Chapter 8 Unit Test Flashcards
Function of the Circulatory System
- One loop delivers blood to the body (oxygenated)
- The other delivers blood to the lungs (deoxygenated)
Function of blood carried by the circulatory system
- transports oxygen to the body cells
- transports nutrients from the digestive system to body cells
- transports hormones to body cells
- transports waste from the body cells to excretory organs
- distributes body heat
- maintains constant pH in tissue fluids
- prevents infections
Systemic System
- carries blood throughout the body(except the heart and lungs)
- brings nutrients and oxygen to the body tissues
- removes carbon dioxide and other wastes
Pulmonary System
- carries blood from the right side of the heart to the lungs where carbon dioxide is eliminated and oxygen is picked up
- blood returns to the left side of the heart where it is distributed via the systemic system
Coronary System
- provides blood to the heart
- the heart receives its own supply of blood from the coronary arteries
- two major coronary arteries branch off from the aorta
- These arteries and their branches supply all parts of the heart muscle with blood
Layers of the Heart
There are three layers of the heart. They are called; pericardium, Myocardium and the Endocardium
Pericardium
a thin closed sac surrounding the heart and the bases of the vessels that enter and leave the heart. It is filled with a clear slippery fluid that reduces friction caused by heart contractions
Myocardium
The middle layer, it is the thickest part of the wall and is composed mostly of cardiac muscle cells
Endocardium
inner layer that forms the lining of the heart chambers
How many chambers are in the human hearts
there are 4 chambers. The top half is the atria, the bottom half if the ventricles.
The Atria
it acts as holding chambers for blood entering the heart from the systemic of pulmonary circulatory systems
The Ventricles
they are stronger and are more muscular, they pump blood to the tissues in the body
Human heart has 4 valves
valves ensure blood moves in one direction.
As the heart muscle contracts and relaxes, the valves open and shut
Atrioventricular Valves (A-V Valves)
they are the valves between the atria and the ventricles on the left and right side of the heart consisting of two or three flaps of tissue that are anchored to the inner walls of the ventricles by the chordae tendineae
Tricuspid Valve
the A-V valve on the right side of the heart, between the right ventricle and atrium ( 3 flaps of tissue)
Bicuspid Valve
the A-V valve on the left side of the heart (2 flaps of tissue)
Semilunar Valves
found in the areas in which the blood vessels attach to the ventricles at the pulmonary artery and aorta.
consists of three flaps of tissue resembling half moons
How does blood return from our heart to our feet
- one way valves
- skeletal muscles squeeze blood upward
Arteries
- Carry blood AWAY from the heart to body tissues
-thick muscular walls with three distinct layers of tissue
- stretch to accommodate blood rushing in
- blood flows due to elasticity of the artery walls
- arteries of various sizes branch around the entire body
- the largest artery is the aorta found in the heart
- smaller sized arteries are called arterioles whose diameter is regulated by nerves
- arterioles branch into capillaries
Veins
- carry blood back to the heart
- capillaries merge and form venules, which then merge into veins
- walls are thinner and weaker than the walls of arteries
- the pressure of blood is less than it is in the arteries so veins need valves to move the blood back to the heart
- contractions of the skeletal muscles surrounding the veins also aid in the pushing of blood back to the heart
- veins start off small and converge with other veins, forming larger and larger vessels
- the largest veins are the superior and inferior vena cava found in the heart
Capillaries
- forms and extensive gas exchange system
- have thin walls through which nutrients and wastes can pass
- provide a site of exchange between the blood and the tissue fluid surrounding the cells of the body
- permeable to many substances: O2, CO2, water soluble ions, vitamins and some proteins
- oxygen diffuses from the blood through the capillary walls to the surrounding tissue, and carbon dioxide and other wastes move in the opposite direction
- work through the processes of endocytosis, exocytosis, osmosis and diffusion
- one cell layer thick – easy to destroy (high blood pressure can burst a capillary, even a bruise is evidence of ruptured capillaries)
Vasoconstriction
is the narrowing of blood vessels due to the contraction of smooth muscle fibres in the arterioles.
Ex. when we turn white in fright, skin blood vessels constrict so that more blood is supplied to the muscles
Vasodilation
is the widening of blood vessels resulting in more blood entering the tissue area, caused by a relaxation of the muscle fibres in the blood vessels
Ex. blushing is a vasodilation of skin blood vessels
The pathway of blood
Right atrium - tricuspid valve - right ventricle - pulmonary valve - pulmonary arteries - lungs - pulmonary veins - left atrium - mitral valve - left ventricle - aortic valve - aorta - foot - inferior vena cava
Normal resting heart rate
60 to 100 bpm
Stethoscope
instrument to listen and measure heart sounds
Heart beat
the SA node functions as the heart’s pacemaker and initiates the heart beat causing both Atria to contract
the AV node delays the impulse so that the atria can empty. the impulse travels through the bundle of his and the purkinje fibers causing both ventricles to contract
contraction of heart muscle is known as systole while relaxation of heart muscle is diastole
the sound of a heart beat are caused by closing of the heart valves
ECG - electrocardiogram
a recording of the electrical events (changes) during a cardiac cycle ; this is the same thing as an EKG
Arrhythmia
irregular heart rate
Bradycardia
slow heart rate
Tachycardia
fast heart rate
Defibrillator
- common treatment for life-threatening cardiac arrhythmia
- The device shocks the heart and allows it to re-establish its normal rhythm
- The device can also be used to start a heart that has stopped.
Sphygmomanometer
blood pressure of the brachial artery (major artery of the arm)
shuts off the flow of blood to the brachial artery by increasing air in the cuff around the arm
Systolic pressure
read at the point where a heartbeat sound is heard after the cuff is slowly drained of air as the blood flows back into the brachial artery during ventricular contraction