thorax/heart + lungs Flashcards
body cavities
thoracic cavity
- subdivided into right and left pleural cavities
- mediastinum
- pericardial cavity
pleural cavities
left and right which surround the lungs
mediastinum
central compartment of the thoracic cavity
pericardial cavity
surrounds the heart
boundaries of the thoracic cavity
bounded anteriorly and posteriorly by thoracic cage
- ribs
- sternum
- thoracic spine
- muscles
bounded inferiorly by diaphragm
- dome-shaped muscle that is inferior the heart and lungs
location of the heart
In the middle mediastinum, within the pericardial cavity
- directly posterior to the sternum
- between the lungs
- superior to the diaphragm
apex: points anteroinferiorly, and to the left
base: posterior and superior
functions of heart
4 chambered organ
- heart pumps blood throughout the body within a network of blood vessels
- chambers contract to pump blood
(flow is controlled by valves)
- blood is driven through two circuits:
pulmonary & systemic circuits
pulmonary circulation
- pumps deoxygenated (right side) from the heart to the lungs to become oxygenated
- pumps oxygenated blood (left side) from the lungs back to the heart
systemic circulation
- pumps oxygenated (left side) blood from the heart to the rest of the body
- returns deoxygenated (right side) blood back to the heart
pericardium
layered, fluid-filled sac that surrounds the heart
formed by the:
- outer fibrous pericardium
- inner serous pericardium
fibrous pericardium
- outer dense CT layer that surrounds the heart and the roots of the great vessels
- based of it is fused with the central tendon of the diaphragm
the central tendon
aponeurosis or flattened tendinous thickening of the diaphragm
functions of the fibrous pericardium
- anchors the heart in place
- provides protection
- prevents overextension of the heart
serous pericardium
the inner serous pericardium is formed by 2 layers
1. parietal pericardium- fused with the fibrous pericardium
2. visceral pericardium- adhered to the surface of the heart
pericardial cavity: potential space
adjacent structures are normally pressed together
- opposing layers of the visceral and parietal pericardium are in close contact
pericardial cavity/space
space between the visceral and parietal pericardium layers
- contains small amount of pericardial fluid
(acts as a lubricant, reducing friction between the opposing surfaces of the heart and the pericardium)
about the chambers of the heart
2 atria
- each atrium has a auricle
- form the base of heart (posteriorly)
2 ventricles
- form the apex of the heart
septa
chambers of the heart are separated by septa
- interatrial septum
(separates the right and left atria)
- interventricular septum
(separates the right and left ventricles)
external features of the heart
- atrioventricular groove
- anterior interventricular groove
- posterior interventricular groove
external features of the heart: great vessels
- superior vena cava (SVC)
- inferior vena cava (IVC)
- pulmonary trunk
- pulmonary arteries
- pulmonary veins
- aorta
coronary circulation: arterial supply (anterior)
a) right coronary artery (In atrioventricular groove)
b) left coronary artery
c) left anterior descending artery ( in anterior interventricular groove)
d) circumflex artery
coronary circulation: arterial supply (posterior)
a) right coronary artery
b) circumflex artery
c) posterior descending artery (in posterior interventricular groove)
coronary circulation: venous drainage (anterior)
a) great cardiac vein
b) small cardiac vein
coronary circulation: venous drainage (posterior)
a) small cardiac vein
b) middle cardiac vein
c) coronary sinus
- veins of the coronary circulation empty into the coronary sinus
superior and inferior vena cava
large veins that drain deoxygenated blood from the body into the right atrium of the heart
where does the coronary sinus drain into?
the right atrium
inferior vena cava
drains lower limbs, pelvis, abdominal viscera
superior vena cava
drains thorax, head, neck, upper limbs
right atrium
- pectinate muscles
- fossa ovalis: depression on the interatrial septum, embryological remnant of the foramen ovale
- SVC
- IVC
- coronary sinus
- tricuspid valve
fossa ovalis
foramen ovale functions during fetal development to allow blood to bypass the fetal lungs
- foramen ovale becomes the fossa ovalis after birth when the foramen closes
tricuspid valve
- one-way valve between the right atrium and the right vent.
- 3 cusps
right ventricle
- chordae tendinae: attach to valve cusps
- papillary muscles: anchor the chordae tendinae
- trabeculae carnea
(things features prevent prolapse of the valve during contraction of the ventricle) - tricuspid valve
- pulmonary valve
- pulmonary trunk
- pulmonary arteries (2)
pulmonary arteries
carry deoxygenated blood from the right ventricle of the heart to the lungs
(to become oxygenated)
pulmonary veins
once blood has become oxygenated, it enters the pulmonary veins
- carry oxygenated blood from the lungs to the left atrium
left atrium
- pectinate muscles
- pulmonary veins
- bicuspid/mitral valve
left ventricle
- chordae tendinea
- papillary muscles
- trabeculae carinae
- aorta
- bicuspid (mitral) valve
- aortic valve
aorta
large artery that carries oxygenated blood from the heart (left vent) to the body
arch of the aorta
branches supply head, neck, upper limbs
1. brachiocephalic trunk
2. left common carotid a.
3. left subscalvican a.
descending aorta
supplies blood to the thorax, abdomen, lower limbs
blood flow of the heart (the beginning with deoxygenated blood)
- deoxygenated blood from the body to the SVC or IVC
- enters right atrium
- tricuspid valve
- right ventricle
- pulmonary valve
- pulmonary trunk
- pulmonary arteries
- deoxygenated blood to the lungs
blood flow of the heart (oxygenated blood)
- oxygenated blood from lungs enter pulmonary veins
- left artium
- bicuspid valve
- left ventricle
- aortic valve
- arch of the aorta
- oxygenated blood to head, neck and upper limbs
- oxygenated blood to the thorax, abdomen and lower limbs (by descending aorta)
why is the wall thickness of the left ventricle larger
because the left needs to pump for the rest of the body so it needs more muscle
thoracic cavity: arterial supply
posterior thoracic wall:
- aorta continues as the descending thoracic aorta
- gives off the posterior intercostal arteries
(supply the posterior thoracic wall)
anterior thoracic wall:
- subclavian arteries give off the internal thoracic artery
- anterior intercostal arteries
thoracic cavity: venous drainage
- anterior and posterior intercostal veins drain into:
- azygous vein (right side)
- hemi-azygous and accessory hemiazygos veins (left side) then to azygous
innervation of thorcic cavity
intercostal nerves
- formed by the ventral rami of thoracic spinal nerves
- motor: innervate intercostal muscles
- sensory: innervate the overlying skin
mediastinum
central compartment of the thoracic cavity
- contains thoracic viscera outside of the lungs
- bordered laterally by the lungs and plural cavities
mediastinum borders
- bordered anteriorly by the sternum
- bordered inferiorly by the diaphragm
- bordered posteriorly by the thoracic vertebral column
divisions of the mediastinum
superior mediastinum
inferior mediastinum:
- anterior mediastinum
- middle mediastinum
- posterior mediastinum
superior mediastinum
- viscera: superior portions of the esophagus, trachea
- vessels: arch of the aorta and branches; SVC & brachiocephalic veins
anterior mediastinum
part of the inferior mediastinum
- between the sternum and heart
- contains the thymus gland
middle mediastinum
part of the inferior mediastinum
- contains the heart and roots of the great vessels
posterior mediastinum
part of the inferior mediastinum
- between the heart (pericardium) and vertebral column
- contains the thoracic aorta, inf. esophagus, azygous system
thymus gland
- lymphoid organ
- important site of white blood cell (T-cell) maturation
- hormone production
apertures of the diaphragm
IVC
esophagus
aorta
conducting portion
passage of air
1. nasal cavity
2. pharynx
3. larynx
4. trachea
5. primary bronchi
6. secondary bronchi
7.tertiary bronchi
8. bronchioles
9. terminal bronchioles
primary bronchi
c-shaped rings, trachealis muscle posteriorly
- bifurcates at the carina
- R. primary bronchus
- L. primary bronchus
secondary/lobar bronchi
3 lobar bronchi (right side)
2 lobar bronchi (left side)
tertiary/segmental bronchi
- 9-10 in each lung
- each supplies a bronchopulmonary segment
anatomy of lung
2 apex (for left and right)
2 bases (for L. R.)
cardiac notch (L)
anatomy of right lung
- superior lobe
- oblique fissure
- inferior lobe
- middle lobe
- horizontal fissure
anatomy of left lung
- superior lobe
- cardiac notch
- inferior lobe
- oblique fissure
lung hilum
- pulmonary artery
- pulmonary vein
- bronchus
pulmonary arteries and veins enter and exit the lungs via the respective hilum
pleural membranes
parietal pleura
visceral pleura
parietal pleura
covers the inner surface of the thoracic wall and extends over diaphragm and mediastinum
visceral pleura
covers the outer surface of the lungs; extends into the fissures between lobes
pleural cavity/space
- potential space between the visceral and parietal pleura
- contains a small amount of pleural fluid
respiratory portion
- respiratory bronchioles
- alveolar ducts
- alveoli & alveolar sacs
alveoli & alveolar sacs
- each alveolar duct ends in an expanded region known as an alveolar sac
- alveolar sacs are made up of clusters of alveoli
- alveoli are the main sites of gas exchange
- gives lungs their spongy appearance
alveoli
- primary sites of gas exchange:
O2–> into bloodstream
CO2–> out of bloodstream - extensive capillary network surrounds each alveolus
- elastic fibers surround alveoli which facilitate stretch and recoil during gas exchange
what does branches of the pulmonary arteries and veins surround?
the alveoli of the lungs to facilitate gas exchange
bronchial arteries
carry oxygenated blood to the lungs and bronchi
bronchial veins
carry deoxygenated blood from the lungs and bronchi
- drain into the azygous system
innervate of the lungs
- sympathetic: bronchodilation
- parasympathetic: bronchoconstriction
innervate of the diagram
phrenic nerve provides motor innervation
pressure and volume
they are inversely related
inspiration
- as lung volume increases, pressure in the lungs decreases relative to atmospheric pressure
- air is drawn into the lungs
expiration
- as lung volume decreases, pressure in the lungs increases relative to atmospheric pressure
- air flows out of the lungs
mechanism of breathing: inspiration
- expansion of the chest cavity in 3 dimensions
primary muscle: diaphragm (contracts and flattens) - secondary muscles: external intercostal muscles (elevate ribs)
- decreased pressure pull air into the lungs
mechanism of breathing: expiration
primary: diaphragm relaxes, structures return to pre-inspiratory positions
secondary: internal intercostal muscles depress ribs
- elastic recoil of alveoli
- decreases thoracic and lung volume
- increased pressure expels air from the lungs
gas exchange & respiratory membrane
exchange of O2 and CO2 between the lungs and the blood takes place by diffusion across the alveolar and capillary walls
- O2 and Co2 move between alveolar air and blood via down a diffusion gradient
when does O2 flow
enters the respiratory portion (inspiration)
- O2 diffuses from the alveolus across the respiratory membrane into the capillary, where it can bind to RBCs and transported around the body
when does CO2 flow
CO2 diffuses across the respiratory membrane into the alveolus
- CO2 is expelled via expiration
