The Circulatory System: Blood Outline Part 1

Circulatory Functions (3)

Transportation: oxygen, carbon dioxide, nutrients, waste, hormones and cells

Protection: immune cells, initiates clotting

Regulation: fluid balance, ECF pH stabilization, and temp control

Adults have how much blood?

4-6 liters of blood

Blood is a liquid connective tissue in cells + matrix what are these?

Matrix of blood: Plasma— clear, light yellow fluid

Cells: RBC, WBC, and platelets

7 kinds of formed elements in blood

1) erythrocytes (RBCs)

2) Platelets

Leukocytes (WBCs)

Granulocytes

3) Neutrophils

4) Eosinophils

5) Basophils

Agranulocytes

6) Lymphocytes

7) Monocytes

Hematocrit

% of volume of RBCs

anemia vs polycynemia

too few RBCs vs too many RBCs

Albumins (category of plasma protein) (abundance and what it does)

smallest and most abundant

• contribute to viscosity & osmolarity; influence BP & flow

Globulins (alpha, beta, antibodies) (category of plasma protein)(abundance and what it does)

2nd most abundant plasma protein

• transporters

• provide immune system function

Fibrinogen (category of plasma protein) (abundance and what it does)

least abundant plasma protein

• precursor of fibrin— help form blood clots

Blood plasma nitrogenous compounds

• free amino acids

• nitrogenous wastes (urea)

  • toxic end products of catabolism

  • removed by kidneys

Viscosity

resistance of fluid to flow, b/c of cohesion

thickness

honey is more viscous than water

Osmolarity of blood

total molarity of dissolved particles that cannot pass through BV wall

osmolarity of blood (too high vs too low)

blood absorbs too much water, BP increases

too much water stays in tissues (edema), BP drops

optimum osmolarity achieved by regulation of sodium, proteins, and RBCs

hypoproteinemia

deficiency of plasma proteins

• starvation or lack of dietary protein

• liver or kidney disease

kwashiorkor

in children with severe protein deficiency

• fed on cereals once weaned—swollen abdomen

Hemopoiesis

production of blood, especially formed elements

Hemopoietic tissues produce

blood cells

• yolk sac produces stem cells for first blood cells

• liver stops producing blood cells at birth

• spleen continues lymphocyte production

Hematopoietic stem cells (HSCs, make RBCs and WBCs) and then…

colony-forming units (CFUs)— specialized stem cells; produce one class of formed element

blast=immature cell

cyte=mature cell

Myeloid vs lymphoid hemopoiesis

blood formation in bone marrow vs lymphatic organs

erythrocyte functions

• carry oxygen from lungs to tissues

• pick up carbon dioxide from tissues and bring to lungs

erythrocyte form

disc-shaped cell with thick rim

• lose nearly all organelles during development

• lack mitochondria and nucleus/DNA

• cytoskeletal proteins (spectrin and actin) give membrane durability and resistance—helps it squeeze through small capillaries

erythrocyte gas transport

33% of cytoplasm is Hemoglobin (Hb)

oxygen delivery to tissues and carbon dioxide transport to lungs

carbonic anhydrase (CAH) in cytoplasm of erythrocyte

produces carbonic acid from CO2 and water

important for gas transport and pH balance

Hemoglobin anatomy

4 protein chains—globins

4 heme groups

Heme groups

nonprotein moiety that binds oxygen to ferrous ion at center (this is why RBC can carry so much oxygen)

Globins

4 protein chains

2 alpha and 2 beta chains

fetal hemoglobin… likes it better than in an adult hemoglobin!

oxygen

how many erythrocytes in blood?

5 million per microliter

erythrocyte production process

First committed cell: erythrocyte CFU (erythropoietin (EPO) acts on CFUs to make RBCs)

Erythroblasts multiply and synthesize hemoglobin

Nucleus discarded to form reticulocyte (1% of RBCs)

Iron is a key nutritional requirement for

Hemoglobin!

• lost daily through urine, feces, and bleeding

• men 0.9 mg/day, women 1.7 mg/day

Vitamin B12 (meat and fish) and folic acid (leafy greens) good for

mitosis in erythropoiesis

Vitamin C (citrus fruits) and copper (mushrooms and oysters) good for

enzymes synthesizing hemoglobin

Erythrocyte negative feedback for when RBC count drops

causes kidney hypoxemia (low levels of oxygen)

kidney production of EPO stimulates bone marrow

RBC count increases

Stimuli for increasing erythropoiesis

• low levels O2 (hypoxemia)

• high altitude

• increase in exercise

• emphysema (lung disorder/ lack surface area in lungs)

RBCs lyse in narrow channels in…

spleen

Macrophages in spleen: digest and separate heme from globin

Globins hydrolyzed into amino acids

Iron removed from heme

• heme converted to biliverdin

• biliverdin converted to bilirubin, released into blood

• liver takes bilirubin and secretes into bile

• bile concentrated in gall bladder: released into small intestines; bacteria create urobilinogen

Polycythemia def and dangers

excess RBCs

increased blood volume, BP, viscosity—risk of stroke, heart failure

Primary polycythemia (polycythemia vera)

cancer of erythropoietic cell line

Secondary polycythemia

dehydration, emphysema, high altitude, or physical conditioning

3 causes of Anemia

1) Inadequate erythropoiesis or hemoglobin synthesis

2) Hemorrhagic anemias from bleeding

3) Hemolytic anemias from RBC destruction

pernicious anemia

inadequate vitamin B12

hypoplastic anemia

slowing of erythropoiesis

aplastic anemia

cessation of erythropoiesis

3 consequences of anemia

tissue hypoxia and necrosis (tissue death from disease)

• short of breath; necrosis of vital organs

blood osmolarity reduced, producing tissue edema

blood viscosity low

• heart races, BP drops

Sickle-Cell disease

Hereditary hemoglobin defects

Caused by recessive allele, modifies structure of hemoglobin

Hemoglobin does not bind oxygen well

clump together and can block blood vessels—intense pain

risks: kidney/heart failure, stroke, or paralysis