Cardiac & Respiratory Dynamics

Vascular System

Carry blood away from heartArteries Arterioles Capillaries

Carry blood to heartCapillaries Venules Veins Large Veins

Venous Return• One-way valves

– Ensure blood goes back to the heart and not backwards

• Skeletal muscle pump– Low pressure in veins

skeletal contracts to increase pressure

• Thoracic pump– Difference in pressure between

2 cavities– Each breath taken, pressure in

chest cavity low, abdominal pressure increases

– Blood from abdominal to thoracic cavity

• Venoconstiction– Nervous system sends signal to

veins to slightly constrict

Cardiac Cycle• Diastole – phase of relaxation • Systole – phase of

contraction

Systolic blood pressure – measure in arteries during contraction (120 mm Hg)

Diastolic blood pressure – measure in arteries during contraction (80mm Hg)

Normal person: 120/80 mmHgHypertension: >140/90 mmHg– Elevated blood pressure

Blood

• Erythrocytes (red blood cells)– Transport O2 and CO2

– Contain hemoglobin bind O2 and CO2

• Leukocytes (white blood cells)– Protect body from diseases– Contain platelets blood clotting

Cardiovascular Dynamics

Cardiac Output

• Volume of blood pumped out of the left ventricle in 1 minute (L/min)

• Factors: stroke volume & heart rate

Q = SV x HRCardiac Output (L/min) Stroke

Volume (mL)

Heart Rate (beats/min)

• Stroke Volume (SV)– Amount of blood ejected from left ventricle in

single beat

SV = LVEDV – LVESV

• Heart Rate (HR)– Number of times hear beats in one minute

Maximum Heart Rate = 220 – age (years)

Stroke Volume

(mL)

Left Ventricular End-Systolic Volume (mL)

Left Ventricular Diastolic Volume (mL)

How do you increase Q?↑ Heart Rate↑ Stroke Volume

Increase SV or HR?

• Preferred way: ↑ stroke volume• Heart pushes more blood volume with each

pump in left ventricle• Heart can beat fewer times• Less stress on heart

• Athlete has lower heart rate and beats less than a sedentary person

Cardiovascular Training

• Cardiac output increase linearly with exercise intensity

• Body needs more oxygen = more blood is needed to be pumped to body

• Aerobic training• Increase in ventricular volume & thickness of

ventricular wall• ↑ ventricular volume = ↑stroke volume

Respiratory Dynamics

Pulmonary Ventilation• Rate and/or intensity of work being done = air in

and out of the body

Ventilation (VE)

• Inspiration + expiration• Volume of air moved by lungs in 1 minute

VE = VT x ƒ Ventilation (L/min)

Tidal Volume (L) – volume of air in each breath

Respiratory Frequency (breaths/min) – # of

breaths taken per minute

Oxygen Uptake

• Amount of oxygen consumed by body during cellular respiration

• Measure as volume of oxygen consumed in given time (VO2)

• Increases with activity

• VO2max – maximal volume of oxygen that can be supplied to and consumed by body