LUNGS By the end of the chapter you should be able to: Label the internal structures of the lungs State the features of the alveoli which allow efficient gas exchange Explain the role of diffusion in gas exchange State the features of the capillary network that allow efficient gas exchange

GASEOUS EXCHANGE How are the structure and functions of the cardiovascular system and gaseous exchange linked? How are they affected by physical activity and our overall level of health?

GASEOUS EXCHANGE SYSTEM -links the circulatory system with the atmosphere clean warmed air enters during breathing surface area is maximized for the diffusion of O 2 and CO 2 between the blood and the atmosphere

GASEOUS EXCHANGE SYSTEM minimize the distance for diffusion maintain adequate gradients for this diffusion

BREATHING footprints breathing

THE LUNGS organs that allow gas exchange oxygen in / CO 2 out trachea - has rings of cartilage bronchi (bronchus) bronchioles alveoli (alveolus) computer animation

LUNGS -site of gaseous exchange between air and blood huge surface area in/out in the thoracic (chest) cavity surrounded by an airtight space between the pleural membranes

LUNGS small quantity of liquid in this area allows friction-free movement pleurisy – inflammation of the pleural membranes ventilated by the movement of the diaphragm and ribs

TRACHEA, BRONCHI, BRONCHIOLES lungs ventilated when air passes through a branching system of airways trachea – leads from the throat to the lungs bronchi (two) – at base of the trachea

TRACHEA, BRONCHI, BRONCHIOLES bronchus – subdivide and branch extensively forming bronchial tree cartilage – in the trachea and bronchi keep the airways open, air resistance low, and keeps them from collapsing or bursting as the air pressure changes during breathing

TRACHEA, BRONCHI, BRONCHIOLES trachea - C-shaped rings of cartilage bronchi – irregular blocks of cartilage small bronchioles lack cartilage – surrounded by smooth muscle which can contract or relax to adjust the diameter of the bronchioles allowing greater air flow to the alveoli during exercise

WARMING AND CLEANING THE AIR air warmed (to body temperature) and moistened (from evaporation from the lining) as it travels through the nose and trachea warming and moistening the air protects the inside of the lungs from desiccation (drying out)

WARMING AND CLEANING THE AIR hairs and mucus lining the nasal passages – remove particles larger than 5-10 μm (dust, pollen, bacteria, fungal spores, sand, and viruses) goblet cells – cells of the ciliated epithelium that produce mucus

WARMING AND CLEANING THE AIR upper part of each goblet cell is swollen with mucin droplets mucin – slimy solution of glycoproteins with many carbohydrates chains (makes it sticky and able to trap inhaled particles) rest of cell contains the nucleus and is quite slender like the stem of a goblet

WARMING AND CLEANING THE AIR mucus – also made by glands beneath the epithelium some pollutants – sulphur dioxide and nitrogen dioxide can dissolve in mucus to form acid and irritate the lining of the airways ciliated cells – between goblet cells

WARMING AND CLEANING THE AIR continual beating carries the carpet of mucus upwards towards the larynx at a speed of 1 cm/min mucus usually then swallowed and the pathogens are destroyed by stomach acids

WARMING AND CLEANING THE AIR macrophages – phagocytic white blood cells patrol the surfaces of the airways scavenging small particles such as bacteria and fine dust particles during infections - macrophages are joined by other phagocytic cells which leave the capillaries

ALVEOLI alveoli – at the end of the pathway between the atmosphere and bloodstream very thin epithelial lining surrounded by many blood capillaries carrying deoxygenated blood short distance – allows efficient diffusion

ALVEOLI elastic fibers - in alveolar walls stretch during breathing and recoil during expiration to help force air out fully expanded during exercise – surface area for diffusion increases

ALVEOLI (AIR SACS) provide large surface area for gas exchange one lung equivalent to a tennis court of surface area using alveoli footprints alveoli

air sac in lungs deoxygenated blood oxygenated blood body cells air in air out skool gas exchange

hyaline cartilage, mucous glands ciliated epithelium, goblet cells

ciliated, stratified appearance.

cartilage ring-like in appearance.

more smooth muscles as progress into bronchiole. -less mucus glands & cartilage

terminal respiratory bronchioles alveoli

macrophage in alveoli monkey lung

FEATURES OF ALVEOLI FOR EFFICIENT GAS EXCHANGE - SUMMARY large surface area to absorb oxygen. moist surface to allow oxygen to dissolve. Surfactant – reduces surface tension, keeps alveoli from recoiling and sticking together thin lining to allow easy diffusion of gases.. skool adaptation of alveoli

FEATURES OF CAPILLARIES FOR EFFICIENT GAS EXCHANGE dense network to carry CO 2 and O 2 Large surface area to transport gases Lining is one cell thick so gases can pass through quickly and easily.

AirwayNumberApprox. diameter CartilageGoble t cells Smooth muscle CiliaSite of gas exchang e trachea11.8 cmyes no bronchus21.2 cmyes no terminal bronchiole mmno yes no respiratory bronchiole mmno yesno alveolar duct9X μmno yes alveoli3X μmno yes

BREATHING RATE AND HEART RATE as body activity varies the rate cells need oxygen also varies rate of supply of oxygen to the cells is determined by the rate and depth of 1) breathing and 2) rate at which the heart pumps blood around the body breathing refreshes the air in the alveoli

BREATHING RATE AND DEPTH changing the depth and rate of breathing - maintains a constant concentration of O 2 and CO 2 no matter the level of activity at rest – ventilate about 6.0 dm 3 of air per minute

BREATHING RATE AND DEPTH about 0.35 dm 3 of new air enters the alveoli with each breath, only 1/7th of the total volume of air in the alveoli means large changes in the composition of alveolar air never occur impossible to empty the lungs completely even during forced exhalation

BREATHING RATE AND DEPTH residual volume - about 1.0 dm 3 of air remains in the alveoli and airways about 2.5 dm 3 of air remains in the lungs after breathing out normally breathing deeply – lungs can increase volume by as much as 3 dm 3 exercise increases the depth of breathing and breathing rate

BREATHING RATE AND DEPTH Tidal volume – volume in a single normal breath Vital capacity - volume breathed in after maximum expiration ventilation rate – total volume of air moved into lungs in one minute ventilation rate = tidal volume x breathing rate expressed as dm 3 min -1

BREATHING RATE AND DEPTH well trained athlete – achieve adequate ventilation by increasing the tidal volume with only a small increase in the breathing rate, training improves efficiency of the muscles involved with breathing

PULSE RATE ventricles contract – a surge of blood flows into the aorta and the pulmonary arteries under pressure stroke volume – volume of blood pumped out from each ventricle cardiac output – total volume pumped out per minute

PULSE RATE pulse – a blood surge distends the arteries (which contain elastic tissue) which stretch and subsequently recoil of aorta and arteries travels as a wave along all the arteries pulse rate – identical to the heart rate pulse measured – at wrist where the radial artery passes over bone or at the carotid artery in the neck resting pulse – an indication of fitness

PULSE RATE at rest – cardiac output is about 5 dm3 of blood every minute cardiac output – achieved by large stroke volume with a low pulse rate or small stroke volume with a high pulse more efficient – to pump slowly as the heart uses less energy than when pumping at a high rate

PULSE RATE physically fit – resting pulse low, stroke volume high, only a small increase in pulse is necessary to achieve the required blood supply – pulse rates return to resting level quickly after exercise

PULSE RATE normal range – adult resting pulse rates bpm average fit young adult – 70 bpm, falls with age pulse rate higher during/after exercise, after eating or smoking pulse rate lowers when sleeping

BLOOD PRESSURE systole – both ventricles contract left ventricle force oxygenated blood out of the heart to supply the body maximum arterial pressure – systolic pressure during active stroke, when blood leaves the heart through the aorta

BLOOD PRESSURE heart relaxes – left ventricular pressure falls, high pressure in the aorta closes the semilunar valve head of pressure – elastic recoil of the aorta and the main arteries provides a steady flow of blood in the arteries towards the capillaries diastolic pressure – minimum pressure in the arteries

BLOOD PRESSURE reflect resistance – of the small arteries and capillaries to blood flow and therefore the load against which the heart must work resistance high, so is the diastolic pressure – results from arteries not stretching well because they may have hardened

BLOOD PRESSURE sphygmomanometer – measures blood pressure systolic – 120 mm Hg (15 kPa) diastolic – 80 mm Hg (10.5 kPa) 120/80 – typical blood pressure

BLOOD PRESSURE BP – rise and fall during the day young adult – 110/75 60 years – 130/90 exercise – systolic 200 mm Hg, while diastolic rarely changes

HYPERTENSION hypertension - high systolic and diastolic blood pressures at rest no sharp distinction between ‘normal’ and ‘high’ blood pressure risk of stroke and coronary heart disease increases considerably with blood pressures in excess of 140/90 (hypertensive)

HYPERTENSION causes generally unknown short term hypertension - because of the contraction of smooth muscle in the walls of small arteries and arterioles may be as a result of increase in the concentration of the hormone noradrenaline which stimulates the arterioles to contract

HYPERTENSION contraction increases the resistance of the blood vessels and the heart works harder to force blood through the circulatory system long term hypertension – imposes a strain on the cardiovascular system can lead to heart failure when heart muscles weaken and are unable to pump properly

Category Blood pressure (mmHg) systolic diastolic optimal< 120< 80 normal< 130< 85 high normal hypertension> 140> 90

HYPERTENSION ‘ silent killer’ – no prior symptoms to give a warning of impending heart failure 90% of cases the exact cause of hypertension is unknown but linked to: excessive alcohol intake, smoking, obesity, too much salt in the diet, and genetic factors

LUNGS Can you? Label the internal structures of the lungs State the features of the alveoli which allow efficient gas exchange Explain the role of diffusion in gas exchange State the features of the capillary network that allow efficient gas exchange

[PA] Using Figure 9.3 as your microscope view, make a labeled drawing of each slide; a, b, & c and provide a description of the structure of the walls of the trachea, bronchioles, and alveoli with their associated blood vessels. Why is there a folded membrane in c? [9]