Respiratory System

Respiration External Respiration:

exchange of oxygen and carbon dioxide between the air and the cells of the lungs.

Respiration

Internal Respiration: exchange of gases between body cells and blood

Respiration Cellular respiration: chemical

reactions in cells that use oxygen and produce carbon dioxide

Respiration

Breathing or ventilation: the process by which air enters and leaves the respiratory organs

Always involves a moist, thin membrane

Lower Animals Single celled and smaller

animals can use diffusion alone: ‘breathe’ through their moist skin or membrane

Lower Animals

Fish breathe using gills: put moist membrane inside, high surface area

Humans

And terrestrial animals use lungs

also high surface area, moist

Anatomy Nasal

chambers –Air is filtered, warmed, moistened by hairs, mucous and sinus cavities

Anatomy

Oral cavity: second entryway for air

Larger opening, less filtering,

Anatomy

Both nasal and oral cavities open to the pharynx

Anatomy

The epiglottis

prevents foodfrom entering

thetrachea.

Anatomy

The trachea (windpipe) is lined with rings of cartilage for support

Lined with cilia to sweep debris away

Anatomy

Membranes of the upper respiratory passages are ciliated

This helps to remove particles as they enter

Anatomy

The larynx (voicebox) – contains vocal cords

Anatomy

Trachea branches into two bronchi

These branch into smaller bronchioles

Anatomy No cartilage in bronchioles

Contain smooth muscle that contracts and expands with each breath

Anatomy Asthma is the over -constriction

of these muscles

AnatomyAlveoli (sing. Alveolus) are air

sacs at ends of bronchioles Single cell thick, moist surrounded by a capillary bed-

site of gas exchange

AnatomySurfactant – a

lipoprotein secreted by lung tissue to prevent collapse of alveoli

A premature infant with respiratory distress syndrome

Anatomy

Pleural membranes surround the lungs

Fluid between reduces friction

Gas Exchange gas moves from areas of high

pressure to low pressure

pleural pressure = pressure in the lungs

atmospheric pressure = air pressure outside lungs

Gas Exchange

inspiration occurs when pleural pressure is less than atmospheric pressure

expiration occurs when pleural pressure is greater than atmospheric pressure

Muscles Involved in Breathing

Diaphragm is a dome-shaped muscle at base of ribcage

Muscles Involved in Breathing

Intercostal muscles are between ribs

Inspiration diaphragm contracts and moves

downward

intercostals move ribcage up and out

the net result is an increase in lung volume and a decrease in pleural pressure

Air moves into the lungs

Expiration diaphragm relaxes and domes up

intercostal muscles relax

the net is result is a decrease in lung volume and an increase in pleural pressure

gas moves out

Regulation of Breathing

Chemoreceptors in medulla detect carbon dioxide

most

important

Regulation of Breathing

As carbon dioxide levels increase, nerves from brain send messages to respiratory muscles to increase breathing rate

Regulation of Breathing

Oxygen receptors:

- in aorta and carotid arteries

-are a back up for when CO2 stays normal but oxygen is low

ex) high altitude

Oxygen Transport Oxygen binds with hemoglobin to

form oxyhemoglobin

Fact: every RBC carries 265 million molecules of hemoglobin!

Oxygen Transport

Each Hb molecule can carry four oxygen molecules

Hb + O2 Hb(O2 )4 Oxyhemoglobin

Oxyhemoglobin Dissociation

Hemoglobin’s affinity for oxygen decreases as the acidity (carbon dioxide levels) increase

Oxygen delivery increases to tissues in need

Carbon Dioxide Transport 20 times more soluble than oxygen

Carried in three ways:1. some is dissolved in blood plasma

(about 10%) 2. Combines with hemoglobin to form

carbaminohemoglobin (HbCO2)-competes with oxygen

Carbon Dioxide Transport

3. Most carbon dioxide(70%) combines with water in the plasma to form carbonic acid which then breaks down into bicarbonate ions.

Reaction is catalysed by carbonic anhydrase enzyme

Carbon Monoxide

Competes with oxygen for sites on hemoglobin – carboxyhemoglobin

200X more affinity for Hb than oxygen

Carbon Monoxide Hemoglobin combined with CO is

called carboxyhemoglobin Colorless, odorless Skin turns bright pink

Nonrespiratory Air Movements

Coughing and sneezing: contraction of diaphragm with sudden

opening of glottis Dislodges particles on membranes

Nonrespiratory Air Movements

Hiccuping: sudden diaphragmatic contractions

Many causes; may be related to stomach activity

Nonrespiratory Air Movements

Laughing: epiglottis half-closes the larynx, so

that air intake occurs irregularly, making you gasp

A social signal – often initiated by group leaders

Nonrespiratory Air Movements

Yawning: Inspiration with stretching of facial muscles

Contagious, not due to gas levels in blood

Also is a social signal, wolves

High AltitudeBody adapts by:

Short term – increasing force and rate of breathing

Increasing production of RBC’s using hormone erythropoeitin (EPO)

Increases lung capacity

Breathing Disorders

Hyperventilation

Disorder caused by stress, etc. – lowered carbon dioxide levels due to overbreathing

Causes oxygen chemoreceptors to increase in sensitivity

Causes excessive breathing, which further decreases carbon dioxide levels- vicious cycle!

The ‘Bends’ When scuba diving,

nitrogen dissolves in blood – due to increased pressure

When ascending, the pressure drops and the nitrogen gas forms bubbles in blood vessels

Treatment – raise pressure and release it slowly – allowing gas to be diffused out of blood

Hyperbaric Chamber

Bronchitis Inflammation of the airways due

to infection

May be chronic, especially in smokers

Pneumonia Due to infection, lungs produce

fluid Can cause ‘drowning’

Pneumothorax

Collapsed lung

Emphysema

Now called COPD (Chronic Obstructive Pulmonary Disease)

Alveoli lose elasticity and can expand but not contract

Eventually lose surface area in lungs

Often due to smoking or mining

May need supplemental oxygen

Lung Cancer

Virtually always due to smoking Takes on average 20 years Usually begins on bronchioles Not diagnosed until spread Poor prognosis