The Respiratory System

Part Two

Breathing

Respiration Center - Brain

• Medulla oblongata– (can’t control

with our will)– Stimulates of diaphragm

and (rib) muscles for

• Stretch receptors– Receptors that for

the nervous which give on

mechanical pressure or – stretch receptors in alveoli limit

depth to over inflation by expiration

Pressure

• air moves in or out of lungs to

pressure with atmosphere– air moves from

area of pressure to area of pressure

• an expanded volume will lower the pressure and allow air to into the lungs through the

passages• Upon inspiration, the

pressure in the alveoli is on the order of 2-3 mmHg below the atmospheric pressure of 760 mmHg

• The relaxing of the diaphragm reduces the volume and

the pressure, allowing air to flow out of lungs• provides a

pressure some 3 mmHg above atmospheric pressure to accomplish expiration.

Inspiration/Expiration

Inspiration/Expiration

Inspiration1. Diaphragm and the

dome shape changes to a flat shape

2. External muscles contract and ribs

3. Volume of cavity increases

4. Pressure inside thoracic cavity

Expiration1. Diaphragm and

returned to its natural

shape2. External

muscles relax3. Volume of

cavity decreases4. Pressure inside thoracic

cavity

External Respiration

Gas exchange between the air and lungs

Red Blood Cells

• In each red blood cell, there are approximately hemoglobin

• Each hemoglobin molecule binds to oxygen

• Researchers believe that each molecule also binds 4 carbon dioxide molecules (not confirmed)

External• In lungs, O2 from air diffuses into and

CO2 from blood diffuses into air within – i.e. O2 diffuses down into

blood, while CO2 diffuses into air

Oxygen

• 1.5% of oxygen is as

gas• 98.5% binds to

hemglobin (Hb) at the and is

transported as HbO2 or

O2 + Hb → HbO2

Carbon Dioxide

• Leaves the red blood cell and out into the alveolar air– Leaves as:

• Dissolved gas• Dissociated from

• Broken down from

CO2(g) + H2O(l) H2CO3(aq) HCO3–(aq) + H+(aq)

Internal Respiration

Gas exchange between the blood and body cells

Internal

• In tissues, from blood diffuses into tissues and from tissues into

Oxygen

• Oxygen from the hemoglobin molecule due to temperature and differences

• Oxygen is now free to the concentration gradient and diffuse out of the and into the tissue

• hemoglobin molecule will bind H+ to become

concentration

Carbon Dioxide• 7% dissolves in

and is as solution

• 23% diffuses into , binds to hemoglobin, and is as

(HbCO2)

CO2 + Hb → HbCO2

• 70% diffuses in RBC and is to HCO3– and H+ by

CO2(g) + H2O(l) → H2CO3(aq) → HCO3–(aq) + H+(aq)

– HCO3 (bicarbonate ions) move out from RBC and is transported via plasma– H+ combines with to form reduced (HHb)

• H+ + Hb → HHb• Therefore, HCO3

– and Hb act as to help maintain in blood

Regulating Breathing RateBreathing rate and depth to maintain O2 and CO2 levels in blood, which are by in the medulla oblongata and and bodies (found in the carotid and aortic arteries)

• Medulla Oblongata– detects H+ concentration

(decreasing pH) caused by increased CO2 in blood

– causes to contract

• Carotid and Aortic Bodies– detect O2 in blood causing to

contract

By end of this section you should be able to:

• identify and give functions for each of the following:– nasal cavity– pharynx– larynx– trachea– bronchi– bronchioles– alveoli– diaphragm and ribs– pleural membranes– thoracic cavity

• explain the roles of cilia and mucus in the respiratory tract• explain the relationship between the structure and function of

alveoli

• describe the interactions of the following structures in the breathing process:– respiratory centre in the medulla oblongata– lungs– pleural membranes– diaphragm– intercostal (rib) muscles– stretch receptors

• compare the processes of inhalation and exhalation• explain the roles of carbon dioxide and hydrogen ions in stimulating

the respiratory centre in the medulla oblongata• explain the roles of oxygen, carbon dioxide, and hydrogen ions in

stimulating carotid and aortic bodies

• describe the exchange of carbon dioxide and oxygen during internal and external respiration, including

– location of exchange – conditions that favour exchange (e.g., pH, temperature)

• explain the roles of oxyhemoglobin, carbaminohemoglobin, reduced hemoglobin, bicarbonate ions, and carbonic anhydrase in the transport of carbon dioxide and oxygen in the blood

• write the chemical equations for internal and external respiration

Mandatory Vocabulary

alveoli, aortic bodies, bicarbonate ions, bronchi, bronchioles, carbaminohemoglobin, carbon dioxide, carbonic anhydrase, carotid bodies, cilia, diaphragm, exhalation, external respiration, hydrogen ions, inhalation, intercostal (rib) muscles, internal respiration, larynx, lungs, mucus, nasal cavity, oxygen, oxyhemoglobin, pH, pharynx, pleural membrane, reduced hemoglobin, respiratory centre in the medulla oblongata, respiratory tract, ribs, stretch receptors, thoracic cavity, trachea