

Vital Capacity (VC):

VC = IRV + TV + ERV

- The total amount of air you can breathe in and out.

- Usually about 4,600 ml

Inspiratory Capacity (IC):

IC = TV + IRV

- Maximum volume of air a person can inhale.

- Usually about 3,500 ml

Functional Residual Capacity (FRC):

FRC = ERV + RV

- The volume of air that remains in the lungs following a resting expiration.

- Usually about 2,300 ml

Total Lung Capacity (TLC):

TLC = IRV + TV + ERV + RV

- The total amount the lungs can hold.

- Usually about 5,800 ml.

- This varies with age, sex, and body size!