March 3, 2015 --> Cards 16-30 Flashcards Preview

BOARD: Biochemistry (Dental Decks) > March 3, 2015 --> Cards 16-30 > Flashcards

Flashcards in March 3, 2015 --> Cards 16-30 Deck (83):
1

3 functions of blood

Transportation
Buffering
Thermoregulation

2

In a blood sample, what is the hematocrit

The percentage of erythrocytes in a blood sample

3

In males, average hematocrit is what? Females?

Males: 45% hematocrit
Females: 40% hematocrit

4

What is the serum in blood?

The clear, thin, and sticky fluid portion of the blood obtained after removal of the fibrin clot and blood cells

5

How is serum different from plasma?

Serum lacks fibrin and other coagulation products

6

In a blood sample, what is the plasma?

The blood minus the formed elements. It is the fluid portion of the blood

7

What percentage of blood does plasma make up

55% of blood

8

T or F, Plasma contains no cells

True

9

What three things make up plasma

Proteins (7%) - albumins, globulins and fibrinogen
Water (91%)
Other solutes (2%) - hormones, ions, food materials, respiratory gases

10

If plasma makes up 55% of blood, what makes up the other 45%?

Erythrocytes, leukocytes and thrombocytes (platelets)

11

In Hemostasis, the circulatory system guards against excessive blood loss. The vascular injury activates what chain of events?

1. Vasoconstriction
2. Platelet aggregation
3. Coagulation
**This leads to clotting

12

1st step of blood clotting

Production of thrombin from prothrombin during the clotting process REQUIRES A PROTHROMBIN ACTIVATOR, which is formed either by way of an extrinsic pathway or by way of an intrinsic pathway.

13

They only protease of the extrinsic pathway is what?

factor VIIa, which is formed from the inactive factor VII by thrombin on factor X

14

Factor VIIa is only active in the presence of what?

Tissue factor

15

2nd step of blood clotting?

Prothrombin activator acts enzymatically to catalyze the formation of thrombin (Factor IIa) from prothrombin (Factor II)

16

3rd step of blood clotting

Thrombin (Factor IIa) acts as an enzyme to convert fibrinogen (Factor I) into fibrin (Factor Ia) threads that enmesh red blood cells and platelets to form the clot itself.

17

When blood vessels are ruptured and tissues are damaged, which of the blood clotting pathways are activated?

Both extrinsic and intrinsic pathways are usually activated

18

In what disorder does prothrombin and fibrinogen levels that are deficient cause impaired clot formation?

Cirrhosis of the liver
REMEMBER: liver synthesizes factors II, VII, IX, and X

19

Define Erythropoiesis

Production of RBC

20

Define Syneresis

Liquid separating from a gel due to further solidification or coagulation

21

In cirrhosis of the liver, what is deficient

Prothrombin and Fibrinogen levels

22

What catalyzes reaction of Fibrinogen to fibrin

Thrombin

23

What pathway has Tissue factor?

Extrinsic pathway
It is not present in the blood

24

The 15 to 25% of iron that is stored in the liver, spleen and bone marrow, are mainly in what forms?

Iron-protein complexes called:
Ferritin and Hemosiderin

25

Iron is absorbed almost entirely in what part of the GI?

the upper part of the small intestine, primarily in the duodenum

26

What happens to the iron immediately after it is absorbed?

Immediately combines in the blood plasma with a beta globulin APOTRANSFERRIN, to form TRANSFERRIN

27

Approximately 60% of excess iron is stored where?

in the liver

28

Iron is stored as what structure?

Iron stored in ferritin is called storage iron

29

Why do reducing agents in food such as ascorbate (Vitamin C) promote iron uptake?

Iron can only be absorbed by the bowel in bivalent form (as Fe2+)

30

What is the product of heme degradation?

Bilirubin

31

What is Hemochromatosis

An iron-storage disease that results in the deposition of iron-containing pigments in the peripheral tissues with characteristic bronzing of the skin, diabetes and weakness

32

What is the dominant factor controlling absorption of iron from the GI tract is what?

The Saturation of mucosal cells with iron particularly dictated by the rate at which the transferrin complex is able to exit the epithelial cell into the vascular system.

33

In what chemical form is iron stored as?

Fe3+

34

If you have A blood type, what antigens and antibodies are present?

Antigen A
Antibody Anti-B
**(If antibody anti-A were present, it would attack their own blood)

35

O blood type has what antigens and antibodies?

No antigens
Both Antibody Anti-A and Antibody Anti-B

36

AB blood type has what antigens and antibodies?

Both Antigens A & B
No Antibodies

37

Define Hemagglutination

Occurs when blood types are mismatched

38

T or F, Heme binds oxygen with a greater affinity than carbon monoxide (CO)

False, Binds CO with a greater affinity

39

What makes up the globin in hemoglobin

2 alpha chains
2 beta chains

40

What is Hb A?
What is Hb F?

Normal hemoglobin
Fetal hemoglobin

41

Characteristic of Hb C and what causes it?

Chronic anemia
Lysine replaces glutamate

42

Characteristic of Hb H? what causes it

alpha-thalassemia
Defect of alpha-chain genes. Composed of 4 B-chains

43

Characteristic of Hb M? What causes it?

Methmoglobinemia
Tyrosine replaces Histidine

44

Characteristic of Hb S? What causes it?

Sickle-cell anemia
Valine replaces glutamate in beta chain

45

Which structure is considered a storage of oxygen

Myoglobin

46

What are the the two conformation states of hemoglobin

Tense (T) or Relaxed (R)
T: weaker affinity for oxygen (Capillaries)
R: stronger affinity for oxygen (lungs)

47

What determines whether Hb binds with or releases O2

-Depends in large part on the oxygen partial pressure.

-When the PO2 is relatively high (Pulmonary capillaries), Hb has a higher affinity for O2 and is 98% saturated.

- At a lower PO2 (tissue capillaries), Hb has a lower affinity for O2 and is only partially saturated.

48

An oxyhemoglobin dissociation curve can be shifted to the right when what occurs?

When the affinity of Hgb for O2 decreases, which enhances O2 dissociation.

When the affinity of Hgb for O2 increases, the curve is shifted to the left, which reduces the P50. In this state O2 dissociation and delivery to tissues are inhibited.

49

What 4 things can make the oxyhemoglobin dissociation curve shift to the right

Increased hydrogen ions (decreased pH)
Increased CO2
Increased temperature
Increased BPG

50

Normal fetal globin portion of Hb consists of what 4 chains? Is this different than normal Hb

It consists of 2 alpha and 2 gamma chains
**Different from normal hemoglobin that that has 2 alpha and 2 beta chains

51

In which state is iron in within the heme?

The reduced state (Fe2+ or ferrous iron)

52

A hemoglobin molecule can potentially associate with how many oxygen molecules?

4

53

Difference between oxyhemoglobin and deoxyhemoglobin

Oxyhemoglobin: Hb with oxygen
Deoxyhemoglobin: Hb without oxygen

54

What portion of the hemoglobin does carbon dioxide bind?

Combines reversibly with Co2 at the protein portion of the Hb molecule

55

as pH decreases, what happens to the affinity of hemoglobin for oxygen?

It also decreases

56

Which state is iron in Methemoglobin?

Ferric state (Fe3+)
Cannot function as an oxygen carrier

57

The principle stimulus for RBC production in low oxygen states is what?

The circulating hormone called erythropoietin (glycoprotein)

58

T or F, Production of erythropoietin and thus erythrocytes, is regulated by a positive feedback mechanism

False, Negative-feedback mechanism

59

Inadequate erythropoiesis leads to what?

Anemia, increased CO and hypoxia

60

T or F, Anemic individuals have normal oxygen tension but reduced oxygen content in their systemic arterial blood

True

61

Life span of erythrocytes

105 to 120 days

62

Basic characteristics of Erythrocytes

Biconcave
Lack nuclei and mitochondria

63

What is carbonic anhydrase?

Converts carbon dioxide and water to bicarbonate and proteins

64

Role of Intrinsic factor?

essential for absorption of vitamin B12 in the ileum

65

Gastric mucosa of stomach is divided into three distinct regions based on the structure of the glands? What are they

1. Small cardiac glandular region, just below lower esophageal sphincter) contains mucus-secreting gland cells
2. Oxyntic or parietal (Gastric glands)
3. Pyloric

66

Oxyntic glands secrete what?

HCL, Pepsinogen, intrinsic factor and mucus

67

Pyloric glands secrete mainly what?

Mucus but also the hormone gastrin

68

Oxyntic gland is composed of what 3 main types of cells?

1. Mucous neck cells (secrete mucus)
2. Peptic (Chief) cells (secrete pepsinogen)
3. Parietal cells (secrete HCL & intrinsic factor

69

Secretion of what is the only gastric function that is essential for human life

Intrinsic factor

70

Stomach emptying is enhanced by what 2 things?

Food in the stomach and gastrin

71

What two signals are used by the small intestine to slow secretion and motility of the stomach

nervous (enterogastric reflex)
endocrine ( CCk, secretin)

72

What two hormones are released to suppress gastric activity

CCK
Secretin

73

In general, what does sympathetic stimulation do to the GI secretion and motor activity?

It causes inhibition of gastrointestinal secretion and motor activity, and inhibits contraction of gastrointestinal sphincters and blood vessels
***Parasympathetic stimuli and ACETYLCHOLINE typically stimulate digestive activities

74

2 major types of contractions in the GI tract

Peristalsis
Mixing contractions

75

3 signaling molecules important for pancreatic secretion

1. Acetylcholine (released from PNS vagus nerve endings
2. Cholecystokinin
3. Secretin

76

Which two signaling molecules stimulate production of pancreatic digestive enzymes?

Acetylcholine and Cholecystokinin

77

What signaling molecule stimulates production of water solution of sodium bicarbonate?

Secretin

78

Pancreatic enzymes are secreted in what form?

An inactive form called a zymogen

79

Pancreatic duct cells secrete a fluid that is high in what?

Bicarbonate ion

80

Where is bile produced and stored?

By the liver and stored in the gallbladder

81

Gastric empyting is fastest when?

When its contents are isotonic

82

Which gastric contents delay gastric emptying?

-Hypertonic or hypotonic contents
-Fat (by stimulating cholecystokinin --> causes receptive relaxation)
-H+ in the duodenum (stimulates neural reflexes to stomach)

83

Dipeptides and amino acids are the end products of protein digestion. The final digestive stage occurs how and by what enzyme?

The brush border peptidases with absorption immediately following
- Absorption across the brush border occurs by multiple secondary active transporters