Download Blood - Laura Banks

Unit 10: Blood
Composition of blood
 Only fluid connective tissue
 It has both solid and liquid components
Living components of blood
 Living blood cells are called formed elements
 45% of blood
Non-living components of blood
 Nonliving fluid matrix is called plasma
 55% of blood
Physical characteristics of blood
 Sticky opaque fluid
 Metallic taste due to the salts
 The brighter the color the more oxygen-rich
 pH of 7.35 to 7.45
 8% of human body weight
Plasma
 The non-living aspect of blood
 90% water
 10% salts and proteins
Function of plasma
 Transport various substances around the body
 Helps distribute body heat evenly throughout the body
Plasma continued
DO NOT WRITE:
 There are various constituents of plasma (things that make
plasma up)
 The following section is the list of key constituents within
plasma, and their specific role in the body
Water
 Solvent for carrying other substances
Salts (electrolytes)
 Osmotic balance
 pH buffering
 Regulation of membrane permeability
Plasma Proteins
 Osmotic balance
 pH buffering
 Blood clotting
 Defense
 Lipid transport
Substances transported by blood
 Nutrients
 Waste products from metabolism
 Respiratory gases
Formed Elements
What are formed elements?
 Blood cells and platelets
 LIVING constituents of blood
Erythrocytes
Aka: Red Blood Cells
 ~ 4-6 million per mm3
 Function: carry oxygen to all cells in the body
Anatomy of Erythrocytes
 Lack a nucleus and contains very few organelles
 sacs of hemoglobin, an iron containing protein
 More hemoglobin = better oxygen transport
Shape of erythrocytes
 Bulky outer ring with a depressed center
 biconcave
 This depression helps carry oxygen
Leukocytes
Aka: White Blood Cells
 ~4,000 to 11,000 per mm3
 Critical to body defenses against disease caused by bacteria,
viruses, parasites, and tumors
Anatomy of Leukocytes
 Only blood cell to contain nuclei and organelles
 Because there are various types of WBC, there is no general
shape
How do they function in the blood?
 WBC’s can jump from the blood stream to the other organs
in order to carry out their function
 They use this method for inflammatory and immune
responses
How do WBC’s know where to go?
 By a process is called positive chemotaxis
 When cells are damaged or destroyed, they release the
chemicals within them
 The WBC’s are able to locate this chemical and seek it out
Neutrophils:
 40-70% of WBC
 Active phagocytes
 # increases rapidly during acute infections
Eosinophils:
 1-4% of WBC
 Kill parasitic worms, increase during allergy attacks
Basophils:
 0-1% of WBC
 Contains histamine, discharged at sites of inflammation
Lymphocytes:
 20-40% of WBC
 B-lymphocytes – produce antibodies
 T-lymphocytes- graft rejection, fighting tumors & viruses
Monocytes
 4-8% of WBC
 Become macrophages
 Long term “clean-up team”
Platelets
 ~300,000 per mm3
 They are actually incomplete pieces of cells
 They function in blood clotting
What are platelets made out of?
 A complex, multinucleate cell ruptures and releases
thousands of fragments of itself
 Once they explode, they attempt to reattach to each other
 Forms a net that blood may clot onto
Hematopoiesis
 blood cell formation
 Occurs in bone marrow of long bones
 Once finished, the new blood cells are released into the
surrounding blood vessels
What causes hematopoiesis?
 Each blood type is produced in response to changing stimuli
 Effects for each blood cell type and platelets will be looked at
Before hematopoiesis:
 Stem cells* called hemocytoblasts are found in the bone
marrow of bones
 These cells are activated by specific hormones which
determine what type of cell it will become
 *A stem cell is a cell that can become any type of cell
initially. Once its path is set, however, it MUST become what
has been determined.
 For example, a hemocytoblast is activated to become a RBC,
once this happens, it can never be a WBC or platelet
Hematopoiesis of Erythrocytes
Why cant RBC’s just split to make new
cells?
 RBC’s are anucleate, so they cannot repair, grow, or divide
 As they age, they become rigid and fall apart
 Life expectancy of RBC: 100-120 days
What happens to old RBC’s?
 Remains of old and broken RBC’s are eliminated by
phagocytes in the body
How does the body replace the old
RBC’s?
 Hematopoiesis
 This replaces the RBC’s continuously throughout life
 This occurs over a 4-step process
Step 1: stimulus
 Decreased RBC count
 Decreased availability of O2 to blood
 Increased tissue demands for O2
 all these lead to decreased O2 levels in blood
Step 2:
 Kidneys release the hormone erythropoietin
Step 3
 Increased levels of erythropoietin stimulates the bone
marrow to increase production of RBC’s
Step 4
 The increased RBC count raises the amount of O2 distributed
to the blood and tissues
 Homeostasis is restored
Hematopoiesis of Leukocytes
How does hematopoiesis of WBC’s
occur?
 The exact same way as for RBC’s, with only 2 changes:
WBC hematopoiesis
1. The new stimuli are chemicals released when cells are
inflamed or destroyed, as well as exposure to bacteria and
toxins
WBC hematopoiesis continued
2. The hormones that stimulate the bone marrow to produce
WBC’s are called interleukins
What is hemostasis?
 stoppage of blood flow
 It occurs after a blood vessel is broken
Phases of Hemostasis
 3 phase process that completely stops blood loss and fills the
hole in the blood vessel
phase 1: Vascular Spasms
 Damage occurs which spreads platelets out.
 Once platelets spread, they become sticky and attach to the
damage site
 The platelets then release chemicals to attract other platelets,
and to induce spasms of the blood vessel
 Constricts the blood vessels and reduces blood loss
phase 2: Platelet Plug Formation
 Once the platelets have attracted enough of each other onto
the damaged tissue, a plug of platelets is formed
 This prevents blood loss, but is very weak and easily broken
phase 3: Coagulation
 Threadlike proteins called fibrin then connect the edges of
the ruptured blood vessel to begin the healing process.
 This occurs OVER the platelet plug
How long does this process take?
 Blood clotting usually takes only 3-6 minutes
What happens after the clot is formed?
 Immediately after the clot forms, the healing factors are
disabled
 This prevents too much blood from clotting, which can lead
to strokes
 The extra clot is then broken down
Blood Types
Why do we have different blood types?
 Our RBCs have different molecules attached to them
 Each person’s molecules are unique
 These molecules are called antigens
Antigens
o Molecules that, when introduced into the body, triggers the
immune system to kill the new antigen
 Our bodies naturally produce some antigens, they are found
on our RBCs
 Since we all have different antigens on our RBCs, our bodies
can tolerate our own blood, but certain blood types are lethal
to other people.
Are all foreign antigens lethal to us
then?
 There are only 3 main RBC antigens that are lethal to us:
 Antigen A
 Antigen B
 Rh antigen
 The occurrence of these antigens in our blood determine
what blood type we are
How does our body fight the antigens?
 Anti-A and Anti-B antibodies are located in the plasma
 Anti-A antibodies will destroy RBCs with A antigens
 Anti-B antibodies will destroy RBCs with B antigens
Blood group types
 4 types based off the A and B antigens located on the RBCs
Type 1: AB
 This blood type has both A and B antigens
 Therefore, there are NO antibodies in the plasma
 This blood type may receive A, B, AB, and O type blood
 Universal reciever
Type 2: B
 This blood type has only B antigens
 Therefore, there are anti-A antibodies in the plasma
 This blood type may receive B and O type blood
Type 3: A
 This blood type has only A antigens
 Therefore, there are anti-B antibodies in the plasma
 This blood type may receive A and O type blood
Type 4: O
 This blood type has NO antigens
 Therefore, there are anti-A and anti-B antibodies in the
plasma
 This blood type may receive only O blood type
 Universal donor
Rh factor
 Rh is a different type of antigen that is NOT produced
naturally by the blood of Rh negative people
 The immune system produces Rh antibodies only when
exposed to the Rh antigen
How do we receive the Rh antigen?
 The Rh antigens are passed down genetically
 Rh antibodies are made by our immune system when
exposed to the Rh antigen
 This is the + or – sign you see in your blood type