Transcript A&P 2 - Blood

Blood
Blood Characteristics
Stats:
Connective tissue
Volume : 4-6L
pH: 7.35-7.45
Temp: 38oC or 100.4 oF
Components:
Plasma – 55%
Erythrocytes – 45%
Leukocytes/Platelets <1%
Functions:
Transport – of hormone,
gases, nutrients, etc
Regulation – of pH, body
temp, water balance
Protection – from blood
loss and infection
Figure 17.1
Plasma
Plasma – the liquid component of blood
Components:
• Water – 90% of volume
• Plasma proteins – 8% of volume
- Most produced by liver
- Albumin – most abundant protein
(60%), a transport protein
- Globulins (36%) – transport
proteins and antibodies
- Fibrinogen (4%) – clotting protein
• Nonprotein solutes
- Nitrogenous wastes
- Electrolytes
- Respiratory gases
- Hormones
Table 17.1
Formed Elements
Formed Elements – the
cellular components of blood
1. Erythrocytes- red blood
cells
2. Leukocytes – white blood
cells
3. Thrombocytes - platelets
Figure 17.2
Erythrocytes
Erythrocytes – red blood cells
• Number – 5M/ µL
• Diameter: 7.5 µm
• Shape – biconcave, increases SA
• Anucleate – lack a nucleus at
maturity
• Functions – oxygen and carbon
dioxide transport
Figure 17.3
Hemoglobin
• Hemoglobin (Hb) - Protein composing 97% of RBC volume
• Globin – amino acid-based portion with 2 alpha chains,2 beta chains
• Heme – pigment portion with a central Iron atom. 4, one per globin chain
• 4 heme = 4 oxygen x 250M Hb/RBC = 1B oxygen/RBC!
• Variations – oxyhemoglobin, deoxyhemoglobin, carbaminohemoglobin
Figure 17.4
Erythropoeisis
Hematopoiesis – blood cell formation, occurs in red bone marrow
Erythropoiesis – red blood cell production
- all blood cells arise from a common stem cell, a hemocytoblast
- after Hb accumulates, the nucleus and organelles beak down
- Now reticulocytes, they enter the bloodstream and become
mature RBC’s
Erythropoietin (EPO) – hormone that triggers RBC production
Figure 17.5
Regulating Erythropoesis
1. Low blood oxygen
levels triggers
erythropoietin (EPO)
release from the
kidneys
2. EPO causes activity of
red bone marrow
3. RBC count rises
4. Blood oxygen levels
rise, inhibiting EPO
release
Raw Materials – amino acids, lipids,
carbohydrates, Iron, and vitamin B
Figure 17.6
Erythrocyte Breakdown
• Lifespan – circulate for 100 - 120 days
• Breakdown – RBC’s engulfed by
macrophages in liver, spleen, and bone
marrow
Hemoglobin breakdown
1. Hemoglobin is split into heme and
globin
2. Globin’s amino acids are recycled to the
blood
3. Heme’s iron is stored in the liver for
future use
4. Heme’s pigment, now bilirubin, is used
in bile production
Figure 17.7
Erythrocyte Disorders
Anemia – any condition leading to a lowered oxygen carrying capacity of the blood
- Hemorrhagic anemia – due to blood loss
- Hemolytic anemia – due to RBC rupture
- Iron-deficiency anemia – unable to build RBC’s
- Sickle-cell anemia – a genetic mutation leading to malformed Hb
Polycythemia – an abnormally high RBC count, 6+ M cells/µL, resulting from bone
marrow cancer or high elevations
Figure 17.8
Leukocytes
Leukocytes – white blood cells
• Number: 5,000-10,000 cells/µL
• Possess nuclei and organelles
• Function – immune responses
• Diapedesis – ability of WBC’s to
exit capillaries and enter tissues
• Leukocytosis – WBC count >
11,000 cells/µL, a sign of infection
Remembering WBC count: Never Let Monkeys Eat Bananas
Figure 17.9
Leukocytes
Granulocytes – WBC’s with cytoplasmic granules
- Neutrophils, Eosinophils, and Basophils
Agranulocytes – WBC’s without granules
- Lymphocytes and Monocytes
Figure 17.10
Neutrophils
Neutrophils:
• Most abundant leukocyte,
50-70% of WBC’s, count
rises during bacterial
infection
• Function – phagocytes of
bacteria, fungi, etc.
• ‘First responders’ to a site
of inflammation
• Multilobed nucleus
• Granules contain enzymes
and antimicrobial proteins
Figure 17.10a
Eosinophils
Eosinophils:
• 2-4% of WBC’s, count rises
during parasitic infection
• two-lobed nucleus
• granules contain digestive
enzymes specific to parasitic
worms
Figure 17.10b
Basophils
Basophils:
• Rarest leukocyte, 0.5-1% of
WBC’s
• Granules contain histamine, an
inflammatory chemical
• Play a role in allergic reactions
Figure 17.10c
Lymphocytes
Lymphocytes
• 25-45 % of WBC’s
• Large nucleus and little cytoplasm
• Many located outside vessels, in
lymph nodes, spleen, etc.
• Two main types:
- T cells – target virally-infected cells
- B cells – make antibodies
Figure 17.10d
Monocytes
Monocytes:
• 3-8% of WBC’s
• Largest WBC, 14-24 µm
• Migrate into tissues where they
become macrophages, long-lived
phagocytes
Figure 17.10e
Leukopoiesis
Leukopoiesis – the production of
WBC’s
• all arise from hemocytoblast stem
cell
• Lymphoid cell line produces only
lymphocytes
• Myeloid cell line produces all other
WBC’s and RBC’s
• Stimulated by inflammatory
chemicals
Figure 17.11
Platelets
Platelets:
• Cytoplasmic fragments of marrow cells called megakaryocytes
• Promote clotting by forming a temporary plug in a damaged vessel wall
• Only circulate for 10 days, are constantly produced
Figure 17.12
Hemostasis
Hemostasis – the stoppage of bleeding
Occurs in 3 steps:
1. Vascular Spasm – constriction of the
damaged vessel to limit blood loss
2. Platelet plug formation – platelets stick to
the exposed collagen fibers of a damaged
blood vessel, become sticky, and chemically
recruit more platelets to form a plug
3. Coagulation – blood clotting, which occurs
in three steps
Figure 17.13a
Coagulation
Coagulation – a complex chemical process
involving calcium and a balance of
procoagulants and anticoagulants in 3 steps
1. Forming Prothrombin Activator – must
form this enzyme to catalyze step 2
- Intrinsic pathway – slower, all
components from within blood
- Extrinsic pathway – faster, uses TF
from damaged tissue
2. Thrombin formation – Prothrombin
activator converts prothrombin to
thrombin
3. Fibrin formation – Thrombin converts
soluble fibrinogen into solid fibrin strands,
which stick to form the clot
Figure 17.13b
Hemostasis
Clot retraction – the tightening of
a clot within 30-60 minutes
Fibrinolysis – the breakdown of a
blood clot, performed by plasmin
enzyme
Anticoagulants – prevent
overclotting by deactivating
thrombin. Ex’s - Antithrombin III and
Heparin
Figure 17.14
Disorders of Hemostasis
Clotting Disorders:
• Thrombus – a blood clot in an
undamaged vessel
• Embolus – a blood clot floating
freely in the bloodstream
• Embolism – a circulating blood
clot that has blocked a vessel
• Aspirin and Heparin are used to
prevent and treat these clots
Bleeding Disorders:
• Hemophilia – various hereditary
conditions resulting in the lack of
certain procoagulants
• Thrombocytopenia – low platelet
levels
Figure 17.14
Blood Groups
ABO blood groups – blood types according to proteins on the
RBC cell surfaces
Genes – A,B, and O genes encode for A, B, and O proteins .
Every person possesses two of these genes
Table 17.4
Blood Groups
Agglutinogens – the proteins on the RBC surfaces
Agglutinins – antibodies specific to the agglutinogens not possessed by an
individual
Agglutination – the clumping of cells that occur when agglutinins bind to
their specific agglutinogens
Table 17.4
Blood Groups
Blood Typing:
• Split a blood sample into two
halves
• Mix one half with a serum of A
agglutinins and the other with a
serum of B agglutinins
• Any sample that clumps
(agglutinates) shows you that
specific agglutinogen is present
on the RBC surfaces
Figure 17.15
Blood Groups
Blood Type
A
B
AB
O
Genes
Agglutinins
Donate To
Receive
From
Blood Groups
Rh blood groups:
• Classifies blood type as + or –, based on the presence or
absence of an RBC surface protein
• +,+ = a positive blood type
• +, - = a positive blood type
• -, - = a negative blood type
• An Rh+ person can safely receive Rh- blood, but an Rhperson receiving Rh+ blood will cause agglutination…Why?
• Erythroblastosis Fetalis – when an Rh- mother’s immune
system rejects the Rh+ blood of her fetus. Does not happen if
it her first pregnancy…Why?