Ch. 17 The Cells Flashcards
Functions and Characteristics of Blood
Functions:
1. transport O2, CO2, nutrients, hormones, heat and waste products
2. regulate homeostasis of all body fluids, pH, body temp., and water contents
3. protect against excess loss by clotting and uses WBCs to protect against infections
Properties of Blood
- viscous, dense/thick
- makes up about 8% of body weight
- coloration depends on oxygenation
high O2= bright red, scarlet
low O2= dark and dull - Normal pH- 7.35-7.45
Components of Blood
Plasma- liquid/fluid component (55%) contains dissolved substances and suspends formed elements
Formed Elements- solid components of blood (45%)
red blood cells/erythrocytes (45%)
white blood cells/leukocytes (<1%)
platelets/thrombocytes (<1%)
Characteristics and Composition of Plasma (inorganic and organic substances)
A. 1. 55% of total volume
2. suspends formed components
3. dissolves organic and inorganic substances
B. inorganic substances:
a. electrolytes: Na+, K+, Ca+2
b. respiratory gases: O2 and CO2
c. Nitrogenous wastes: urea and uric acid
C. Organic substances:
a. Hormones: insulin, estrogen/testosterone
b. Nutrients: absorbed carbs, proteins, lipids, etc.
c. Plasma proteins: not for nutriental consumption
1. Albumin: exert osmotic pressure to maintain fluid homeostasis
2. Globulins: various functions but immunoglobulins=antibodies
3. Fibrinogen: protein important for clotting
Formed Elements: general characteristics
- 45% of total blood volume
- common stem cell. original from bone marrow
- RBCs and platelets are not true cells
- mostly amitotic/no mitosis, short life span
- RBCs outnumber WBCs and platelets
- homeopoiesis: blood cell formation
Erythrocytes: characteristics
- Biconcave, anucleate discs full of hemoglobin (protein)
- Shape maximizes gas diffusion
- flexible
- Contributes to blood viscosity/thickness
- Hemoglobin (hgb)
a. hem- red pigment, contains iron that bind O2
b. globin- proteins composed of amino acids, binds CO2
Erythropoiesis
Def: formation of RBCs
2. Stem cells: hemocytoblast
3. Reticulocyte: underwent….
a. ribosome synthesis: create organelles that synthesize proteins
b. Hgb accumulation: new ribosomes produce hgb
c. Nucleic extrusion: eject nuclei
d. erythrocyte: typical biconcave, anucleate disc
Regulating Erythropoiesis: hormonal neg. feedback
- stimulus: hypoxia/ low O2 levels
possible cause: altitude change, hemorrhage, anemia - Response: kidneys secrete EPO (erythropoietin, hormone that stimulates RBC production)
- In bone marrow, hemocytoblasts (stem cells) respond to EPO
- Mature RBCs enter the bloodstream
- Results: O2 levels normalize
Life Cycle of the RBCs
Brand new RBCs circulate within the bloodstream for about 120 days
1. Damaged and dead RBCs will be filtered in the liver.
phagocytic cell type: macrophages
2. Hemoglobin is broken into hem and globin protein
3. Globin portion of hgb- amino acids are returned to bloodstream
4. Iron component of heme is transported by: transferrin
5. Iron is stored within: Liver
and stored within: proteins ferritin and hemosiderin
6. iron is released from storage and transported by: transferrin
7. In the bone marrow, we need: iron, amino acids(through proteins in diet) vitamin B12 and folic acid (iron absorption)
EPO from Kidneys
8. Erythropoiesis occurs
9. Pigment of heme discarded
10. bilirubin within bloodstream is sent to liver
11. Bilirubin is converted into urobilin and stercolbilin and sent to kidneys (yellow urine) and intestines (brown stole) to be eliminated.
Leukocytes: characteristics
- True nucleated cells
- normally, <1% of total blood volume
- 5 types of WBCs
- main functions: to protect against disease
5 types of WBCs: Granulocytes and Agranulocytes
Granulocytes: (-PHILS) developed in the bone marrow, have cytoplasmic granules, short lifespans
1. Neutrophils- most abundent light purple stain, multilobed, segmented nuclei
function- phagocytic
2. Eosinophils- red stain, pink, bilobed
function- attacks parasites, involved in inflammation, allergy reactions
3. Basophils- least abundant, deep blue/purple. thick granules, multi-lobed
Function- secrete heparin (natural anticoagulant) secretes histamines
(inflammatory chemical)
Agranulocytes- both develp in the bone marrow but lymphocytes mature in the lymphatic system, lack cytoplasmic granules, longer lifespans
4. Monocytes- large dark stain, U shaped/kidney shaped nuclei
Function- matures into phagocytic macrophages
5. Lymphocytes- smallest WBC, dark-stained round nuclei with thin rim/halo of cytoplasm
Function- secrete antibodies
Never Let Monkeys Eat Bananas
Mobilizing Leukocytes: WBCs response to inflammation
- Injured tissues will secrete inflammatory chemicals
- Inflammatory chems will trigger leukocytosis, WBCs are recruited out of the bone marrow
margination: WBCs cling to blood vessel walls - Diapedesis: WBCs exit bloodstream (squeeze)
- Chemotaxis: WBCs follow chemical trails to find source of inflammatory chems
- Once at the site of injury, phagocytic cells do their job then die
Thrombocytic/-cytes: characteristics
(thrombo-clotting)
1. cell fragments, only live for 10 days
2. formation triggered by TPO (thrombopoietin)
3. involved in blood clotting
Thrombopoiesis
- stem cells: hemocytoblast
- hormone trigger: TPO
- platelet precursor: megakaryocyte (breaks down to create platelet)
- platelets: cell fragments, used as plugs
Hemostasis
- def: stoppage of bleeding
- vasospasm/vascular spasm/vasoconstriction: vessels contract to try to pinch off blood flow. effective in small vessels less so in large ones
- platelet plug formation: platelets adhere to any rough surface and exposed collagen
+ feedback loop initiates, creating a layer upon layer of platelets to form a plug
requires Von Willebrand factor/clotting factor to keep plug stable - Coagulation: most effective means of hemostasis: requires clotting factors to allow enzyme thrombin to be activated
Activated thrombin converts dissolved fibinogen to insoluble thread-like fibrin/mesh like threads
