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
Portal circulation
o Renal Portal: Most vertebrates, Blood from tail to kidneys before it returns to heart
o Hepatic Portal: Blood from GI tract to liver before it returns to heart
Explain the difference between single circulaiton and double circulation
o Single circulation has one pathway, while double circulation has two pathways
o Single: Gills systemic capillaries heart
o Double: lungs heart
o Double: systemic capillaries heart lungs heart systemic capillaries
·What are blood islands and what do they make?
Seen in chick embryos
Local clusters of mesoderm are organized into blood islands after 18 hrs of incubation
intial makers of circulatory system, including introduction of RBCs and blood vessels
What happens to the paired endocardial tubes during development?
This pair of endocardial tubes fuses medially into the single endocardial tube (future lining of the heart
Describe embryonic heart formation
▪ Angiogenic cells emerge from the epimyocardium, a thickened splanchnic mesoderm
▪ Ventral (left) and corresponding cross-sectional (right) views of heart formation are illustrated
▪ Angiogenic cells differentiate into a pair of primordial endocardial tubes
▪ This pair of endocardial tubes fuses medially into the single endocardial tube (future lining of the heart)
▪ The thickened epimyocardium forms the thin peritoneum on the surface of the heart
▪ The extensive myocardium forms the muscular wall of the heart
