Circulatory System Flashcards
Blood Pathways
- Systemic Pathway: to/from body cells
- Pulmonary Pathway: to/from lungs
- Cardiac Pathway: to/from heart muscles
Functions
Transport, defense, repair, body temp regulation, maintaining water levels
Red Blood Cells (Erythrocytes)
Specialized with hemoglobin (has iron) that carries oxygen (sometimes carbon dioxide); biconcave disk to increase surface area for gas exchange
White Blood Cells (leukocytes)
Defends against bacteria and viruses, increases when body is fighting infection
Platelets (thrombocytes)
Reacts with clotting factors to form temporary clots (thrombus) to prevent blood leakage
Plasma
Clear, yellowish fluid (55% of total blood volume, made up of 92% water) - carries blood components, salt, enzymes, water, clotting factors, and maintains fluid balance
Counting Blood Cells
Low RBCs - leads to anemia (from bleeding or iron-defiency) –> feels tired
High WBCs - body is fighting infections –> symptom is leukemia (cancer of bone marrow and blood)
Arteries
Carries oxy blood from heart to body cells (exception - pulmonary artery: carries deoxy blood from heart to lungs) –> disorder: aneurysm (rupture)
Artery Structure
Large, muscular, thick-walled with small inner diameter (three layers of tissue) and very elastic - contraction of heart = arteries slightly expand = your pulse
Veins
Carries deoxy to heart from body cells (exception - pulmonary vein: carries oxy blood from lungs to heart) - skeletal muscle contractions help move blood (against gravity)
Vein Structure
Large, thin-walled (middle layer isn’t as thick), less elastic, large inner diameter (lower pressure), with valves
Capillaries
Microscopic, one cell thick (inner diameter < 7 μm) that connect arteries and veins - low pressure, blood cells single file for gas exchange/nutrient-waste exchange
Vasoconstriction
Nerve impulses cause smooth muscle in arterioles to constrict - narrows vessel diameter (occurs when cold - keeping heat)
Vasodilation
Nerve impulses cause smooth muscle in arterioles to relax - increase vessel diameter (occurs when warm - loses heat to environment)
Systolic Pressure
Pressure in blood vessels when heart beats (contracts and empties blood)
Diastolic Pressure
Pressure in blood vessels when heart rests between beats (relaxes and fill with blood)
Normal Blood Pressure
120 mm Hg / 80 mm Hg - measured in milliters of mercury
Factors in Blood Pressure
Related to distance from heart (higher in arteries than veins - inner diameter)
1. Demand on heart for blood (e.g. higher during exercise)
2. Vasoconstriction –> more blood left in artery –> increased blood pressure
Hypertension
High blood pressure
Heart Node
Specialized type of tissue that acts as muscle and nervous tissue
Heart Beat
Set by natural pacemaker - sinoatrial (SA) node located where vena cava enters right atrium. When nodal tissue contracts, sends nerve impulses through heart walls, triggers atrioventricular node to do same (helps power cardiac cycle)
Heart Sounds
Sound of heart contracting and valves opening/closing produces “lubb-dubb”; abnormal heart sound (“whoosh”) = heart murmur
Electrocardiogram Waves
P wave: atrial contraction
QRS wave: ventricular contraction
T wave: signals ventricles have recovered
Flat line: no heart contraction (no activity)
The Heart
4-chambered double pump
Right Side of the Heart
Receives deoxy blood from body via superior and inferior vena cava, pumps blood to lungs via pulmonary artery
(pumps blood to pulmonary circuit)
Left Side of the Heart
Receives oxy blood from lungs via pulmonary vein, pumps blood to body via aorta
(pumps blood to the systemic circuit)
