Human Physiology Test 4

the portion of the blood occupied by RBCs

what is hematocrit in a clinical setting?

elevated RBCs

what is polycythemia?

90%

what percent of plasma is water?

6-8%

what percent of plasma is proteins?

Na⁺ and Cl^-

what chemicals have a high concentration in electrolytes?

H⁺, HCO₃^-, K⁺, and Ca²⁺

what chemicals have a low concentration in electrolytes?

higher

plasma has a ________ protein concentration compared to interstitial fluid

liver

where are the proteins comprising plasma (albumin, globulin, fibrinogen, transferrin) synthesized?

major contributors to plasma colloid osmotic pressure; carries for various substances

what is the function of the protein albumin?

0mm Hg

what is the colloidal osmotic pressure in the interstitial fluid?

25mm Hg

what is the colloidal osmotic pressure of plasma?

“recaptures” the 3 liters of fluid that moves from the capillaries into the surrounding tissue on a daily basis and returns it to the circulatory system

what is the function of the lymphatic system?

the viscosity of the blood would increase which would increase resistance and negatively impact flow rate

what would happen without the lymphatic system?

edema

what does reduction in lymphatic system activity lead to?

hydrophobic molecules

what is albumin a carrier for?

hydrophobic molecules in the blood; role in clot formation

what are globulins a carrier for?

required for blood clot formation; cleavage required for activation

what is the function of fibrinogen?

iron in the blood

what is transferrin a carrier for?

plasma lacking fibrinogen and other clotting proteins

what is serum?

erythrocytes

what are the most abundant cells in the blood?

no organelles or nucleus

what is a key characteristic of erythrocytes?

transport O₂ and CO₂ / exchange with cells and lung

what is the major function of erythrocytes?

biconcave disk

what is the shape of erythrocytes?

it has a large surface area that favors diffusion

what is the benefit of erythrocytes having a biconcave shape?

passage through capillaries

what does the flexible cell membrane of erythrocytes allow for?

a molecule of the globin protein and 4 heme groups

what is hemoglobin?

4

how protein subunits does globin have?

2 ⍺ and 2 𝛾 subunits

what are the subunits fetal hemoglobin?

2⍺ and 2 β subunits

what are the subunits of adult hemoglobin?

an iron-containing group

what is heme?

4

how many hemes are in each globin complex?

98.5% of transported oxygen is bound to the iron in hemoglobin; the remaining is dissolved in plasma

what is the oxygen transport through hemoglobin?

exposure to elevated blood glucose levels

what modifies hemoglobin?

a single amino acid change in hemoglobin

what gives rise to fragile RBCs in sickle cell anemia?

an enzyme that converts carbon dioxide and water to carbonic acid

what is carbonic anhydrase?

bicarbonate and a proton

what does carbonic acid dissociate to?

maintains acid-base balance in the blood

what is the function of carbonic anhydrase?

120 days

what is the life span of red blood cells?

red bone marrow

where are red blood cells synthesized?

erythropoiesis

what is the process of red blood cell synthesis called?

hematopoietic stem cells

what stem cells do erythrocytes develop from in the bone marrow?

erythropoietin

what is erythrocyte synthesis stimulated by?

kidneys under conditions of low oxygen levels in blood

where is erythropoietin secreted from?

immature red blood cells; nucleus ejected but contains ribosomes

what are reticulocytes?

• obtained from diet

• recycled for synthesis of new hemoglobin

how is iron produced for erythrocyte production?

• taken up by endothelial cells of the small intestine

• transported in blood bound to transferrin and delivered to the bone marrow

how is iron obtained from the diet?

• spleen filters and removes old erythrocytes

• bilirubin is released into the bloodstream and travels to liver where it is broken down further. secreted in bile and travels to the intestinal tract or released into the bloodstream and excreted in urine

how is iron recycled for synthesis of new hemoglobin?

• spleen macrophages filter blood and phagocytose old/fragile RBCs

• the hemoglobin is broken down, the amino acids recycled, the iron removed, and the heme→ bilirubin

how does the spleen filter and remove old erythrocytes?

decrease in oxygen availability; often due to reduced RBCs or reduced RBC size

what is anemia?

deficiency in iron and folic acid

what is dietary anemia?

normal RBC number but reduced Hb; smaller RBC size

how is a deficiency in iron characterized?

reduced RBC number; larger and more fragile RBC

how is a deficiency in folic acid characterized?

a deficiency in vitamin B12 uptake due to loss of a protein required for uptake; reduced RBC number; larger and more fragile RBC

what is pernicious anemia?

lysis of RBCs due to infection or defects in RBC structure

what is hemolytic anemia?

defect in bone marrow; reduced RBC and WBC

what is aplastic anemia?

defect in the production of erythropoietin; reduced RBCs

what is renal anemia?

due to rapid loss of blood; reduced RBC for a short period of time

what is hemorrhagic anemia?

• neutrophils

• eosinophils

• basophils

• monocytes

• lymphocytes

what are the major groups of leukocytes?

leukocytes

what are the only nucleated cells in the bloodstream?

has roles in defense against foreign material/cells; perform phagocytosis of dead or damaged cells

what is the function of leukocytes?

thymus gland

where do T-cells migrate to develop into full maturity?

cell fragments that lack a nucleus but has organelles and granules; smaller than RBCs

what are platelets?

blood clotting

what important role in blood do platelets have?

megakaryocytes

what are platelets derived from?

edges of the cell extend out of the bone marrow and into a blood vessel; pieces of the cell fragmeent

how are platelets formed?

blood vessel damage → exposure of subendothelium → von Willebrand factor binds to collagen fibers → platelets bind to vWf → platelet adhesion, sticky, secretions

what is the flow of platelet initiation of plug formation?

these cells secrete prostacyclin and nitric oxide which prevents platelet aggregation

why do clots not form on undamaged endothelium?

clotting factors

what is produced in the liver?

inactive

what form of clotting factors are secreted into the blood?

cleavage

how are coagulation factors activated?

by interacting with proteins on the surface of activated platelets

how is thrombin cleaved?

fibrin

what does activated thrombin convert fibrinogen to?

a gel that traps RBCs to plug the damaged vessel and prevent blood loss

what does fibrin form?

• clotting factors produced by the liver

• activation of coagulation factors by cleavage

what is the formation of blood clots?

clotting disorders

what causes excessive bleeding?

a genetic disorder caused by deficiency of a specific coagulation factor

what is Hemophilia?

reduced levels of vWf which leads to decreased platelet plug formation

what is von Willebrand’s disease?

• hemophilia

• von Willebrand’s disease

• vitamin K deficiencies

what are some clotting disorders?

• warfarin

• aspirin

what are some inhibitors of clot formation?

inhibits an enzyme required for the recycling of vitamin K

what is the function of warfarin?

at low doses it inhibits an enzyme involved in platelet aggregation and plug formation

what is the function of aspirin?

the pressure gradient across the vessel and inversely related to resistance of the vessel

what is the rate of blood movement through the cardiovascular system related to?

85 mmHg

what is the median arterial pressure?

aorta

where is the median arterial pressure measured?

2-8 mmHg

what is the central venous pressure?

veins that lead to the right atrium

where is the central venous pressure measured?

• vessel radius

• vessel length

• blood viscosity

what factors influence resistance of blood vessels to blood flow?

a decrease in blood vessel radius, which increases resistance

what is vasoconstriction?

increase in blood vessel radius, which decreases resistance

what is vasodilation?

have a greater resistance but is not a major factor for adults

what effect do longer blood vessels have on blood pressure?

increases resistance but is not a major determinant of resistance over the short term

how does an increase in blood viscosity affect blood pressure?

the total cross-sectional area of the vessels

what is the primary determinant of velocity?

arteries and arterioles

what carries blood away from the heart?

arteries

which is bigger, arteries or arterioles?

veins and venules

what carries blood to the heart?

veins

which is bigger, veins or venules?

the smallest blood vessels

what are capillaries?

arterioles, capillaries, and venules

what is the microcirculation composed of?

epithelium cells

what lines all vessel lumens?

aorta

what is the largest artery?