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Histology > Blood - Specialised Connective Tissue > Flashcards

Blood - Specialised Connective Tissue Flashcards

1
Q

blood is a specilised connective tissue, what does it consist of?

A

formed elements: erythrocytes, leukocytes and platelets

fluid component: plasma

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2
Q

how much blood is found in an average human adult?

A

approximately 5L

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3
Q

what does blood regulate?

A

body temperature

also assists in regulation of osmotic and acid-base balance

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4
Q

by what process is blood cellscontinuously replaced?

A

hemopoiesis

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5
Q

blood constituents: what does plasma consist of?

A

90% water
9% organic compounds
1% inorganic salts, dissolved gases and nutrients

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6
Q

blood constituents: what are the main proteins found in plasma?

A
  • albumin
  • y-globulins
  • a-globulins and b-globulins
  • clotting proteins (fibrinogen)
  • complement proteins (part of innate immune system)
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7
Q

blood constituents: what is albumin is plasma?

A

albumin is a small protein found in plasma. it preserves the osmotic pressure in the vascular system and helps transport some metabolites.

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8
Q

blood constituents: in blood, what is serum?

A

serum is a yellowish fluid that remains after blood has clotted. it is similar to plasma but lacks fibrinogen and clotting factors

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9
Q

blood constituents: erythrocytes is a formed element of blood, what are the general features of erythrocytes?

A
  1. erythrocytes are round, biconcave cells that stain light pink with Wright or Giemsa stains
  2. erythrocytes do not have a nucleus
  3. mature erythrocytes do not possess organelles but are filled with hemoglobin (Hb)
  4. the average life span of an erythrocyte is 120 days
  5. A, B and O blood groups are determined by carbohydrates located on the external surface of the erythrocyte’s plasmalemma
  6. several cytoskeletal proteins maintain the shape of RBCs (spectrin and actin)
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10
Q

blood constituents: what is the life span of an erythrocyte? how are they removed from circulation?

A

RBCs have a life span of 120 days

aged RBCs are fragile and express membrane surface oligosaccharides that are recognised by splenic, hepatic and bone marrow macrophages, whcih destroy those RBCs

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11
Q

blood constituents: on average, how big are erythrocytes?

A

6.7 to 7.7 um

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12
Q

blood constituents: what is the hematocrit?

what are the standard values?

A

the hematocrit is an estimate of the volume of packed erythrocytes per unit volume of blood.
the hematocrit is expressed as a percentage

  • in male adults: 40-50%
  • in female adults: 35-45%
  • in children under 10: 35%
  • in newborns: 45-60%
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13
Q

blood constituents: what is Hemoglobin? what are the most common Hb chain composition?

A

hemoglobin is a protein composed of four polypeptide chains each covalently linked to a heme group.

the four chains that normally occur in humans are: a, b, y, o. each chain differs in its amino acid sequence

Hb occurs in several normal forms that differ in chain composition:

  • predominant form of adult Hb is HbA (a2b2)
  • minor form of Hb is HbA2 (a2o2)
  • foetal form of Hb is HbF (a2y2)
  • sickle cell Hb is abnormal form HbS
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14
Q

blood constituents: What is the cause of sickle cell anemia?

A

sickle cell anemia is cuase by a point mutation in the b-chain of hemoglobin, forming HbS an abnormal form of hemoglobin.
- (substituion of the amino acid valine for glutamate)

erythrocytes containing HbS are sickle shaped and fragile.

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15
Q

how much CO2 is produced by cells of the body every minute?

A

200ml

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16
Q

how is CO2 transported from tissues into the capillaries?

what is the fate of the 200ml CO2 that is formed every minute?

A

CO2 partial pressure is greater in the tissue than in the capillaries, so CO2 is transported into capillaires via simple diffusion

  • 20ml of CO2 is transported into the plasma
  • 40ml binds to globin moiety of Hb (carbaminohemoglobin)
  • 140ml enters the RBC cystol
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17
Q

what happens to the CO2 when it is transported from the tissues into the RBC cytosol?

A

the enzymes, carbonic anhydrase forms H2CO3 by combining CO2 and H2O.

the H2CO3 dissociates and the HCO3- leaves the RBC to enter the plamsa, Cl- enters from the plasma to maintain electrical equilibrium (chloride shift)

18
Q

related to RBCs, what is the chloride shift?

A

the chloride shift occurs when bicarbonate ions leave the RBC cytosol and chloride ions enter to maintain the electrical equilibrium

the reverse of the chloride shoft occurs when the opposite transportation of these ions occur.

19
Q

how is O2 delivered to the tissue from BRCs?

A

the partial pressure of Oxygen is greating in tissues than in the RBCs, so oxygen is released from Hb, forming deoxyhemoglobin.

20
Q

how are CO2 and O2 exchanged in the lungs?

A

the partial pressure of O2 is greater in the alveolar airspace that in the alveoli of the lung than in the capillaries; therefore O2 enters the alveolar airspace cia simple diffusion.

o2 enters the erythrocyte cytosol and bonds to the heme moiety of hemoglobin to form oxyhemoglobin.

bicarbonate ions from the plasma enter the RBC cytosol and chloride ions leave (reversal of the chloride shift)

the bicarbonate ion is combined with H+ ions to form H2CO3 (carbonic acid), which is cleaved by carbonic anhydrase to from CO2 and H2O.

the CO2 enters the plasma and from there the alveolar airspace wia simple diffusion to be exhaled.

21
Q

why is carbon monoxide toxic?

A

carbon monoxide, is inhaled in sufficient amounts, can cause carbon monoxide asphyxiation. the CO bonds avidly to Hb blocking the binding of O2.

22
Q

blood constituents: what are leukocytes? what are the types of WBCs?

A

leukocytes or white blood cells posess a varying number of azurophile granules. these lysosomes containing various hydrolytic enzymes determining the type of WBC they are.

  1. granulocytes: neutrophiles, eosinophils and basophils
  2. agranulocytes: lymphocytes and monocytes
23
Q

blood constiuents: what are granulocytes?

A

granulocytes are a type of leukocyte. they include neutrophils, eosinophils and basophils

  • granulocytes possess specific granules with type-specific contents
  • granulocytes generate ATP via glycolytic pathway, krebs cycle (basophils) and anaerobic pathways (neutrophils)
24
Q

blood constiuents: what two ways do neutrophils destroy phagocytosed microorganisms?

A
  1. azurophilic granules release hydrolytic enzymes into phagosomes to destroy microorganisms
  2. reactive o2 compounds formed within phagosomes destroy microorganisms
25
Q

blood constiuents: what are agranulocytes?

what are the types of lymphocytes?

A

agranulocytes lack specific granules
they include lymphocytes and monocytes

lymphocytes are of 3 types:

  1. B lymphocytes: humpral immune system
  2. T lymphocytes: cellular immune system
  3. Null Cells: 5% of circulating lymphocytes
    - pleuripotential hemopoietic stem cells
    - natural killer cells (NK)
26
Q

blood constiuents: What are the characteristics of neutrophils?

A

neutrophils is a type of granulocyte
neutrophils have a lobulated nucleus (3-4 lobes)
neutrophils contain many azurophilic granules
neutrophils are small and stain light pink.
neutrophil has a life span of 1 week
neutrophil form hydrogen peroxide during phagocytosis

main function is to phagocytose, kill and digest bacteria

27
Q

blood constiuents: what are the characteristics of eosinophils?

A

eosinophils have a bilobed nucleus and contain a few azurophilic granules

eosinophils are large and stain dark pink
eosinophils stay in blood for a few hours before migrating into connetive tissue

main function is to moderate inflammatory reactions by inactivating histamine and leukotriene C

28
Q

blood constiuents: what are the characteristics of basophils?

A

basophils have a nucleus that are S-shaped
basophils contain few azurophilic granules
basophils are large and stain dark blue/black
basophils have a very long life span

main function is to mediate inflammatory responses in a manner similar to mast cells

have receptors for immunoglobulin E on their plasma membrane

29
Q

blood constiuents: what are platelets?

A

platelets or thrombocytes are anucleated disk-shaped cell fragments that arise from megakaryocytes in the bone marrow.

two regions of platelets are visible in stained blood smears. a clear peripheral region (hyalomere) and a region containing purple granules (granulomere

platelets are surrounded by a glycocalyx, which coats the plasmalemma. calcium ions and ADP increase the stickiness of the glycocalyx and enhance platelet adherence.

platelets function in blood coagulation by aggregating at lesions in vessel walls and producing various factors that aid in clot formation

platelets are responsible for clot retraction and clot removal.

30
Q

blood constiuents: what is the granulomere?

A

the region in platelets containing granules visible in stained blood smears

31
Q

blood constiuents: what is the hyalomere?

A

the hyalomere is the clear peripheral region of platelets visible in stained blood smears.

32
Q

blood constiuents: what is the glycocalyx?

A

the glycocalyx surrounds each platelet and coats the plasmalemma. calcium ions and ADP increase the stickiness of the glycocalyx and enhance platelet adherence.

33
Q

what are the two types of bone marrow?

A

yellow marrow

red marrow

34
Q

what is yellow marrow?

A

yellow marrow is located in the long bones of adults and is highly infiltrated with fat.
yellow marrow is not hemopoietic but has the potential to become so

35
Q

what is red marrow?
located…
consists of…
function…

A

red marrow is located in the epiphyses of long bones and in flat, irregular and short bones.

red marrow is highly vascular and composed of a stroma, irregular sinusoids and islands of hemopoietic cells

red marrow is the site of blood cell differentiation and maturation. the largest cells of bone marrow are the megakaryocytes, precursors of platelets.

36
Q

in red marrow, what are sinusoids?

A

sinusoids are large vessels with highly attenuated (thin) endothelia. they are associated on their extravascular surfaces with reticular fibres and adventitial reticular cells, which manufacture these fibres.

37
Q

in red marrow, what is the stroma?

what cells does it contain?

A

the stroma is composed of stromal cells, which include:
- macrophages, adventitial reticular cells, fibroblasts and endothelial cells.
these cells produce and release various hemopoietic growth factors
- macrophages are located in extravascular areas near the sinusoids and extend processes between endothelial cells into the sinusoid lumen
- adventitial reticular cells are believed to subdivide the bone marrow cavity into smaller compartments, whcih are occupied by islands of hemopoietic cells. they may accumulate fate, thus transforming red marrow to yellow marrow

38
Q

in what order of location does prenatal hemopoiesis occur?

A
  1. yolk sac
  2. liver
  3. spleen
  4. bone marrow
39
Q

when does hemopoiesis start in bone marrow?

A

from the 6 month of gestation bone marrow first participates in hemopoiesis and assumes an increasingly large role.

liver and spleen cease hemopoiesis at about the time of birth

40
Q

what proteins are associated with erythrocyte plasma membrane responsible for maintaining the cells biconcave disk shape?

A

spectrin

-aswell as actin

41
Q

what is derived from CFU-Meg?

A

platelets are derived from CFU-Meg

Histology (16 decks)

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