Cardiovascular System

The cardiovascular system

Unit 15 Synopsis

Cardiovascular System Functions

Functions

Wordbytes

A-, An-

without

Anti-

Against

cardio-

Heart

-cyte

cell

-emia

blood

erythro-

red

ferr-

iron

heme-,

blood

Hemo-

Blood

leuko-

white

phlebo-

vein

-poiesis

formation

Thromb-

clot

Ven-

Vein

Angio-

blood vessel

Pulmo-

lung

Brady-

slow

Tachy-

fast

Vaso-

vessel

Blood

Blood is a connective tissue that is made of cellular elements and an extracellular matrix.

Formed elements include: erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets)

The extracellular matrix is called plasma.

Blood functions to deliver oxygen and nutrients to cells and remove waste from somatic cells, immunity, distribution of heat, and maintenance of homeostasis.

Composition of blood:

45% erythrocytes

<1% buffy coat that includes leukocytes and thrombocytes

55% plasma

Blood makes up approximately 8% of the adult body weight

Plasma proteins:

Albumin: the most abundant protein; functions to transport fatty acids and steroid hormones. It is the most significant contributor to osmotic pressure of blood.

Globulins: alpha, beta, and gamma classifications

Alpha and beta transport iron, lipid, and fat soluble vitamins (ADEK)

Gamma globulins serve as immunity. Also known as immunoglobulins or antibodies

Fibrinogen

Essential for blood clotting

Blood Cells

Erythrocytes:

Have a biconcave shape

Lack a nucleus, this allows extra space to carry more oxygen

Contains a hemoglobin protein

Large protein molecule made of 4 polypeptide chains containing a heme group that have iron

Leukocytes

Used in immunity

Several types:

Neutrophils: Immune defense

Eosinophils: Parasitic defense

Basophils: Inflammatory response

Monocyte: immune surveillance

B-lymphocyte: antibody production

T-lymphocyte: cellular immune response

Thrombocytes:

Platelets are not true cells, but rather cell fragments that are essential to hemostasis.

Hemostasis

Blood Clotting Cascade

Blood Typing - ABO classification

Universal Donor: O-

Universal Receiver: AB+

Vessels

Arteries: blood vessels that carry blood away from the heart

Thick, muscular, elastic walls that are able to cope with the high pressures generated by a heartbeat

Veins: blood vessels that bring blood back to the heart

Thinner, expandable walls and one-way valves that prevent backflow

Capillaries: Oxygen diffuses out of these minute, thin-walled vessels to supply body cells, while waste carbon dioxide diffuses in. Thin enough to allow only a single cell to pass at a time.

Heart Anatomy

Blood Flow through the Heart

Right Atrium

through the tricuspid valve

Right Ventricle

through the pulmonary valve

Pulmonary trunk and pulmonary arteries

Pulmonary capillaries in lungs, where blood loses CO2 and gains O2

Pulmonary veins

Left Atrium

Bicuspid valve (Mitral)

Left Ventricle

Aortic valve

Aorta and systemic arteries

Systemic capillaries

Systemic veins

Superior and inferior vena cava

**Back to start**

Cardiac Cycle

Sinoatrial Node (SA node)

-Pacemaker that sets the rhythm of electrical excitation causes contractions

-Spontaneous depolarization

Cardiac Cycle

Describes the physiological events during a single heartbeat

Atrial Systole

Atria are contracting

Ventricles are relaxing

P wave represents the depolarization of the SA node causing atrial depolarization which causes atrial systole (contraction)

The contraction exerts pressure on blood which in turn forces the atrioventricular (AV - tricuspid and mitral) valves to open

QRS complex marks the onset of ventricular depolarization

Ventricular Systole

Ventricles are contracting

Atrial diastole (relaxation)

Ventricular depolarization leads to ventricular systole

Pressure builds up in ventricles, pushes blood against AV valves, closing them.

This closing makes the "lub"

Continued contractions increase pressure until it opens the semilunar valves (SL - Aortic and pulmonary)

Blood enters the aorta and the pulmonary trunk

T wave in EKG marks the onset of ventricular repolarization

Relaxation Phase

Both atria and ventricles are relaxed (in diastole)

When the ventricular pressure falls below the atrial pressure, the AV valves open, allowing ventricular filling to occur.

The closing of the SL valves is the "dub" sound