The Cardiovascular System



The Cardiovascular System

The major parts of the cardiovascular system include:

•the heart

•arteries

•veins

•capillaries

Function of the CVS:

The role of blood in the CVS:

Anatomy of the heart:

Structure of Cardiac Muscle:

Blood flow through the heart and body:

Body

inf. and sup. vena cavae

rt. atrium

rt. ventricle

pulmonary artery

lungs

pulmonary vein

lf. atrium

lf. ventricle

aorta

Fetal Circulation:

Maternal blood supply-

umbilical veins- take O2 and nutrients to the fetus

½ of the blood goes to the liver to keep it developing

½ of the blood goes to the ductus venosus

( inferior vena cava (oxygenated and deoxygenated blood mix)

( right atrium ** a little blood goes to the pulmonary trunk

( blood that does get to the right ventricle will go out the pulmonary trunk and will be shunted to the aorta through the ductus arteriosus (at birth, this will stop functioning and become the ligamentum arteriosum

( foramen ovale (opening in the atrial septum) ( left atrium

( left ventricle ( aorta ( umbilical arteries

( waste is then carried to the umbilical cord ( mom

Blood Pressure

-the force that blood exerts against the inner walls of blood vessels (typically refers to pressure in the arteries)

Blood pressure changes in response to the phases of the cardiac cycle:

ventricular systole- period when the ventricles squeeze blood out into the pulmonary trunk (from the right ventricle) and the aorta (from the left ventricle)

--maximum pressure

----> measured as the systolic pressure

ventricular diastole- period when the ventricles relax

--lowest pressure

----> measured as the diastolic pressure

****Each contraction of the ventricles can be felt as the pulse

Factors that influence arterial blood pressure:

1. Heart Action-

2. Blood Volume-

3. Peripheral Resistance-

4. Blood Viscosity-

The Heart’s electrical conduction system:

-cardiac muscle cells will contract spontaneously even without stimulation from the nervous system

-to be efficient, the heart has to have a control system. There are 2 parts to this system:

1. Autonomic nerves-

- in times of stress, the sympathetic division of the ANS speeds up the heart in order to get more oxygen to the parts of the body that need it

-when you calm down, the parasympathetic division of the ANS slow the heart rate

2. The Intrinsic Conduction System (nodal system)-

Parts:

Sinoatrial node (SA node)- located in the right atrium

- a tiny cell mass that has the highest rate of depolarization

-

Atrioventricular node (AV node)- also in the right atrium

-

AV bundle, bundle branches and Purkinje fibers-

The Cardiac Cycle: the events of one complete heartbeat. Both atria and ventricles contract and then relax.

The Electrocardiogram (EKG or ECG)-

-the electrical changes are caused by the depolarization of the heart muscle.

-depolarization occurs when ions flow across the muscle cell membrane

Each wave in the EKG represents the depolarization or repolarization of the heart muscle:

P-wave-

QRS complex-

T-wave-

**the EKG does not show the repolarization of the atrial muscle because it happens when the ventricles contract and is therefore “covered up” by the QRS complex

-----------------------

tricuspid valve

pulmonary semilunar valve

bicuspid valve

aortic semilunar valve

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