oxygenation, circulation, perfusion - fundamentals

describe oxygenation

movement of O2 from the air into the body at alveolar-capillary membrane by way of diffusion

describe circulation

heart acts as a pump pushing blood through the pulmonary and systemic circuits to support tissue perfusion

describe perfusion

delivery of oxygenated blood to capillaries/tissues for cellular use

what is ventilation?

breathing

describe inhalation/inspiration 

thorax(chest cavity) expands, so increased lung volume - air flows in - alveoli fill (decreased pressure)

external intercostal muscles push ribs up

diaphragm pushes down

describe expiration/exhalation

thorax recoils, returns to original size (increased pressure in cavity) - CO2 out

internal intercostal muscles / abdominal muscles

describe diffusion in ventilation

oxygen and carbon dioxide flow across the capillary/alveolar membrane

describe what the blood vessels do

maintain pressure and distribute flow to capillaries

how is ventilation effectiveness evaluated?

respiratory rate, chest rise, breath sounds, and work of breathing 

describe what gas exchange is

deoxygenated blood from the heart is carried to the lungs through the pulmonary artery

where does gas exchange occur

at the alveolar-capillary membrane

describe what the hemoglobin molecule in RBCs do

it drops off carbon dioxide for exhalation and picks up oxygen during inhalation

how does oxygenated blood return to the heart?

from the lungs by the pulmonary veins 

describe conductivity

generates an impulse

describe excitability

response to the impulse

describe the pathway in little detail of the impulse through the heart

SA node

AV node

bundle of his / AV bundle

R/L bundle branches

what does the impulse from the SA node do?

makes the atria contract 

what’s the rate of contraction from the SA node?

60-100 bpm

what does the impulse do when it travels through the AV node?

makes the ventricles contract

if the SA node stops working, what is next in line to generate impulses?

AV node

40-60bpm

what does electrical conduction produce?

the pulse

influences cardiac output

describe cardiac output

the amount of blood ejected form the heart in one minute

what Is the formula for CO

SV x HR

how is stroke volume impacted

after load

preload

describe preload 

the more volume in the ventricles, the more they stretch. the more they stretch, the more forcefully they contract 

describe after load

its the force/resistance that the ventricles need to overcome

describe diastole

ventricular relaxation

2/3 of cardiac cycle

describe valves during diastole

AV valves are open allowing blood to flow from atria into ventricles. initially blood flows rapidly due to the pressure in the atria

describe what happens at the end of diastole 

the atria contract to push out the last bit of blood 

describe systole

ventricular contraction 1/3 of cardiac cycle

blood has moved from the atria to ventricles, increasing pressure in the ventricles

describe the valves in systole

AV valves close, contributing to S1

the SL valves open and ventricles contract ejecting blood out

when pressure in ventricles fall below that of the aorta, SL close (S2)

what’re the physiological factors that influence oxygenation and perfusion?

age

obesity

activity 

what’re the lifestyle factors that influence oxygenation and perfusion?

smoking

stress

nutrition

substance abuse

describe age in oxygenation/perfusion

as you get older, contractile strength and elasticity of vessels decreases

describe obesity in oxygenation/perfusion

it impairs lung expansion. it increases cardiac workload

describe activity in oxygenation/perfusion

regular activity improves lung capacity and heart efficiency. 

sedentation reduces both 

describe smoking in oxygenation/perfusion

damages lungs and blood vessels, decreases airflow and oxygen transport

describe stress in oxygenation/perfusion

increased HR and vasoconstriction, more oxygen demand 

describe nutrition in oxygenation/perfusion

saturated fats increase risk for heart disease

describe substance abuse in oxygenation/perfusion

alcohol/drugs depress CNS impairing respiratory and cardiac function

what medications help in oxygenation/perfusion

bronchodilators, antihypertensives, diueretics - they improve oxygen and perfusion

what medications hinder in oxygenation/perfusion

opioids, sedatives, beta-blockers - may decrease respiratory drive or CO