CIRCULATORY AND RESPIRATORY SYSTEMS

Homeostasis- maintaining constant internal conditions under changing environmental conditions

Organ systems that supply tissues must have reserve capacity: increase or decrease supply when physiological demand changes

Supply of oxygen to metabolizing tissues integrated function of circulatory and respiratory systems

Integration of cardiac and respiratory function with demands of metabolizing muscles is performed by the autonomic nervous system

Blood pressure - systole vs. diastole - systole - maximum contraction - pressure generation - diastole - relaxation – refilling of chambers with venous blood

blood pressure

drops with distance

from heart

fluctuation in blood pressure

drops with distance

from heart – pressure damping

Increasing cardiac output - reserve capacity 1. increase stroke volume - volume pumped per

contraction 2. increase heart rate

Blood pressure is affected by: a. amount of heart contraction b. stroke volume c. peripheral resistance

- all circulatory routes not open simultaneously - more routes open lower resistance - autonomic nervous system controls heart

contractions and patterns of blood flow

For 2 subjects, measure:1) Resting heart rate, systolic, and diastolic blood

pressure 2) Exercise vigorously for 3-5 minutes3) Measure blood pressure and heart rate

immediately following exerciseExpected changes after exercise:Blood pressure: depends on fitness level- well-conditioned individuals: blood pressure may

decrease due to opening up more routes for blood flow to muscles – reduced peripheral resistance

- sedentary individuals: increased ventricle contraction increase blood pressure

Pulse rate: increase; amount varies based on fitness

RESPIRATORY RESERVES – ability to increase volume of gas exchanged when needed

Negative pressure breathers - aspiration mechanism- partial vacuum in lungs created by expanding volume of

chest cavity

Amount of expansion increases with demand:1) low level activity - diaphragm alone 2) moderate levels of activity - intercostal muscles expand,

compress rib cage3) extreme activity - abdominal, trunk

muscles move viscera up and down

Reserve capacity – two ways to increase gas exchange 1) increase tidal volume - volume of gas moved in and out of

lungs in each breathing cycle 2) increase breathing rateTidal volume - increases from rest exertion - increased inhalation – inspiratory reserve - increased exhalation – expiratory reserve

restingtidal

volume

inspiratory

reserve

expiratory

reserve

maximal tidal volume

The maximum tidal volume is called vital capacity - the greatest volume of air that can be moved in and out

with a single breathSpirometer - measures only expiration volumes; do not

inhale 3 measurements: A) inhale normally, then expel as much air as possible into

spirometer resting tidal volume + expiratory reserveB) exhale normally, then expel as much air as possible into

spirometer expiratory reserve onlyC) inhale maximally, then expel as much air as possible into

spirometer vital capacity = the sum of inspiratory reserve, expiratory reserve, and tidal volume

A – B = resting tidal volumeC – A = inspiratory reserve

Compare your vital capacity with average:Dubois chart – average (expected) vital capacity for man or

woman of given height and weightLook up your weight and height – chart gives you surface area

of body (in square meters) - multiply x 2 for women, x2.5 for men = expected vital

capacity in Liters (gender conversion factor) - calculate % difference from average - your measured vital

capacity vs. the expected average for someone of your sizeExample: - your vital capacity is 4.25L (measured with spirometer) - expected vital capacity is 4.0L (calculated from Dubois

chart)% difference = (4.25- 4.0)/ 4.0 x 100 = (0.25/4) x 100 =

+ 6.25%

RESPIRATORY RATE AND VOLUME Total volume of gas exchange = volume x

frequency of breathsRespiratory minute volume

= tidal volume x number of breaths/minute

Measure respiratory rate before and after vigorous exercise

Estimate:Resting minute volume = resting tidal volume x

resting respiration rateExertion minute volume = vital capacity x after

exercise respiration rate

TO DO:

1. Table 1 and 2. Collect BP and heart rate data before and after exercise for 2 members of your group.

2. Table 3 and 4. Measure respiratory volumes and % deviation from average for 2 individuals. Take the average of 3 readings for each measured volume.

3. Table 5. Respiratory minute volume, before and after exercise.

TO TURN IN NEXT WEEK:

1. Tables 1-5, and paragraph of interpretation of each.

What do these data tell you about the mechanics, function, or reserve capacity of the heart and respiratory system?

How does the autonomic nervous system affect these systems? Why?