16- Cardiovascular Physiology: circuitry and blood

Heart

A muscular organ comprised of cardiac tissue that contracts and relaxes rhythmically to pump blood

How much blood does the heart do at rest?

-Pumps approximately 5 liters (L) of blood per minute

-During short periods of exercise, the amount of pumped blood increases 7x

What is the orientation of the heart?

-Heart base = Proximal (near) to the head

-Heart apex = Distal (away) from the head

How many chambers does each side of the heart have?

Two

-Atrium= top chamber

-Ventricle = Lower chamber

What do the atrioventricular valves do?

Allow unidirectional blood flow from the atrium to the ventricle

-Tricuspid (Three cusps)

-Bicuspid (Two cusps)

What do the semilunar valves do?

-Allow unidirectional blood flow from the ventricle to the artery

-Aortic (Blood enters the Aorta)

-Pulmonary (Blood enters the Pulmonary arteries)

What is the primary function of the cardiovascular system?

To deliver blood (nutrients) to the tissues and remove waste products from the cells.

-Arteries = Carry blood from the heart to the tissues

-Veins = Carry blood from the tissues back to the heart

What circulation is the right side of the heart responsible for?

Pulmonary circulation

What circulation is the left side of the heart responsible for?

Systemic circulation

Cardiac output

the rate at which blood is pumped form either ventricle

Venous Return

The rate at which blood is returned to the atria

What fills the left ventricle?

Oxygenated blood

How does oxygenated blood return to the left atrium?

Via the pulmonary vein

How does blood flow from the left atrium to the left ventricle?

Through the bicuspid (mitral) valve

What happens when blood is ejected from the left ventricle?

It enters the aorta

What causes the pressure in the left ventricle to increase?

Left ventricle contraction

How does blood leave the left ventricle?

Through the aortic valve

How is cardiac output distributed among various organs?

Via sets of parallel arteries

What percentage of cardiac output goes to the brain?

15%

What percentage of cardiac output goes to the heart?

5%

What percentage of cardiac output goes to the kidneys?

25%

What percentage of cardiac output goes to the gastrointestinal organs?

25%

What percentage of cardiac output goes to skeletal muscle?

25%

What percentage of cardiac output goes to the integumentary system?

5%

Due to the parallel arrangement of organ systems, wat must the total systemic blood flow equal?

The cardiac output

What type of blood leaves the organs?

Venous blood

What does venous blood contain?

Waste products from metabolism

Where does venous blood collect before emptying into the vena cava?

In larger and larger veins

What equals the venous return to the right atrium in steady state?

Cardiac output from the left ventricle

What fills the right ventricle?

Mixed venous blood

How does blood flow from the right atrium to the right ventricle?

Through the tricuspid valve

What happens when blood is ejected from the right ventricle?

It enters the pulmonary artery

What pushes blood through the pulmonic valve into the pulmonary artery?

Right ventricle contraction

Where does the pulmonary artery carry blood?

To the lungs

How is blood flow from the lungs returned to the heart?

Via the pulmonary vein

What returns to the left atrium to begin a new cycle?

Oxygenated blood

Blood

Fluid form of connective tissue

-Consists of cells and cell fragments surrounded by a liquid matric

What does the amount of blood in the body depend on?

Depends of size and sex

-Females = 4 - 5 liters total blood volume

-Males = 5 - 6 liters total blood volume

What percentage of total body weight does blood make up?

7-9%

What are the functions of blood?

Transportation, Regulation, and Protection

Transportation

-Blood transports gases, nutrients and waste products throughout the body

-Blood transports processed molecules from one part of the body to the next for further use or processing

-Blood transports regulatory molecules (hormones & enzymes) to target tissues throughout the body

Regulation

-Blood regulates different levels in body hierarchy to help maintain homeostasis

-Blood buffers ensure that pH levels are kept within normal limits (between 7.35 and 7.45)

-Blood helps regulate body temperature by absorbing heat from skeletal muscle/releasing heat through skin

-Blood can take or give up more fluid to help regulate fluid balance in the body

Protection

-Blood helps protect the body from invasion and infection by pathogens and toxins

-Specialized leukocytes and antibodies function to prevent infection

-Clot formation: Provides protection against excessive blood loss when blood vessels are damaged

What are the components of blood?

Formed elements such as cells and cell fragments and plasma.

-About 95% of the formed elements are RBCs; 5% are leukocytes and platelets

Plasma

the liquid component of blood

-Pale yellow fluid

-Consists of 91% water, 7% proteins, & 2% ions, nutrients, gasses, and waste products

-Plasma proteins: Albumin, globulins, & fibrinogen

Hemostasis

the prevention of blood loss

How is hemostasis accomplished?

-When the inner wall of a vessel is damaged, an underlying collagen fiber becomes exposed

-Platelets in the blood begin to attach to the damaged site

-The attached platelets release several chemicals that draw more platelets, creating a platelet plug