Dynamic Process of Breathing

Gr 11. Biology

Dynamic process of breathing

The mechanics and transport of breathing.

Inspired air path (mammals)

In mammals, inspired air travels through to the alveolus.

Alveolus structure

Each alveolus is composed of epithelium one cell thick.

Alveolus capillaries

Alveoli are surrounded by blood capillaries that are one cell thick.

Alveolus diffusion

This allows for diffusion of gases to occur.

Capillaries amount

There are about 30 billion capillaries in both lungs.

Capillaries per alveolus

There are about 100 capillaries per alveolus.

Alveolus description

Microscopic air bubble whose entire surface is bathed in blood. Name for singular alveoli

Air movement into lungs

Air is drawn into the lungs by creation of negative or sub-atmospheric pressure.

Boyle’s Law

When the volume of a given quantity of gas increases, its pressure decreases. Vice versa

Thorax expansion

The volume of the thorax increases during inspiration.

Lung expansion during inspiration

lungs expand.

Pressure when air enters lungs

When lung pressure is lower than atmospheric pressure, air enters the lungs.

Thoracic volume is increased by what 2 muscles

by diaphragm and external intercostal muscles.

Intercostal contraction during inspiration

Contraction causes rib cage to expand and go up

Diaphragm contraction during inspiration

Diaphragm lowers and assumes a flattened shape.

Inhalation effect

Increases volume and decreases pressure of lungs causing air to be drawn in.

Exhalation

Relaxation of external intercostals and diaphragm produces unforced exhalation.

Diaphragm during exhalation

Diaphragm relaxes and moves up.

Intercostals during exhalation

External intercostals relax; ribs move down and in.

Exhalation pressure

Volume decreases and pressure increases allowing air to exit.

Tidal volume

Normal volume of air displaced between normal inhalation and exhalation.

Tidal volume average

About 500 ml of air in a healthy person.

Vital capacity

The maximum amount of air expired after a forceful maximum inspiration.

Vital capacity equation

Tidal volume + inspiratory reserve volume + expiratory reserve volume = vital capacity.

Vital capacity men

Average for men = 4.6 L.

Vital capacity women

Average for women = 3.1 L.

Inspiratory reserve volume

Additional air taken in above tidal inhalation (deep breath in).

Expiratory reserve volume

Additional air forced out beyond regular tidal exhalation.

Normal breathing rate

12 – 20 breaths per minute.

Breathing rate control

CO2 levels control breathing rate.

Medulla function

The medulla oblongata senses CO2 levels.

Medulla response

When CO2 increases, a signal increases breathing rate.

Chemoreceptors role

Detect low O2 partial pressures in the blood.

Low O2 response

If O2 partial pressure is really low the medulla oblongata triggers a response.

Blood gas maintenance

Specific blood gas measurements must be maintained.

Oxygen in plasma

The amount of oxygen dissolved in plasma depends on PO2(pressure of oxygen) of alveolar air.

Oxygen solubility

Oxygen has low solubility in water so plasma carries limited oxygen.

Hemoglobin role

Help comes from hemoglobin found in RBCs.

Hemoglobin structure

Protein with four polypeptide chains and four heme groups.

Heme group

At the center of each heme group is an iron atom that binds one oxygen molecule.

Hemoglobin capacity

Each hemoglobin can carry 4 oxygen molecules.

Oxyhemoglobin

Hemoglobin links with oxygen in lungs forming oxyhemoglobin (bright red).

Deoxyhemoglobin

As blood passes capillaries, oxygen is released forming deoxyhemoglobin (dark red).

Blood vessel colours

Oxygenated vessels shown as red; oxygen-depleted shown as blue.

CO2 in plasma

About 8% of removed CO2 is dissolved in plasma.

CO2 bound to hemoglobin

About 20% of CO2 binds to hemoglobin on the protein portion.

Hemoglobin and CO2

CO2 binds to protein portion, so no competition for oxygen spots.(bc oxygen binds to iron)

CO2 conversion

72% of CO2 diffuses into RBCs and is turned into carbonic acid.

Carbonic acid role

Carbonic acid later diffuses out and accounts for blood pH.