Respiration

and Breathing

Anatomy

Know the pathway for inhaled and exhaled air in the respiratory system

Know terms such as nasal cavity, oral cavity, pharynx, epiglottis, larynx, trachea, lung, bronchi, bronchioles, intercostal muscles, diaphragm, alveoli

Breathing Movements

Know what happens to the diaphragm and the internal and external intercostal muscles when inhaling and exhaling– Understand the pressure of the chest

cavity and how it facilitates the moving of air in and out

Regulation of Breathing Breathing movements are

controlled by the medulla oblongata in the brain

information about the amount of CO2 and O2 is directed by chemoreceptors which send a message to the medulla – there are separate receptors

for CO2 (more sensitive) and O2

What Happens when CO2 levels increase? chemoreceptors sense increase in CO2

the diaphragm and intercostal muscles’ activity increases (stimulated by medulla oblongata)

this increases breathing movements and therefore increases the amount of CO2 being exhaled

when CO2 levels fall, the chemoreceptors become inactive and breathing rates return to normal

What Happens when CO2 levels increase? Drugs like morphine and barbiturates (aka.

Downers/depressants) can make the medulla less sensitive to CO2 levels and as a result, breathing rate decreases which could eventually cause death

Why can’t you hold your breath forever? Why do people breathe into paper bags when

having an anxiety attack?

Feedback LoopHigh CO2

Chemoreceptors

Medulla

Diaphragm Intercostals

Breathing Rate Increases

Less CO2 absorbed in

blood inactivates chemoreceptors

What Happens When O2 Levels Are Low?

oxygen chemoreceptors called the carotid and aortic bodies detect when oxygen levels are low and become stimulated

a message is sent to the medulla the medulla sends nerve impulses to the diaphragm

and the ribs begin breathing movements this will increase the amount of oxygen in the blood the O2 receptors are only called into action

when O2 levels fall and CO2 levels remain in the normal range

What Happens When O2 Levels Are Low?

Some examples– when you hold your breath, your O2 levels drop while the

CO2 levels increase and the high CO2 levels will initiate breathing movements

– in high altitudes where there is less O2 present, the opposite will happen. Low levels of O2 is not accompanied by high CO2 levels, the oxygen chemoreceptors initiate breathing movements

– when carbon monoxide poisoning occurs, CO (carbon monoxide) competes with O2 on the binding sites of the hemoglobin molecules in the blood. This reduces the O2 levels in the blood, stimulating the oxygen chemoreceptors to initiate breathing movements

Feedback LoopLow Blood O2

Chemoreceptors

Medulla

Diaphragm Intercostals

Breathing Rate Increases

Breathing Graphs

Breathing Graphs Tidal Volume (TV) – volume of air being inhaled and exhaled

during normal breathing. Inspiratory Reserve (IR) – maximum amount of air that is

inhaled above tidal volume. Expiratory Reserve (ER) – amount of air that can be exhaled

after normal exhalation/ Residual Volume – volume of air that always stays in the lungs Vital Capacity (VC) – total volume of air that the lungs can

inhale and exhale. Vital Capacity = Tidal Volume + Inspiratory Reserve +

Expiratory Reserve VC = TV + IR + ER Total capacity = vital capacity + residual volume

Respiration and Blood

Respiration and Blood

Oxygen Transport– O2 in the alveoli diffuses into the fluid

around the cells surrounding the capillary bed

– O2 then diffuses through the capillary walls

and into the blood plasma and the oxygen binds on the hemoglobin molecules in the red blood cell

Respiration and Blood

Carbon Dioxide Transport– 23% of CO2 is carried on hemoglobin– 7% is carried in plasma– 70% of CO2 (from cellular respiration) enters the

red blood cells and in order to maintain blood pH, is chemically converted to carbonic acid (H2CO3) in a reaction that is catalyzed by carbonic anhydrase (an enzyme)

• carbonic acid molecules dissociate forming bicarbonate ions and hydrogen ions

• bicarbonate diffuses out of RBC into the plasma

Respiration and Blood

Carbon Dioxide Transport– when blood rich in CO2 reaches the lungs,

bicarbonate ions combine with hydrogen ions, reforming carbonic acid

• carbonic acid dissociates, forming water and CO2 which diffuses out of the blood and into the alveoli

• when present in normal amounts, the ratio of carbonic acid to bicarbonate creates an acid-base balance in the blood, helping to keep the pH at a level where the body's cellular functions are most efficient

Respiration and Blood

Carbon Dioxide Transport– CO2 travels from the capillaries to the

alveoli, this is driven by concentration differences (the concentration of CO2 in the capillaries is slightly higher than in the alveoli)

– CO2 is then expelled out of the lungs in exhalation

Respiration and Blood Reaction Summary

CO2 + H2O H2CO3 (carbonic acid) In RBC

carbonic anhydrase

Respiration and Blood Reaction Summary

CO2 + H2O H2CO3 (carbonic acid) In RBC

carbonic anhydrase

H2CO3 HCO3- + H+ In RBC then to

plasma

(bicarbonate)

Respiration and Blood Reaction Summary

CO2 + H2O H2CO3 (carbonic acid) In RBC

carbonic anhydrase

H2CO3 HCO3- + H+ In RBC then to

plasma

(bicarbonate)

HCO3- + H+ H2CO3 In

RBC

Respiration and Blood Reaction Summary

CO2 + H2O H2CO3 (carbonic acid) In RBC

carbonic anhydrase

H2CO3 HCO3- + H+ In RBC then to plasma

(bicarbonate)

HCO3- + H+ H2CO3 In RBC

H2CO3 CO2 In RBC

  H2O

The Function of the Hydrogen Ions the H+ ions help to dislodge O2 from the hemoglobin

causing O2 to diffuse into the tissues by removing H+ ions from the plasma, the hemoglobin

acts as a buffer when the deoxygenated blood from the veins reaches

the lungs, O2 dislodges the H+ from the hemoglobin the free H+ combines with bicarbonate to eventually

form CO2 and H2O this is called blood buffering, it helps to maintain

blood pH

Respiratory System Disorders Laryngitis – swelling of the larynx which leads to

temporary voice loss Respiratory Distress Syndrome – newborn

babies lack the lipoprotein coating the alveoli. Extreme force is required by the baby to breathe. May result in death

Pleuracy – inflammation of the pleural membranes (a thin membrane that covers the outer surface of the lung) caused by rubbing together. This results in a fluid buildup in the chest. Exhaling becomes more difficult.

Respiratory System Disorders Bronchitis – caused by a bacterial or viral infection.

It causes mucus cells of the respiratory pathway to secrete more mucus. Tissue swelling occurs and air passages narrow, restricting breathing in and out

Asthma – sufferers require extreme force to exhale, as a result, more air comes in than goes out. Caused by allergies (causing tissues to swell), or muscle spasms on the surface of the bronchioles

Sinusitis – inflammation of the sinuses, mucus discharge and blockage of the nasal passages. Leads to headaches.

Respiratory System Disorders Emphysema – inhalation is easier than exhalation.

The buildup of pressure on the alveoli causes them to rupture, thus reducing the surface area for gas exchange. Breathing rate will increase

Pneumonia – inflammation of the lungs caused by bacteria, viruses, or inhalation of irritating gases. Leads to cough and fever, shortness of breath, chills, sweating, blood in mucus

Lung Cancer – cancer cells destroy healthy lung tissue Cystic Fibrosis – the mucus coating on the insides of

the lungs becomes very sticky leading to breathing problems (genetic condition)