Respiration

Pressure Gradients Concentration gradients for gases Gases diffuse down their pressure gradients Gases enter and leave the body by diffusing down pressure gradients across respiratory membranes

Atmospheric Pressure Pressure exerted by the weight of the air on objects on Earth’s surface At sea level = 760 mm Hg

Gas Exchange Respiration Pharynx (Throat) Epiglottis Larynx (Voice Box) Trachea (Windpipe) Pleural Membrane Bronchiole Alveoli Intercostal Muscle Diaphragm

Human Respiratory System

RESPIRATION The two systems that supply oxygen and eliminate carbon dioxide are the Cardiovascular System Respiratory System Failure of either of the two systems: disrupts homeostasis promotes cell death from oxygen starvation and waste product overflow

Respiration Exchange of gases between atmosphere, blood and cells Three types Pulmonary ventilation Inflow and outflow of air between atmosphere and lungs External (pulmonary) Respiration Exchange of gases between lungs and blood Internal Respiration Exchange of gases between blood and cells

Upper Respiratory Tract Nose – Openings – internal nares Nasal cavity divided by the nasal septum Functions of the Nose Interior structures warm, moisten and filters air Receives olfactory stimuli Provides a resonating chamber for speech sounds

Air Passage Air passes through nasal convolutions Mucous membrane lines the cavity and shelves traps particles More surface area for warming (from capillary beds) filtering moistening air

Pharynx Composed of skeletal muscle lined with mucous membrane Passageway for air and food Resonating chamber for speech sounds

Larynx Voice Box connects pharynx with trachea Thyroid forms front wall (triangular) Adam’s apple Epiglottis – (epi-above; glottis-tongue) leaf shaped covered by epithelium on top of larynx Stem attached to thyroid cartilage “leaf” free – trap door

Trachea Wall is lined with mucous membrane and supported by cartilage Pseudo stratified ciliated columnar epithelium makes up the inside of the trachea Goblet cells Mucous Traps inhaled particles Ciliated columnar cells Cilia Provide cleansing action to remove mucus with particles

Lungs Pleural membrane double layer that encloses and protects each lung Parietal pleura membrane outer layer is attached to the wall of the thoracic cavity and diaphragm Visceral pleura covers the lungs themselves Pleural cavity space between the two membranes contains fluid to reduce friction 13

Bronchi The trachea divides into a right and left primary bronchus The right is more vertical, shorter and wider than left more objects lodge here Structured like the trachea Incomplete rings of cartilage Lined with pseudo stratified ciliated epithelium

Secondary Bronchi One leads to each lobe of the lungs Right lung=3 lobes Left lung= 2 lobes Secondary bronchi break down to tertiary bronchi bronchioles terminal bronchioles

Alveolus Alveolus cup-shaped projection lined with epithelium Alveolar sacs two or more alveoli that share a common opening Gas exchange takes place here at the alveoli Arteriole and venule surround alveolus to form a capillary network Lungs contain 300 million alveoli large surface area

Oxygen Transport Most oxygen is carried bound to hemoglobin in red blood cells Hemoglobin has a great affinity for oxygen when it is at high partial pressure in pulmonary capillaries Lower affinity for oxygen in tissues, where partial pressure is low

Bicarbonate Formation + H+ CO2 + H2O H2CO3 carbonic acid HCO3– bicarbonate Most carbon dioxide is transported as bicarbonate Some binds to hemoglobin Small amount dissolves in blood

Breathing Moves air into and out of lungs Occurs in a cyclic pattern called the respiratory cycle One respiratory cycle consists of inhalation and exhalation 12 – 20 adults 15 – 30 children 25 – 50 infants

Inhalation Diaphragm flattens External intercostal muscles contract Volume of thoracic cavity increases Lungs expand Air flows down pressure gradient into lungs

Normal Passive Exhalation Muscles of inhalation relax Thoracic cavity recoils Lung volume decreases Air flows down pressure gradient and out of lungs

Active Exhalation Muscles in the abdomen and the internal intercostal muscles contract This decreases thoracic cavity volume more than passive exhalation A greater volume of air must flow out to equalize intrapulmonary pressure with atmospheric pressure

Respiratory Volumes Tidal volume Normal quiet breathing 500 ml Inspiratory reserve volume Forced inhalation 3100 ml Expiratory reserve volume Forced exhalation 1200 ml Residual volume Air left in lungs after expiratory volume

Respiratory Volumes inspiratory reserve volume tidal volume vital capacity total lung capacity expiratory reserve volume residual volume

Control of Breathing Medulla oblongata sets main rhythm centers in pons fine-tune it Magnitude of breathing depends on concentration of oxygen and H+ Brain detects H+ increases breathing Carotid bodies and aortic bodies detect drop in oxygen, increase breathing

pneumotaxic center apneustic center medullary respiratory center

food, water intake oxygen intake DIGESTIVE SYSTEM RESPIRATORY SYSTEM elimination of carbon dioxide nutrients, water, salts oxygen carbon dioxide CIRCULATORY SYSTEM URINARY SYSTEM water, solutes elimination of food residues rapid transport to and from all living cells elimination of excess water, salts, wastes

Carbon Monoxide (CO) Colorless, odorless gas Competes with oxygen for binding sites in hemoglobin Binding capacity is at least 200 times greater than oxygen’s Exposure impairs oxygen delivery

Impacts, Issues Video Up In Smoke

smoking In the US, about 3,000 teenagers take up smoking every day Just one cigarette immobilizes cilia that line airways of the lungs for hours, preventing them from sweeping away airborne pathogens and pollutants

smoking Filmy gunk from pathogens promotes: asthma attacks bronchitis colds Nicotine: constricts blood vessels raises blood pressure makes blood stickier and clots more likely Costs of smoking: clogged arteries heart attacks strokes lung cancer