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Flashcards in Heart and lungs Deck (61):
1

Mediastinum

Lies between right and left pleura of lungs

2

Pericardium

outermost layer of heart

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Myocardium

facilitates pumping action; contractile elements

4

Myocardial cells

automaticity, rhythmicity, conductivity

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Pulmonary Circulation

delivers blood from heart to lungs & back to heart

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Peripheral circulation

delivers blood from heart to body & back to heart

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Arteries

large vessels that carry blood away from heart

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Arterioles

small, branch arteries

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Capillaries

smallest vessels; site of gas & nutrient exchange

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Veins

vessels that carry blood toward heart

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Venules

small veins that carry blood toward heart

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Venous blood

blood returning to heart

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Arterial blood

blood leaving heart and going to body or lungs

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Tricuspid valve

right side
atrioventricular

15

Bicuspid/ mitral

left
atrioventricular

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Pericardium

tough, membranous sac that encases heart

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Systole

contraction phase; blood is pumped out of chamber

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Diastole

relaxation phase; blood fills chamber

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Autorhythmaticity

ability to initiate impulse for contraction at regular intervals

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SA node

pacemaker of cardiac contraction

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Atrioventricular node

delays impulse by 1/10 of second, allowing atria to contract before ventricles

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Purkinje fibers

rapidly spreads impulse to contract throughout ventricles

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Parasympathetic (crainosacral)nerve fibers:

decrease heart rate

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Sympathetic (throcolumbar) nerve fibers

increase heart rate

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Bradycardia

slow resting heart rate; often training-induced

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Tachycardia

increase resting heart rate

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Cardiac outut

stoke volume x heart rate

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Syncytial contraction:

fibers contract simultaneously

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Stroke volume

amount of blood pumped per contraction of ventricles

30

End-diastolic volume (EDV)

blood in ventricles at end of diastole

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End-systolic volume (ESV):

blood in ventricles at end of systole

32

Ejection fraction (EF)

ratio of available blood to pumped blood

33

Sternum

Flat bone consisting of manubrium, body, xiphoid

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Angle of Louis

The sternal angle– level of bifurcation of trachea into right and left main stem bronchi

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Upper Respiratory Tract

Nose
Pharynx
Larynx

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Lower Respiratory Tract

Tacheobronchial Tree – conducting airways
Trachea
Main stem/lobar bronchi
Segmental/subsegmental bronchi
Terminal respiratory (Acinar) units

37

Innervation of the lungs:

Receives afferent and efferent fibers from the vagus nerve, joined by branches from the sympathetic trunk and cardiac plexus.

38

Functions of respiratory system:

conducts air into and out of lungs
exchange of gas between air and blood
humidifies air
warms air
filters air

39

What are alveoli?

Saclike structures surrounded by capillaries in lungs
Attached to respiratory bronchioles

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Function of alveoli?

Site of exchange of oxygen & carbon dioxide

41

Number of alveoli in lungs?

300 million

42

What membranes aid in diffusion?

Membrane of alveolar cells
Membrane of cells of capillary wall

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Visceral (pulmonary) pleura

outer surface of lungs

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Parietal pleura

inner surface of thoracic cavity & diaphragm

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Pleural fluid

lubricating fluid between 2 membranes

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Intrapleural pressure

pressure in pleural cavity between 2 membranes; less than atmospheric pressure

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Pleural Sac

Double-layered membrane that encases each lung

48

Increase in volume of intrathoracic cavity:

Increases lung volume
Decreases intrapulmonic pressure
Causes air to rush into lungs (inspiration)

49

Decrease in volume of intrathoracic cavity

Decreases lung volume
Increases intrapulmonic pressure
Causes air to rush out of lungs (expiration)

50

What must inspiratory muscles do?

increase intrathoracic cavity volume

51

Function of diaphragm:

Flattens as it contracts
Puts in motion pressure changes that cause inspiration
Contraction moves abdominal contents forward & downward

52

Muscles that elevate ribs:

external intercostals, scalenes, sternocleidomastoid, pectoralis minor

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Expiration:

No muscular effort needed at rest
Passive recoil of diaphragm & other muscles decreases intrathoracic cavity volume

54

During exercise or voluntary forced expiration:

accessory muscles of expiration contract, pulling ribs downward:
Internal intercostals
Rectus abdominis
Internal oblique muscles of abdominal wall

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Formula for airflow

P1-P2/resistance
P1-P2 pressure difference between 2 areas

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How can airflow be increases"

Amplifying pressure difference between 2 areas
Decreasing resistance to airflow

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What is biggest factor affecting airflow at rest?

diameter of airway

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Tidal volume

amount of air moved per breath

59

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

60

Pulmonary ventilation

anatomical dead space + alveolar ventilation

61

Residual volume:

air left in lungs after max. exhalation