Flashcards in March 3, 2015 --> Cards 16-30 Deck (83):
3 functions of blood
In a blood sample, what is the hematocrit
The percentage of erythrocytes in a blood sample
In males, average hematocrit is what? Females?
Males: 45% hematocrit
Females: 40% hematocrit
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
How is serum different from plasma?
Serum lacks fibrin and other coagulation products
In a blood sample, what is the plasma?
The blood minus the formed elements. It is the fluid portion of the blood
What percentage of blood does plasma make up
55% of blood
T or F, Plasma contains no cells
What three things make up plasma
Proteins (7%) - albumins, globulins and fibrinogen
Other solutes (2%) - hormones, ions, food materials, respiratory gases
If plasma makes up 55% of blood, what makes up the other 45%?
Erythrocytes, leukocytes and thrombocytes (platelets)
In Hemostasis, the circulatory system guards against excessive blood loss. The vascular injury activates what chain of events?
2. Platelet aggregation
**This leads to clotting
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.
They only protease of the extrinsic pathway is what?
factor VIIa, which is formed from the inactive factor VII by thrombin on factor X
Factor VIIa is only active in the presence of what?
2nd step of blood clotting?
Prothrombin activator acts enzymatically to catalyze the formation of thrombin (Factor IIa) from prothrombin (Factor II)
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.
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
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
Production of RBC
Liquid separating from a gel due to further solidification or coagulation
In cirrhosis of the liver, what is deficient
Prothrombin and Fibrinogen levels
What catalyzes reaction of Fibrinogen to fibrin
What pathway has Tissue factor?
It is not present in the blood
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
Iron is absorbed almost entirely in what part of the GI?
the upper part of the small intestine, primarily in the duodenum
What happens to the iron immediately after it is absorbed?
Immediately combines in the blood plasma with a beta globulin APOTRANSFERRIN, to form TRANSFERRIN
Approximately 60% of excess iron is stored where?
in the liver
Iron is stored as what structure?
Iron stored in ferritin is called storage iron
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+)
What is the product of heme degradation?
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
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.
In what chemical form is iron stored as?
If you have A blood type, what antigens and antibodies are present?
**(If antibody anti-A were present, it would attack their own blood)
O blood type has what antigens and antibodies?
Both Antibody Anti-A and Antibody Anti-B
AB blood type has what antigens and antibodies?
Both Antigens A & B
Occurs when blood types are mismatched
T or F, Heme binds oxygen with a greater affinity than carbon monoxide (CO)
False, Binds CO with a greater affinity
What makes up the globin in hemoglobin
2 alpha chains
2 beta chains
What is Hb A?
What is Hb F?
Characteristic of Hb C and what causes it?
Lysine replaces glutamate
Characteristic of Hb H? what causes it
Defect of alpha-chain genes. Composed of 4 B-chains
Characteristic of Hb M? What causes it?
Tyrosine replaces Histidine
Characteristic of Hb S? What causes it?
Valine replaces glutamate in beta chain
Which structure is considered a storage of oxygen
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)
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.
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.
What 4 things can make the oxyhemoglobin dissociation curve shift to the right
Increased hydrogen ions (decreased pH)
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
In which state is iron in within the heme?
The reduced state (Fe2+ or ferrous iron)
A hemoglobin molecule can potentially associate with how many oxygen molecules?
Difference between oxyhemoglobin and deoxyhemoglobin
Oxyhemoglobin: Hb with oxygen
Deoxyhemoglobin: Hb without oxygen
What portion of the hemoglobin does carbon dioxide bind?
Combines reversibly with Co2 at the protein portion of the Hb molecule
as pH decreases, what happens to the affinity of hemoglobin for oxygen?
It also decreases
Which state is iron in Methemoglobin?
Ferric state (Fe3+)
Cannot function as an oxygen carrier
The principle stimulus for RBC production in low oxygen states is what?
The circulating hormone called erythropoietin (glycoprotein)
T or F, Production of erythropoietin and thus erythrocytes, is regulated by a positive feedback mechanism
False, Negative-feedback mechanism
Inadequate erythropoiesis leads to what?
Anemia, increased CO and hypoxia
T or F, Anemic individuals have normal oxygen tension but reduced oxygen content in their systemic arterial blood
Life span of erythrocytes
105 to 120 days
Basic characteristics of Erythrocytes
Lack nuclei and mitochondria
What is carbonic anhydrase?
Converts carbon dioxide and water to bicarbonate and proteins
Role of Intrinsic factor?
essential for absorption of vitamin B12 in the ileum
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)
Oxyntic glands secrete what?
HCL, Pepsinogen, intrinsic factor and mucus
Pyloric glands secrete mainly what?
Mucus but also the hormone gastrin
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
Secretion of what is the only gastric function that is essential for human life
Stomach emptying is enhanced by what 2 things?
Food in the stomach and gastrin
What two signals are used by the small intestine to slow secretion and motility of the stomach
nervous (enterogastric reflex)
endocrine ( CCk, secretin)
What two hormones are released to suppress gastric activity
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
2 major types of contractions in the GI tract
3 signaling molecules important for pancreatic secretion
1. Acetylcholine (released from PNS vagus nerve endings
Which two signaling molecules stimulate production of pancreatic digestive enzymes?
Acetylcholine and Cholecystokinin
What signaling molecule stimulates production of water solution of sodium bicarbonate?
Pancreatic enzymes are secreted in what form?
An inactive form called a zymogen
Pancreatic duct cells secrete a fluid that is high in what?
Where is bile produced and stored?
By the liver and stored in the gallbladder
Gastric empyting is fastest when?
When its contents are isotonic
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)