A&p Chapter 19 Physiology Of The Cardiovascular System

Front 1

Cardiac Cycle

Back 1

complete heartbeat consisting of diastole and systole of both atria and both ventricles

Front 2

Cardiac Output

Back 2

volume of blood pumped by one ventricle per minute

Front 3

Chemoreceptor Reflex

Back 3

functions as an emergency mechanism when hypoxia or hypercapnia endangers the stability of the internal environment

Front 4

Diastole

Back 4

relaxation of the heart (especially the ventricles), during which it fills with blood; opposite of systole

Front 5

Electrocardiogram

Back 5

graphic record of the heart's action potentials

Front 6

Minute Volume

Back 6

volume of blood circulating through the body per minute

Front 7

Pacemaker

Back 7

The sinoatrial node (SA node, or pacemaker) consists of hundreds of cells located in the right atrial wall near the opening of the superior vena cava

Front 8

Peripheral Resistance

Back 8

resistance to blood flow caused by friction of blood passing through blood vessels

Front 9

Pressoreflex

Back 9

baroreceptors in blood vessels, operating in feedback loops to maintain homeostasis of blood pressure; also called pressoreflex

Front 10

Stroke Volume

Back 10

amount of blood that is ejected from the ventricles of the heart with each beat

Front 11

Systole

Back 11

contraction of the heart muscle

Front 12

Vasoconstriction

Back 12

(vay-soh-kon-STRIK-shun) [vaso- vessel, -constrict- draw tight, -ion state of]

Front 13

Vasodilation

Back 13

(vay-soh-DYE-lay-shun) [vaso- vessel, -dilat- to widen, -ion state of]

Front 14

Venous Return

Back 14

refers to the amount of blood that is returned to the heart by way of the veins. Various factors influence venous return, including the reservoir function of veins, which occurs whenever blood pressure drops and the elasticity of the venous walls adapts the diameter of veins to the lower pressure, thus maintaining blood flow and venous return to the heart

Front 15

List the principal structures of the heart's conduction system.

Back 15

Sinoatrial node, atrioventricular node, AV bundle, and Purkinje system

Front 16

are the three types of deflection waves seen in a typical ECG?

Back 16

P wave, QRS complex, and T wave

Front 17

What event does each type of ECG wave represent?

Back 17

P wave: represents depolarization of the atria. QRS complex: represents depolarization of the ventricles. T wave: reflects repolarization of the ventricles

Front 18

Using Figure 19-8, describe the major events of the cardiac cycle.

Back 18

Atrial systole: emptying of blood out of the atria into the ventricles. Isovolumetric ventricular contraction: between the start of ventricular systole and the opening of the semilunar valves. Ejection: The semilunar valves open and blood is ejected from the heart. Isovolumetric ventricular relaxation: period between closure of the semilunar valves and opening of the atrioventricular valves. Passive ventricular filling: Return of venous blood increases intraatrial pressure until the atrioventricular valves are forced open and blood rushes into the relaxing ventricles

Front 19

As the ventricles contract, their volume remains constant for a period of time. Can you explain why the volume does not begin to decrease immediately?

Back 19

The abrupt inflow of blood that occurred immediately after opening of the atrioventricular valves is followed by a slow but continuous flow of venous blood into the atria and then through the open atrioventricular valves into the ventricles. This (diastasis) lasts about 0.2 second and is characterized by a gradual increase in ventricular pressure and volume.

Front 20

State the primary principle of circulation.

Back 20

Fluid always travels from an area of high pressure to an area of low pressure. Blood tends to move from an area of high average pressure at the beginning of the aorta toward the area of lowest pressure at the end of the venae cavae. Blood flow between any two points in the circulatory system can always be predicted by the pressure gradient

Front 21

Relate stroke volume and heart rate to cardiac output.

Back 21

Stroke volume x heart rate = Cardiac output

Front 22

8. If the amount of blood returned to the heart increases, what happens to the stroke volume? What principle explains this?

Back 22

An increase in the amount of blood to the heart will tend to increase stroke volume. Starling’s Law of the Heart

Front 23

How does the body use a pressoreflex to counteract an abnormal increase in heart rate? An abnormal decrease in heart rate?

Back 23

These pressoreflexes contain receptors (baroreceptors) sensitive to changes in pressure. Baroreceptors operate with integrators in the cardiac control centers in negative feedback loops that oppose changes in pressure by adjusting heart rate

Front 24

10. Peripheral resistance is affected by two major factors: blood viscosity and what else?

Back 24

Diameter of arterioles and capillaries

Front 25

the diameter of the arteries decreases, what effect does it have on peripheral resistance?

Back 25

A decrease in the diameter of the arteries will result in an increase in peripheral resistance

Front 26

In general, how do vasomotor pressoreflexes affect the flow of blood?

Back 26

Vasomotor reflexes detect changes in blood pressure and send the information back to the cardiac control center and the vasomotor center in the medulla. In response, these control centers alter the ratio between the sympathetic and parasympathetic output. If the pressure is too high, a dominance of parasympathetic impulses will reduce it by slowing heart rate, reducing stroke volume, and dilating blood “reservoir” vessels. If the pressure is too low, a dominance of sympathetic impulses will increase it by increasing heart rate and stroke volume and constricting reservoir vessels

Front 27

What is a chemoreflex? How do chemoreflexes affect the flow of blood?

Back 27

Chemoreflexes detect changes in carbon dioxide, decreases in oxygen, and decreases in pH. When changes are detected, this information is fed back to the cardiac control center and the vasomotor control center of the medulla, which, in turn, alter the ratio of parasympathetic and sympathetic output. When oxygen drops, carbon dioxide increases, and/or pH drops, a dominance of sympathetic impulses increases heart rate and stroke volume and constricts reservoir vessels, in response.

Front 28

What is meant by the term venous return?

Back 28

Venous return refers to the amount of blood that is returned to the heart by way of the veins.

Front 29

Briefly describe how the respiratory pump and skeletal muscle pump work.

Back 29

The respiratory pump operates by alternately decreasing thoracic pressure during inspiration and increasing pressure in the thorax during expiration. The skeletal muscle pump operates by the alternate increase and decrease in peripheral venous pressure that normally occur when the skeletal muscles are used for the activities of daily living.

Front 30

How does Starling's law of the capillaries explain capillary exchange?

Back 30

At the arterial end of a capillary, the outward driving force of blood pressure is larger than the inwardly directed force of osmosis—thus fluid moves out of the vessel. At the venous end of the capillary, the inward driving force of osmosis is greater than the outwardly directed force of hydrostatic pressure—thus fluid enters the vessel.

Front 31

What three hormonal mechanisms work together to regulate blood volume?

Back 31

Antidiuretic hormone, rennin-angiotensin and aldosterone mechanisms, and atrial natriuretic hormone.

Front 32

What is meant by the term minute volume?

Back 32

Minute volume is the volume of blood circulating through the body per minute.

Front 33

How is minute volume related to peripheral resistance?

Back 33

The volume of blood circulated per minute is directly related to mean arterial pressure minus central venous pressure and inversely related to resistance.

Front 34

What device is used in clinical settings to measure arterial blood pressure?

Back 34

Sphygmomanometer.

Front 35

Which is more important for assessing health—the systolic pressure or the diastolic pressure?

Back 35

Diastolic pressure.

Front 36

In which type of vessel is blood most likely to be flowing at a very slow rate—an artery, a capillary, or a vein?

Back 36

Capillaries

Front 37

Without being specific, where are pulse points normally located in the body?

Back 37

Radial artery, temporal artery, common carotid artery, facial artery, brachial artery, popliteal artery, posterior tibial artery, and dorsalis pedis artery

Front 38

Hemodynamics

Back 38

a term used to describe a colection of mechanism that influence the active and changing or dynamic circulation of blood

Front 39

Intrinsic rythym

Back 39

this means w/o any stimulation by nerve impulses from the brain and cord, they themselves initiate impluses at regular intervals.