Cardiovascular System Flashcards
Circulatory system
-responsible for the internal transport of substances to and from the cells
-usually consist of the following three parts:
- blood: composed of water, solutes and other elements in a fluid connective tissue
-blood vessels: tubules of different sizes that transport blood
-heart: muscular pump providing the pressure necessary to keep blood flowing
Circulatory systems
-Can be open or closed
-most animals have closed systems, where the heart and blood vessels are continuously connected
-as the blood moves through the system from larger tubules to smaller ones, the rate slows down
-the flow of blood in the capillary beds, the smallest tubules, is quite slow
-a supplementary system, the lymph vascular system, cleans of excess fluids ands proteins and returns them to the circulatory system
Arterial and Venous systems
Arteries, arterioles, venules, veins
The walls of all blood vessels except for capillaries consist of three layers:
- the innermost tunica intima
-the tunica media consisting of smooth muscle cells and elastic fibers
-the outermost tunica adventitia
[vessel, structure, function]
Vessel: Elastic arteries
Structure:
-includes the aorta and major branches
-Tunica media has more elastin than any other vessels
-largest vessels in the arterial system
Function:
-Stretch when blood is forced out of the heart, and recoil under low pressure
[vessel, structure, function]
Vessel: muscular arteries
Structure:
-Includes the arteries branch off of the elastic arteries
-Tunica media has a higher proportion of smooth muscle cells, and fewer elastic fibers as compared to elastic arteries
Function:
-Regulate blood flow by vasoconstriction/vasodilation
[vessel, structure, function]
Vessel: Arterioles
Structure:
-Tiny vessels that lead to the capillary beds
-Tunica media is thin but composed almost entirely of smooth muscle cells
Function:
-Primary vessels involved in vasoconstriction/vasodilation
-control blood flow to capillaries
[vessel, structure, function]
Vessel: Venules
Structure:
-tiny vessels that exit the capillary beds
-thin, porous walls
-few muscle cells and elastic fibers
Function:
Empty blood into larger veins
[vessel, structure, function]
Vessel: Veins
Structure:
-thin tunica media and tunica intima
-wide lumen
-valves prevent back flow of blood
Function:
-carry blood back to the heart
Blood
-Helps maintain a healthy internal environment in animals by carrying raw materials to cells and removing waste products
-helps stabilize internal pH and hosts various kinds of infection fighters
-adult human has about 5 quarts of blood
-blood is composed of red and white blood cells, platelets and plasma
-plasma constitutes over half of the blood volume—it is mostly water and serves as a solvent
-plasma contains plasma proteins, ions, glucose, amino acids, hormones and dissolved gases
-red blood cells transport oxygen to cells
-red blood cells form in the bone marrow and can live for about four months
-the cells are constantly being replaced by fresh ones, keeping the total number relatively stable
-white blood cells defend the body against infection and remove various wastes
-the type of white blood cells include lymphocytes, neutrophils, monocytes, eosinophils, and basophils -platelets are fragments of stem cells and serve an important function in blood clotting
Heart
-Muscular pump made of cardiac muscle tissue
-four chambers, each half contains both an atrium and a ventricle and the halves are separated by a valve known as the AV valve located between the ventricle and the artery leading away from the heart
-valves keep blood moving in a single-direction and prevent any backwash into the chambers
-heart has its own circulatory system, with its own coronary arteries
-heart functions by contracting and relaxing
-atrial contraction fills the ventricles and ventricular contraction empties them, forcing circulation
-the sequence is called cardiac cycle
-cardiac muscles are attached to each other and signals for contraction spread rapidly
-a complex electrical system controls the heartbeat as cardiac muscle cells produce and conduct electric signals
-these muscles are said to be self-exciting, needing no external stimuli
Cardiac cycle
atrial contraction fills the ventricles and ventricular contraction empties them, forcing circulation
-the sequence is called cardiac cycle
Cardiac cycle
-Consists of diastole and systole phases which can be further divided into the first and second phases to describe the events of the right and left sides of the heart
-these events are simultaneously occurring
-during the first diastole phase, blood flows through the superior and inferior venae cavae
-because the heart is relaxed, blood flows passively from the atrium through the open atrioventricular valve (tricuspid valve) to the right ventricle
-the sinoatrial node (SA node), the cardiac pacemaker, located in the wall of the right atrium, generates electrical signals, which are carried by the Purkinje fibers to the rest of the atrium, stimulating it to contract and fill the right ventricle with blood
-the impulse from the SA node is transmitted to the ventricle through the atrioventricular node
(AV node), signaling the right ventricle to contract and initiating the first systole phase
-the tricuspid valve closes, and the pulmonary semilunar valve opens
-blood is pumped out the pulmonary arteries to the lungs
-blood returning from the lungs fills the left atrium as part of the second diastole phase
-the SA node triggers the mitral valve to open and blood fills the left ventricle
-during the second systole phase the mitral valve closes and the aortic semilunar valve opens
-the left ventricle contracts, and blood is pumped out of the aorta to the rest of the body
[Types of circulation]
Circulatory system
Includes coronary circulation, pulmonary circulation, and systemic circulation
[Types of circulation]
Coronary circulation
-Flow of blood to the heart tissue blood enters the coronary arteries, which branch off the aorta, supplying major arteries, which enter the heart with oxygenated blood
-the deoxygenated blood returns to the right atrium to the cardiac veins, which empties into the coronary sinus
[the lymphatic system]
Spleen
-the spleen filters blood stores of red blood cells and macrophages
-the main functions of the spleen are to filter unwanted materials from the blood (including old red blood cells) and help fight infections
-upper left of the abdomen, located behind the stomach and immediately below the diaphragm
-about the size of a thick paper back book and weighs just over half a pound
-is made up of lymphoid tissue
-the blood vessels are connected to the spleen by splenic sinuses (modified capillaries)
-the following peritoneal ligaments support the spleen:
-the gastrolienal ligament connects the stomach to the spleen
-the lienorenal ligament connects the kidney to spleen
-the middle section of the phrenicocolic ligament (connects the left colic flexure to the thoracic diaphragm)
-up to 10% of the population has one or more accessory spleens that tend to form at the hilum of the original spleen
