Chapter 12 Circulatory System Flashcards
What are the functions of the circulatory system?
- Gases
- Nutrients
- Waste products
- Hormones
- Heat
- Various other materials
Components of blood
plasma, buffy coat(platelets and leukocytes), ertrocytes
Plasma
55% in blood
▪ Mostly water
▪ Proteins (albumin)
▪ Electrolytes
▪ Dissolved gases
Buffy Coat
1% in blood
· Leucocytes (WBCs)
· The immune system
· Platelets: clottin system
Erythrocytes
45% in blood
▪ Erythrocytes (RBCs)
▪ Carries oxygen (hemoglobin)
Venules/veins
▪ Carry blood back to the heart
▪ Less muscle in their walls but are very elastic
▪ Begin at the end of capillary beds
Arteries/arterioles
▪ Carry blood away from the heart
▪ Have muscular, elastic walls
▪ Terminate in capillary beds
Capillaries
▪ Have very thin walls (endothelium only)
▪ The site of exchange between the blood and body cells
Understand the route of blood flow
starts in the heart, where oxygen-poor blood is pumped from the right ventricle to the lungs via the pulmonary artery
In the lungs, blood gets oxygenated and returns to the left atrium through the pulmonary veins
Oxygen-rich blood is then pumped from the left ventricle into the aorta and distributed throughout the body via arteries
After delivering oxygen and nutrients to tissues, the now deoxygenated blood returns to the heart through veins, completing the cycle
Microcirculation
o Controls blood flow to the capillary bed
▪ Arteriole leads into capillary bed, and then venule back to heart
▪ Oxygenated heart into capillary bed, sphincter regulates blood flow in
▪ Oxygenated blood then leaves through venules, back to heart
▪ Level at which nutrient and gas exchange take place
Describes the hemodynamics of blood flow
o As blood flows from large arteries to capillaries and veins, the initial pressure imparted by the force of heart contraction falls
o Capillaries have an especially large cross-sectional area
Function of the valves in veins?
o One-way valves in veins
o Prevent retrograde movement of blood and ensure its return flow toward the heart
o Blood flowing upwards, valve closes if blood flows backwards
Subdivisions of circulatory system
systemic circulation, pulmonary circulation, portal circulation(renal and hepatic)
Systemic circulation
Circulation to body and back to heart; Includes gills in fishes
Pulmonary circulation
Heart to lungs to heart, Found in tetrapods ; Partial separation in amphibians, most reptiles; Complete separation in birds, mammals
