The Cardiovascular System

Mid Session Quiz -25%

• Next week• Will be on WebCT• From 5pm 21/8/07 5 pm 24/8/07• Multiple choice and matching• Covers all lecture, lab and reading materials from

weeks 1-5• Time limit = ½ hour• Grades and feedback will be released automatically

Design of lab

• Due in labs week 5 (Cut-off 24/8/07)

• Template on WebCT

• Resources see zali

• Submit– 1 hard copy per group– and email digital copy to Zali

Labs 1-5 Due by 31/8/07

• Submit lab book in labs week 6

• Cut-off date 31/8/07

Cardiovascular System

Chapter 10 of text

Major Cardiovascular Functions

Major Cardiovascular Functions

• Delivers oxygen to active tissues • Aerates blood returned to the lungs • Transports heat, a byproduct of cellular

metabolism, from the body’s core to the skin

• Delivers fuel nutrients to active tissues • Transports hormones, the body’s

chemical messengers

CV system

• Consists of;– Blood ~ 5L / 8% body mass– Heart- pump– Arteries- High pressure transport– Capillaries- Exchange vessels– Veins- Low pressure transport

Grey’s Anatomy

• Left Ventricular Assist Device (LVAD)

Peripheral VasculaturePeripheral Vasculature• Arteries

– Provides the high-pressure tubing that conducts oxygenated blood to the tissues

• Capillaries– Site of gas, nutrient,

and waste exchange• Veins

– Provides a large systemic blood reservoir and conducts deoxygenated blood back to the heart

Blood Pressure Blood Pressure

• Systolic blood pressure– Highest arterial pressure measured after left

ventricular contraction (systole)– e.g., 120 mm Hg

• Diastolic blood pressure– Lowest arterial pressure measured during

left ventricular relaxation (diastole)– e.g., 80 mm Hg

Heart Rate Regulation Heart Rate Regulation • Cardiac muscle

possesses intrinsic rhythmicity

• Without external stimuli, the adult heart would beat steadily between 50 and 80 times each minute

Regulation of HRRegulation of HR

• Sympathetic influence – Catecholamine (NE/E)– Results in tachycardia

• Parasympathetic influence– Acetylcholine – Results in bradycardia

• Cortical influence– Anticipatory heart rate

CV system during exercise

Acute Adaptations

Cardiovascular DynamicsCardiovascular Dynamics• Q = HR × SV (Fick

Equation)– Q: cardiac output– HR: heart rate– SV: stroke volume

Cardiac Output• At Rest

– Q = 5 L p/Min• Trained RHR = 50 bpm, SV = 71• Untrained RHR = 70 bpm, SV = 100

• During Exercise– Untrained- Q = 22 000 mL p/min, MHR = 195

» SV av 113 ml blood p/beat

– Trained- Q= 35 000 ml p/min, MHR = 195» SV av 179 ml blood p/beat

Q = HR × SV

Increases in Stroke Volume

• Increased ability to fill ventricles

• More forceful contraction to pump blood out

• Training adaptations– Increased blood volume– Reduced resistance to

blood flow

Cardiac output distribution

Oxygen Consumption

Oxygen Extraction

Muscle Blood Flow a-vO2

Cardiac Output

Stroke Volume Heart Rate

End Diastolic Volume

Venous Return

Muscle Contraction

Contractility

Cellular Respiration

Muscle Vascular Resistance

Figure 7.16

SympatheticStimulation

Oxygen transport

• 1 litre blood carries 200 ml oxygen

• During exercise– Q = 22L p /min

• = 4.4L oxygen per minute

• At rest– Q = 5L p/ min

• = 1 L oxygen per minute• 250 ml required at rest• Remainder- oxygen reserves

Cardiovascular Adaptations to Exercise

Chronic Adaptations

Pg 441-446 in text

Chronic Adaptations to Exercise

Cardiovascular adaptations to training are extremely important for improving endurance exercise performance, and preventing cardiovascular diseases.

The more important of these adaptations are, Size of heart ventricular volumes total blood volume

- plasma volume - red cell mass

systolic and diastolic blood pressures maximal stroke volume maximal cardiac output extraction of oxygen

Training Adaptations: Heart

• Eccentric hypertrophy – Slight thickening in left

ventricle walls– Increases left ventricular

cavity size

Therefore increases stroke

volume

Total Blood Volume

* Plasma volume

-4 training sessions can increase plasma volume by 20%

*Increased RBC

- Number of RBC increases, but due to increase in Plasma volume, concentration stays the same

Heart Rate

• Elite athletes have a lower heart rate relative to training intensity than sedentary people

Saltin, 1969

Endurance athletes

Sedentary college BEFORE 55 day aerobic training program

Sedentary college AFTER

Stroke Volume and Cardiac Output

• Exercise increases stroke volume during rest and exercise

• Slight decrease heart rate

• Increase in cardiac output comes from increased stroke volume

Blood Pressure

• Aerobic exercise reduces systolic and diastolic BP at rest and during exercise

• Particularly systolic– Caused by decrease in catecholamines

• Another reason for exercise to be prescribed for those with hypertension

• Resistance training not recommended due to acute high BP it causes

Oxygen Extraction

• Training increases quantity of O2 that can be extracted during exercise

Explain…

Why is there a difference in the Vo2 max of Jana Pittman and Kimberly Kim??

TRAINING!

What Chronic cardiovascular adaptations to training would have increased Vo2 max?

Exercise to VO2max Submaximal Steady State Exercise VO2max

Oxygen Delivery

Maximal Muscle Blood Flow

Maximal Cardiac Output

Maximal Stroke Volume

End Diastolic Volume

Muscle Capillary Density

Venous Return Ventricular Volume

Blood Volume

Plasma Volume Red Cell Mass

Training ForLong-Term Endurance

Sympathetic Stimulation

End Diastolic Volume

Venous Return

Blood Volume

Plasma Volume Red Cell Mass

Ventricular Volume

Stroke Volume

Heart Rate

Training ForLong-Term Endurance

Chronic Adaptations to Exercise

The more important of these adaptations are,Increased size of heart ventricular volumes total blood volume

- plasma volume - red cell mass

systolic and diastolic blood pressures maximal stroke volume maximal cardiac output extraction of oxygen

Factors Affecting Chronic adaptations

• Initial CV fitness• Training:

– Frequency- 3 x p/week• Only slightly higher gains for 4 or 5 times p/week

– Intensity• Most critical• Minimum is 130/ 140 bpm = (av) 50-55% Vo2 max/ 70% HR max • Higher = better

– Time • Or duration- 30 min is minimum

– Type• Specificity

Summary

• Need to know– Cardiac Structure and Function

• Veins/arteries/cappilaries

– Flow of blood through the heart – Acute adaptations to exercise– Chronic adaptations to exercise