Heart and lungs Flashcards
Mediastinum
Lies between right and left pleura of lungs
Pericardium
outermost layer of heart
Myocardium
facilitates pumping action; contractile elements
Myocardial cells
automaticity, rhythmicity, conductivity
Pulmonary Circulation
delivers blood from heart to lungs & back to heart
Peripheral circulation
delivers blood from heart to body & back to heart
Arteries
large vessels that carry blood away from heart
Arterioles
small, branch arteries
Capillaries
smallest vessels; site of gas & nutrient exchange
Veins
vessels that carry blood toward heart
Venules
small veins that carry blood toward heart
Venous blood
blood returning to heart
Arterial blood
blood leaving heart and going to body or lungs
Tricuspid valve
right side
atrioventricular
Bicuspid/ mitral
left
atrioventricular
Pericardium
tough, membranous sac that encases heart
Systole
contraction phase; blood is pumped out of chamber
Diastole
relaxation phase; blood fills chamber
Autorhythmaticity
ability to initiate impulse for contraction at regular intervals
SA node
pacemaker of cardiac contraction
Atrioventricular node
delays impulse by 1/10 of second, allowing atria to contract before ventricles
Purkinje fibers
rapidly spreads impulse to contract throughout ventricles
Parasympathetic (crainosacral)nerve fibers:
decrease heart rate
Sympathetic (throcolumbar) nerve fibers
increase heart rate
Bradycardia
slow resting heart rate; often training-induced
Tachycardia
increase resting heart rate
Cardiac outut
stoke volume x heart rate
Syncytial contraction:
fibers contract simultaneously
Stroke volume
amount of blood pumped per contraction of ventricles
End-diastolic volume (EDV)
blood in ventricles at end of diastole
End-systolic volume (ESV):
blood in ventricles at end of systole
Ejection fraction (EF)
ratio of available blood to pumped blood
Sternum
Flat bone consisting of manubrium, body, xiphoid
Angle of Louis
The sternal angle– level of bifurcation of trachea into right and left main stem bronchi
Upper Respiratory Tract
Nose
Pharynx
Larynx
Lower Respiratory Tract
Tacheobronchial Tree – conducting airways Trachea Main stem/lobar bronchi Segmental/subsegmental bronchi Terminal respiratory (Acinar) units
Innervation of the lungs:
Receives afferent and efferent fibers from the vagus nerve, joined by branches from the sympathetic trunk and cardiac plexus.
Functions of respiratory system:
conducts air into and out of lungs exchange of gas between air and blood humidifies air warms air filters air
What are alveoli?
Saclike structures surrounded by capillaries in lungs
Attached to respiratory bronchioles
Function of alveoli?
Site of exchange of oxygen & carbon dioxide
Number of alveoli in lungs?
300 million
What membranes aid in diffusion?
Membrane of alveolar cells
Membrane of cells of capillary wall
Visceral (pulmonary) pleura
outer surface of lungs
Parietal pleura
inner surface of thoracic cavity & diaphragm
Pleural fluid
lubricating fluid between 2 membranes
Intrapleural pressure
pressure in pleural cavity between 2 membranes; less than atmospheric pressure
Pleural Sac
Double-layered membrane that encases each lung
Increase in volume of intrathoracic cavity:
Increases lung volume
Decreases intrapulmonic pressure
Causes air to rush into lungs (inspiration)
Decrease in volume of intrathoracic cavity
Decreases lung volume
Increases intrapulmonic pressure
Causes air to rush out of lungs (expiration)
What must inspiratory muscles do?
increase intrathoracic cavity volume
Function of diaphragm:
Flattens as it contracts
Puts in motion pressure changes that cause inspiration
Contraction moves abdominal contents forward & downward
Muscles that elevate ribs:
external intercostals, scalenes, sternocleidomastoid, pectoralis minor
Expiration:
No muscular effort needed at rest
Passive recoil of diaphragm & other muscles decreases intrathoracic cavity volume
During exercise or voluntary forced expiration:
accessory muscles of expiration contract, pulling ribs downward:
Internal intercostals
Rectus abdominis
Internal oblique muscles of abdominal wall
Formula for airflow
P1-P2/resistance
P1-P2 pressure difference between 2 areas
How can airflow be increases”
Amplifying pressure difference between 2 areas
Decreasing resistance to airflow
What is biggest factor affecting airflow at rest?
diameter of airway
Tidal volume
amount of air moved per breath
How is tidal volume calculated?
VE=Vt x f
VE is volume of air expired per minute
VT is tidal volume
f is breathing frequency per minute
Pulmonary ventilation
anatomical dead space + alveolar ventilation
Residual volume:
air left in lungs after max. exhalation