chapter 12 Flashcards
Two Types of Circulatory Systems
- Open System:
Blood flows freely within the body cavity.
Makes direct contact with organs and tissues.
Example: Insects, crustaceans. - Closed System:
Blood is physically contained within vessels.
Blood follows a continuous fixed path.
Example: Earthworms, birds, humans.
Structure of the Heart
- The heart consists of two double pumps separated by the septum.
- The right pump receives deoxygenated blood to the lungs (pulmonary circuit).
- The left pump receives oxygenated blood to the cells of the body (systemic circuit).
-Blood flow through the heart is called the cardiac circuit.
Valves in the Heart
Atrioventricular Valves:
Tricuspid valve (right atrium to right ventricle).
Bicuspid valve (left atrium to left ventricle).
Semilunar Valves:
Aortic and pulmonary valves.
Valves control the flow of blood through the heart.
Heart murmur may occur if valves don’t close properly.
The Four Chambers of the Heart
The heart has four chambers: two atria and two ventricles.
Blood Vessels
Arteries:
Carry blood away from the heart at high pressure.
Made up of three strong layers.
Veins:
Carry blood towards the heart at lower pressure.
Thinner than arteries.
Have one-way valves to keep blood moving forward.
Capillaries:
Narrowest blood vessels.
Allow for slow blood flow and low pressure.
Facilitate gas exchange through diffusion.
Recap: Overall Flow
Arteries → Arterioles → Capillaries → Venules → Veins.
The Overall Path of Blood (in a closed system)
Arteries → Arterioles → Capillaries → Venules → Veins → Heart.
Components of Blood
Blood consists of plasma (55%) and cells (45%: RBCs, WBCs, and platelets).
Red Blood Cells (Erythrocytes)
-Made in bone marrow, contain hemoglobin.
-Biconcave shape for maximum O2 transport.
-Hemoglobin gives blood its red color.
Blood Doping
-Athletes may undergo blood doping to increase RBC count for enhanced performance.
Anemia
-Decreased hemoglobin in the blood.
-Can be caused by genetic disorders or lack of dietary iron.
White Blood Cells (Leukocytes)
-Made in bone marrow.
-Defend against foreign invaders.
-Some use phagocytosis to engulf pathogens
Platelets (Thrombocytes)
-Cell fragments that initiate blood clotting.
-Form a plug to prevent further bleeding.
Functions of Blood: Temperature Regulation
-Circulatory system regulates temperature by changing blood flow near the skin.
- Vasodilation releases heat, vasoconstriction conserves heat.
Cardiovascular Disease Risk Factors:
Smoking
Obesity or poor diet
Insufficient exercise
Genetics
Arteriosclerosis:
Thickening and loss of elasticity in
artery walls
Atherosclerosis: Plaque buildup leading to narrowed arteries, increased blood pressure
Potential outcomes: Angina, blood clots, shortness of breath, heart attack, heart failure
Prevention: Healthy lifestyle
Treatment: Aspirin, medications encouraging blood flow and thinning blood
Angioplasty:
Tube inserted into a clogged artery
Tiny balloon inflates to force the artery open
Stent (wire-mesh tube) may be inserted to hold vessel open
Coronary Bypass:
Rerouting blood flow around blocked arteries
Using artery or vein to create a new pathway for blood
Double, triple, or quadruple bypass depending on blockages
Stroke:
Ischemic stroke: Blood vessel clot blocks blood flow to the brain
Hemorrhagic stroke: Brain blood vessel bursts, causing bleeding
Longer time without oxygen increases the risk of permanent damage
Treatment: Clot-busters or surgery, must begin immediately for effectiveness
Aneurysm:
Artery bulge caused by weakened arterial wall
Blood pressure can cause aneurysm to grow larger, leading to bursting and internal bleeding
Most aneurysms occur in the aorta
Treatment: Surgery to replace portion with patch/graft made of synthetic material
Heart Valve Diseases:
Regurgitation: Valves do not close completely, causing blood to flow backward
Left side results in deficiency of oxygenated blood
Causes: Aging, previous heart attack, or infection
Treatment: Repair or replacement with human, animal, metal, plastic, or synthetic alternatives
Arrhythmia:
Problem with speed or rhythm of heart beat
Can lead to insufficient blood flow to the brain or other organs
Treatment: Medications or surgery to implant an artificial pacemaker
Congenital Heart Defects:
Present since birth
Problems in walls dividing heart chambers, valves, and structure of heart blood vessels
Surgeons can often successfully repair or reduce damage
Disorders of the Blood: Anemia:
Blood contains fewer than normal healthy red blood cells
Not enough iron/hemoglobin
Symptoms: Dizziness, fatigue, shortness of breath, headache, and cold extremities
Treatments: Dietary iron supplements
