Cardiac & Respiratory Dynamics

Vascular System

Carry blood away from heart Arteries  Arterioles  Capillaries Carry blood to heart Capillaries  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 mmHg Hypertension: >140/90 mmHg – Elevated blood pressure

Blood Erythrocytes (red blood cells) – Transport O 2 and CO 2 – Contain hemoglobin  bind O 2 and CO 2 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 HR Cardiac 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 (V E ) Inspiration + expiration Volume of air moved by lungs in 1 minute V E = V T 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 (VO 2 ) Increases with activity VO 2 max – maximal volume of oxygen that can be supplied to and consumed by body