Respiratory System

Respiration External Respiration : exchange of oxygen and carbon dioxide between the air and the cells of the lungs. 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 Internal Respiration: exchange of gases between body cells and blood

Respiration Cellular respiration: chemical reactions in cells that use oxygen and produce carbon dioxide 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 Breathing or ventilation: the process by which air enters and leaves the respiratory organs Always involves a moist, thin membrane Always involves a moist, thin membrane

Lower Animals Single celled and smaller animals can use diffusion alone: ‘breathe’ through their moist skin or membrane 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 Fish breathe using gills: put moist membrane inside, high surface area

Humans And terrestrial animals use lungs And terrestrial animals use lungs also high surface area, moist also high surface area, moist

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

Anatomy Oral cavity: second entryway for air Oral cavity: second entryway for air Larger opening, less filtering, Larger opening, less filtering,

Anatomy Both nasal and oral cavities open to the pharynx Both nasal and oral cavities open to the pharynx

Anatomy The epiglottis The epiglottis prevents food from entering the trachea.

Anatomy The trachea (windpipe) is lined with rings of cartilage for support The trachea (windpipe) is lined with rings of cartilage for support Lined with cilia to sweep debris away Lined with cilia to sweep debris away

Anatomy Membranes of the upper respiratory passages are ciliated Membranes of the upper respiratory passages are ciliated This helps to remove particles as they enter This helps to remove particles as they enter

Anatomy The larynx (voicebox) – contains vocal cords The larynx (voicebox) – contains vocal cords

Anatomy Trachea branches into two bronchi Trachea branches into two bronchi These branch into smaller bronchioles These branch into smaller bronchioles

Anatomy No cartilage in bronchioles No cartilage in bronchioles Contain smooth muscle that contracts and expands with each breath Contain smooth muscle that contracts and expands with each breath

Anatomy Asthma is the over -constriction of these muscles Asthma is the over -constriction of these muscles

Anatomy Alveoli (sing. Alveolus) are air sacs at ends of bronchioles Single cell thick, moist Single cell thick, moist surrounded by a capillary bed- site of gas exchange surrounded by a capillary bed- site of gas exchange

Anatomy Surfactant – a lipoprotein secreted by lung tissue to prevent collapse of alveoli A premature infant with respiratory distress syndrome

Anatomy Pleural membranes surround the lungs Pleural membranes surround the lungs Fluid between reduces friction Fluid between reduces friction

Gas Exchange gas moves from areas of high pressure to low pressure gas moves from areas of high pressure to low pressure pleural pressure = pressure in the lungs pleural pressure = pressure in the lungs atmospheric pressure = air pressure outside lungs atmospheric pressure = air pressure outside lungs

Gas Exchange inspiration occurs when pleural pressure is less than atmospheric pressure inspiration occurs when pleural pressure is less than atmospheric pressure expiration occurs when pleural pressure is greater 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 Diaphragm is a dome-shaped muscle at base of ribcage

Muscles Involved in Breathing Intercostal muscles are between ribs Intercostal muscles are between ribs

Inspiration diaphragm contracts and moves downward diaphragm contracts and moves downward intercostals move ribcage up and out intercostals move ribcage up and out the net result is an increase in lung volume and a decrease in pleural pressure the net result is an increase in lung volume and a decrease in pleural pressure Air moves into the lungs Air moves into the lungs

Expiration diaphragm relaxes and domes up diaphragm relaxes and domes up intercostal muscles relax intercostal muscles relax the net is result is a decrease in lung volume and an increase in pleural pressure the net is result is a decrease in lung volume and an increase in pleural pressure gas moves out gas moves out

Regulation of Breathing Chemoreceptors in medulla detect carbon dioxide Chemoreceptors in medulla detect carbon dioxide most important most important

Regulation of Breathing As carbon dioxide levels increase, nerves from brain send messages to respiratory muscles to increase breathing rate 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 CO 2 stays normal but oxygen is low ex) high altitude

Oxygen Transport Oxygen binds with hemoglobin to form oxyhemoglobin 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 Each Hb molecule can carry four oxygen molecules Hb + O 2 Hb(O 2 ) 4 Oxyhemoglobin

Oxyhemoglobin Dissociation Hemoglobin’s affinity for oxygen decreases as the acidity (carbon dioxide levels) increase Hemoglobin’s affinity for oxygen decreases as the acidity (carbon dioxide levels) increase Oxygen delivery increases to tissues in need Oxygen delivery increases to tissues in need

Carbon Dioxide Transport 20 times more soluble than oxygen 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 (HbCO 2 ) -competes with oxygen

Carbon Dioxide Transport 3. Most carbon dioxide(70%) combines with water in the plasma to form carbonic acid bicarbonate ions. 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 Reaction is catalysed by carbonic anhydrase enzyme

Carbon Monoxide Competes with oxygen for sites on hemoglobin – carboxyhemoglobin Competes with oxygen for sites on hemoglobin – carboxyhemoglobin 200X more affinity for Hb than oxygen 200X more affinity for Hb than oxygen

Carbon Monoxide Hemoglobin combined with CO is called carboxyhemoglobin Hemoglobin combined with CO is called carboxyhemoglobin Colorless, odorless Colorless, odorless Skin turns bright pink Skin turns bright pink

Nonrespiratory Air Movements Coughing and sneezing: Coughing and sneezing: contraction of diaphragm with sudden opening of glottis contraction of diaphragm with sudden opening of glottis Dislodges particles on membranes Dislodges particles on membranes

Nonrespiratory Air Movements Hiccuping: sudden diaphragmatic contractions Hiccuping: sudden diaphragmatic contractions Many causes; may be related to stomach activity Many causes; may be related to stomach activity

Nonrespiratory Air Movements Laughing: Laughing: epiglottis half-closes the larynx, so that air intake occurs irregularly, making you gasp epiglottis half-closes the larynx, so that air intake occurs irregularly, making you gasp A social signal – often initiated by group leaders A social signal – often initiated by group leaders

Nonrespiratory Air Movements Yawning: Yawning: Inspiration with stretching of facial muscles Inspiration with stretching of facial muscles Contagious, not due to gas levels in blood Contagious, not due to gas levels in blood Also is a social signal, wolves Also is a social signal, wolves

High Altitude Body adapts by: Short term – increasing force and rate of breathing Short term – increasing force and rate of breathing Increasing production of RBC’s using hormone erythropoeitin (EPO) Increasing production of RBC’s using hormone erythropoeitin (EPO) Increases lung capacity Increases lung capacity

Breathing Disorders

Hyperventilation Disorder caused by stress, etc. – lowered carbon dioxide levels due to overbreathing Disorder caused by stress, etc. – lowered carbon dioxide levels due to overbreathing Causes oxygen chemoreceptors to increase in sensitivity Causes oxygen chemoreceptors to increase in sensitivity Causes excessive breathing, which further decreases carbon dioxide levels- vicious cycle! 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 scuba diving, nitrogen dissolves in blood – due to increased pressure When ascending, the pressure drops and the nitrogen gas forms bubbles in blood vessels 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 Inflammation of the airways due to infection May be chronic, especially in smokers May be chronic, especially in smokers

Pneumonia Due to infection, lungs produce fluid Due to infection, lungs produce fluid Can cause ‘drowning’ Can cause ‘drowning’

Pneumothorax Collapsed lung 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