KIN 411 I B - Exam #3

Why is the circulatory system considered a coupled unit?

The circulatory system has two units:

Respiratory System adds oxygen and removes carbon dioxide from the blood

Circulatory System delivers oxygenated blood and nutrients to tissues in accordance with their needs

What are the two major adjustments of blood flow during exercise?

Increased cardiac output

Redistribution of blood flow from inactive active muscle

Define and describe the purpose of the pulmonary circuit and systemic circuit.

Pulmonary Circuit

-Right side of the heart

-Pumps deoxygenated blood to the lungs via pulmonary arteries

-Returns oxygenated blood to the left side of the heart via pulmonary veins

Systemic Circuit

-Left side of the heart

-Pumps oxygenated blood to the whole body via arteries

-Returns deoxygenated blood to the right side of the heart via veins

Compare and contrast the structure of heart muscle and skeletal muscle.

Heart muscle

Contractile proteins: actin and myosin present

Shorter than skeletal muscle fibers and branching

Nuclei: Single

Z-discs: Present

Striated: Yes

Cellular junctions: Yes—interclated discs

Connective Tissue: Endomysium

Skeletal muscle

Contractile proteins: actin and myosin present

Elongated—no branching

Nuclei: Multiple

Z-discs: Present

Striated: Yes

Cellular junctions: No junctional complexes

Connective tissue: Epimysium, perimysium, and endomysium

What are the two phases of the cardiac cycle?

Systole

-Contraction phase

-Ejection of blood

Approximately 2/3 of blood is ejected from ventricles per beat

Diastole

-Relaxation phase

-Filling with blood

Define arterial blood pressure, pulse pressure, and mean arterial pressure.

Arterial Blood Pressure

Blood pressure is measured within the arteries and used as an indicator of health

Systolic Blood Pressure (SBP)

-Pressure generated during ventricular contraction

Diastolic Blood Pressure (DBP)

-Pressure in arteries during cardiac relaxation

Expressed as SBP/DBP

-Normal is 120/80 mmHg

Pulse Pressure

Difference between systolic and diastolic

PP= SBP - DBP

Mean Arterial Pressure (MAP)

Average pressure in the arteries during a cardiac cycle

MAP = DBP - 0.33(PP)

What are factors that influence arterial blood pressure?

Cardiac Output

-Amount of blood ejected from the heart

Total Vascular Resistance

-Sum of resistance to blood flow provided by all systemic vessels

How is blood pressure regulated?

Short-Term Regulation

-Sympathetic Nervous System (SNS)

-Baroreceptors in aorta and carotid arteries detect pressure changes and send impulses to the cardiovascular control

Increase in BP = decreased SNS activity

Decrease in BP = increased SNS activity

Long-Term Regulation

-Kidneys regulate blood pressure by controlling blood volume

Describe the process by which electrical activity moves through the heart.

1. Action potentials originate in the SA node and travel across the the wall of the atrium from the SA node to the AV node

2. Action potentials pass through the AV node and along the AV bundle

3. AV bundle decides into the right and left bundle branches, and action potentials descend to the apex of each ventricle along the bundle branches

4. Action potentials are carried by the Purkinje fibers from the bundle branches to the ventricular walls

Describe and be able to identify the p wave, QRS complex, and t wave on an electrocardiogram.

P Wave

-Atrial depolarization

QRS Complex

-Ventricular depolarization

-Atrial repolarization

T Wave

-Ventricular repolarization