Body Systems: Circulatory/Immune Systems (Structures And Functions Of The Circulatory System) Flashcards
Functions of the circulatory system:
- Transports gasses and wastes.
- Regulates internal temp, transports hormones.
- Protects against blood loss from injury (platelets), provides immune response.
Major components of the circulatory system:
- Heart
•Pumps blood through body, generates blood flow. - Blood vessels
•”roadways” for blood, arteries, veins, capillaries. - Blood
•Carries nutrients, O2, CO2, wastes and other materials throughout body.
The heart:
-Located slightly left of middle of chest.
-O2 rich blood is kept separate from O2 poor blood.
-Blood flows in one direction.
-Made up of cardiac muscle.
-Contractions are rhythmical and involuntary.
Structures of the heart:
-Atria (Singular = atrium): two chambers at the top.
-Ventricles: two chambers at the bottom.
-Septum: thick muscular wall.
-Pericardium: fluid filled membrane surrounding the heart.
-Atrioventricular (AV): separate atria from ventricles.
-Semilunar (SL) valves: separate ventricles from arteries.
Where is the atria and ventricles located?
-Atria (plural) are found at the top of the heart, there is a right atrium and a left atrium.
-Ventricles are on the bottom of the heart also split into left and right.
Pericardium:
-Tough inelastic sheath covering heart.
-Anchors heart.
-Acts as a constraint to enable ventricular interaction.
-Pericardial fluid.
-Lubrication.
One-way valves:
-The heart has one-way valves between atria and ventricles and in the aorta and pulmonary arteries to ensure blood flows in the correct direction.
-Directs blood towards the heart.
-Fighting gravity.
-They do not allow blood to flow back in the other direction.
-Tricuspid valve (Atrioventricular valve).
-Bicuspid valve (Mitral valve, atrioventricular valve).
-Semilunar valves.
-Pulmonary and aortic.
Legend (Blue):
-Blue = deoxygenated blood.
-Blood returning from tissues.
-Low O2 content (because it’s just delivered all of its O2 to the tissues).
-Heading towards tissues to deliver O2.
Legend (Red):
-Red = oxygenated blood.
-Blood leaving lungs filled with O2.
-Heading towards tissues to deliver O2.
Pathway of blood:
- O2 poor blood coming back from body is pumped through the vena cava (right side of the heart) into the right atrium.
- Blood flows from right atrium to right ventricle and then out the left and right pulmonary arteries to the lungs for gas exchange.
- O2 rich blood from the lungs returns to the heart through left and right pulmonary veins.
- O2 rich blood enters the left atrium then the left ventricle.
- O2 rich blood leaves the heart through the aorta to be delivered throughout the body.
Structures of the blood vessels: arteries:
-Carry blood away from the heart.
-Highly elastic walls.
-Your pulse is the contraction of the artery as blood moves through it.
-Deoxygenated blood leaves the right side of the heart to the lungs via pulmonary arteries.
-Oxygenated blood leaves the left side of the heart via aorta.
Structures of the blood vessels: capillaries
-Smallest blood vessels.
-Capillary walls = single layer of cells.
-Diameter of capillaries is 8 um, just wide enough for a red blood cell.
-Site of gas, nutrient and waste exchange between blood and cells.
Structures of the blood vessels: veins
-Carries blood towards the heart.
-Thinner walls than arteries.
-Not as elastic, cannot contract to move blood back to the heart.
-Rely on contraction from surrounding skeletal muscle.
-One-way valves to prevent back flow against gravity.
-Deoxygenated blood returns to the right side of the heart via vena cava.
-Oxygenated blood returns to the left side of the heart via pulmonary veins.
Varicose veins:
Varicose veins occur when the leaflets of valves fail to close properly, causing blood to flow backwards and pool in the veins.
Arteries*:
-3 distinct layers:
1. Elastic connective tissue.
•Endothelium.
2. Smooth muscle.
•Middle layer.
•Larger in arteries.
3. Elastic connective tissue.
•Outer and inner layers.
