Circulatory System Flashcards
function of blood
transport:
- move respiratory gases (O2 to tissues, CO2 waste to lungs), nutrients, wastes, hormones, stem cells
protection:
- contains WBCs that destroy microorganisms and cancer cells, and produce antibodies that help fight infections
- platelets clot the blood if vessels have been injured to minimize blood loss.
regulation:
- capillaries help to stabilize fluid distribution in the body
- the blood contributes to optimal pH by buffering acids and bases
- shifts in blood flow regulate body temperature.
plasma
a complex clear, extracellular fluid of water, proteins, nutrients, electrolytes, hormones, and gases
- serum is what remains when solids are removed
- mostly water (92% by weight)
- proteins (most abundant plasma solute): albumin, globulins, and fibrinogen
- nutrients: glucose, amino acids, lactic acid, lipids, and others
- electrolytes: salts of Na, K, Mg, Ca, Cl, and others
- nitrogenous wastes: urea and others
- hormones
- gases: oxygen, carbon dioxide, and nitrogen
proteins in plasma
- albumin: most abundant and acts to transport solutes, buffer pH, and contributes to viscosity and osmolarity
- globulins play roles in transport, clotting, and immunity
- fibrinogen: (precursor of fibrin, a clotting protein) the liver produces all of the major blood proteins except gamma globulins, antibodies which come from plasma cells (descendants of B lymphocytes).
contents of blood
- plasma (55%): clear extracellular fluid (matrix)
- formed elements (45%): liquid connective tissue; cells and cell fragments ; they include erythrocytes (RBCs), platelets (fragments of bone barrow cells), and five kinds of leukocytes (WBCs).
erythrocytes
Function:
- hemoglobin (component of the RBC cytoplasm): transports nearly all of the O2 and some of the CO2 in the blood
Shape:
- discoid cells with a sunken center
- no nucleus, mitochondria, or organelles, but they do have a cytoskeleton of spectrin and actin that reinforces the plasma membrane
7 major formed elements
- erythrocytes: RBCs (transport gases)
- leukocytes (monocytes, lymphocytes, neutrohils, basophils, eosinophils): WBCs (immune responses)
- thrombocytes: platelets (initiates clotting)
formed elements: erythrocytes
- discoid cells with sunken center & no nucleus
- function mainly to transport O2 and CO2
- most abundant formed element
formed elements: monocytes
- 3-8%; nucleus ovoid/kidney shaped
- sparse nonspecific granules
- function to phagocytize
- differentiate into macrophages
- present antigens
WBC
formed elements: lymphocytes
- 25-33%; nucleus ovoid/round
- may be small or large
- function to destroy cancer cells, foreign, viral cells
- initiate an immune response
- secrete antibodies
WBC
formed elements: neutrophils
- 60-70% nucleus usually with 3-5 lobes
- red/violet granules
- function to phagocytize bacteria
- secrete antimicrobials
WBC
formed elements: eosinophils
- 2-4%; nucleus with 2 large lobes, connected by thin strand
- orange/pink granules
- function to phagocytize antigen-antibody complexes, allergens, and inflammatory chemicals, secrete enzymes to weaken & destroy parasites
WBC
formed elements: basophils
- <0.5%; nucleus large & irregular
- coarse, dark granules
- function to secrete histamine and heparin
WBC
formed elements: platelets
- fragments of bone marrow cells
- second most abundant formed element
- no nucleus, but do have other organelles
- function to form clots, dissolve clots, vasoconstrict, attract WBCs, destroy bacteria
hemostasis
“cessation of bleeding”
steps:
1. when a blood vessel is injured, platelets release serotonin, which triggers vasoconstrictor to minimize blood loss
2. the platelets then adhere to the vessel wall and each other, forming a platelet plug
3. the platelets release clotting factors that convert the protein fibrinogen to fibrin. together, the fibrin, platelets, and blood cells form a clot that seals the breach
4. once the leak is sealed, platelets secrete a growth factor that stimulates fibroblasts and smooth muscle to replace the damaged tissue
5. finally, platelets secrete factor XII that leads to the formation of plasmin, a fibrin-digesting enzyme that dissolves the old clot
thrombocytosis
condition in which there are too many platelets, resulting in abnormal clotting; abnormal clotting of an unbroken blood vessel (thrombosis)
B cells
- type of WBC created in the bone marrow for immune protection
- differentiate into plasma cells- secrete antibodies to fight infection
- some may become memory cells (like T cells) to confer long-lasting immunity
histamine
a vasodilator secreted by basophils which increases blood flow to an injured tissue, and makes blood vessels more permeable so that blood components can get in more quickly
white blood cells
types: monocytes, lymphocytes, neutrohils, basophils, eosinophils
function: immune responses
composition of the heart wall
- epicardium: serous memberane; thin outer layer that consists of simple squamous epithelium on top of areolar tissue also includes thick layer of adipose tissue in some places
- myocardium: thick middle layer of the heart; composed of cardiac muscle (cardiomyocytes), coil around the heart in a spiral (vortex pattern) ; also contains connective tissue framework (fibrous skeleton)
- endocardium: thin inner wall lines the interior of the heart and is continuous with inner lining of blood vessels; simple squamous epithelium overlying thin areolar tissue, but no adipose tissue
a drop of blood returning from the big toe would enter the heart through what vessel?
inferior vena cava
coronary arteries
blood vessels that branch from the aorta and carry oxygen-rich blood to the heart muscle (LCA & RCA)
left coronary artery (LCA)
travels through the coronary sulcus under the left auricle and divides into two branches: anterior interventricular branch and circumflex branch
- anterior interventricular branch: runs along the anterior interventricular sulcus; it supplies both ventricles and the anterior interventricular septum
- the circumflex branch: continues around the left side in the coronary sulcus and supplies the left atrium and the posterior wall of the left ventricle.
right coronary artery (RCA)
supplies the right atrium sinoatrial node (pacemaker) then continues along the coronary sulcus under the right auricle; gives off two branches: the right marginal branch and the posterior intervertebral branch
coronary circulation
circulation of blood through the coronary blood vessels to deliver oxygen and nutrients to the heart muscle tissue; most variable aspect of cardiac anatomy
atrium vs. ventricle muscularity
atria: thin-walled, as they only pump blood into ventricles
ventricles: thick-walled, need to be able to pump blood into arteries
left vs right ventricle muscularity
right ventricle: moderately muscular wall, only pumps blood to lungs and back to left atrium
left ventricle: muscular wall is 2-4x as thick as right, pumps blood through entire body; greatest workload of all 4 chambers
which vessel carries oxygenated blood from the heart to the tissues of the body?
aorta- gives rise to all systemic arteries
“pacemaker” of the heart
sinoatrial (SA) node
- located in the right atrium
- consists of myocytes that initiate each heartbeat and determines heart rate
sympathetic stimulation to the heart
- function: increases force and rate of contraction and dilation of coronary arteries
- origin: lower cervical and upper thoracic regions
- path: fibers from sympathetic neurons run to the sympathetic chain gangllia and from there, postganglionic fibers travel to the heart in cardiac nerves
the great vessels
- pulmonary trunk
- aorta
- superior and inferior vena cava
- pulmonary veins
aorta (origin)
large arterial trunk that carries blood from left ventricle of the heart to be distributed by branch arteries through the body
brachiocephalic trunk
- responsible for carrying blood from your aorta to your right subclavian artery and right common carotid artery
- 2 main branches: right and left subclavian artery
deep veins of the forearm
- radial
- ulnar veins
major branches of the hepatic portal vein
- left portal vein
- right anterior portal vein
- right posterior portal vein
capillaries
microscopic vessels connecting small arteries to small veins
continuous capillary
- most common type of capillary
- have a wall where the endothelial cells fit very tightly together
- continuous tube like a water hose
fenestrated capillaries
- have endothelial cells riddled with patches of filtration pores
- allow for rapid passage of small molecules, protein hormones, but keep larger proteins particles in bloodstream
- rapid absorption or filtration (kidneys, endocrine glands)
sinusoids
- irregular blood-filled (shaped) spaces in the liver, bone marrow, spleen, and some other organs
- endothelial cells separated by wide gaps & no basal lamina, large fenestrations
- fxn: convey oxygen-rich hepatic arterial blood and nutrient-rich portal venous blood to the hepatocytes and eventually drain into the central vein, which drains into the hepatic vein- similar to capillaroes just irregular shape
think sine graph (iregular shape)
arteries
- resistance vessels
- thick walls to withstand the pressure of blood pumped by the hearts
- carry blood away from heart
veins
- capacitance vessels
- walls with a thinner muscle layer and larger lumen to accommodate increased volume of blood
- carry blood back toward heart from tissue
