Blood Cells & Vessels Flashcards
Hematopoiesis
Formation of blood cellular components
Components formed by hematopoiesis
All blood cells
Extracellular components
Blood vessels
Lymphoid tissues (CT)
How much blood do most adults have at a given time?
About 6L of blood
Approx 7-8% of total body weight
Blood
Functions
Transportation throughout the body (O2, waste, CO2) Delivery of hormones Maintain homeostasis Acts as a buffer Acts as a coagulant Participates in thermoregulation
Blood
Components
Cells and their derivatives
Plasma: protein-rich fluid
What are all blood cells derived from?
Hematopoietic stem cells
How many blood cells are formed daily?
10^11 - 10^12
Hematopoietic stem cells
Reside in bone marrow
Give rise to all mature blood types and tissues
Self-renewing
Give rise to myeloid stem cells and lymphoid stem cells
Location of hematopoietic stem cells
Fetal, infants, toddlers: spleen and thymus
Adults: spleen, marrow cavity of long bones
Adult Hematopoietic stem cells
In the red bone marrow (spleen remains active in maturing and differentiating lymphoid cells) Most hematopoietic stem cells in adults resides in: Pelvis Cranial bones Vertebrae Sternum Ribs
Fetal, infants, toddlers hematopoietic stem cells
Located in spleen and thymus
A boarding school for T-cells
When long bones gain medullary cavity, function switches over to there
Myeloid stem cells
Become myeloblasts
Blood cell lineages
Three:
Erythroid cells
Lymphoid cells
Myelocytes (granulocytic lineage)
Erythroid cells
Form RBC’s
Lymphoid cells
Form lymphocytes = WBC’s
Myelocytes
Form granulocytes = WBC’s
Do dipole have marrow?
Yes
Red marrow
(spongy inside compact bone)
Plasma
Composition
Fluid component of blood
90% water, 10% dissolved solutes
3 Main plasma proteins
Lymph nodes
Filter substances that travel through the lymphatic fluid contain lymphocytes (WBC) to fight infections
Main plasma proteins
Three groups:
Albumin
Alpha, beta, and gamma globulins
Fibrinogen
Solutes
Composed of the following: Plasma proteins 7% Inorganic salts 0.9% Organic compounds 2.1% (amino acids, vitamins, hormones) Gases
Albumin
Group of plasma proteins
Largest component
Primary role: maintain blood osmotic pressure
Made by liver
Alpha, beta, and gamma globulins
Group of plasma proteins
Gamma: immunoglobulins (antibodies)
Released by plasma cells (lymphocytes)
Alpha and beta: transport proteins
Made by liver;
fat soluble vitamins
Fibrinogen
Group of plasma proteins Clotting protein Made by liver Circulates in an inactive form (can be activated to form a clot for wound healing)
Lipids
Not soluble
Still may be transported
Bound to hydrophobic portions of transport proteins
Formed elements of blood
Blood cells
Include:
Erythrocytes
Leukocytes
Platelets
Erythrocytes
Red blood cells Biconcave discs (7.5 um) Thin centers appear lighter than edges Small enough to be transported along Anaerobic Anucleate Essentially no organelles
Bags of hemoglobin (gas transport)
Some peripheral proteins line inner sides of plasmalemma (maintain shape and flexibility)
Reticulocytes
Immature RBC’s
Recently released by bone marrow
May show sparse stained granules
Normally comprise 1% of RBC’s
When they mature, they lose their:
Mitochondria, ribosomes, nucleus, etc.
Lifespan of RBC’s
Approx. 120 days
Worn out cells removed by macrophages of spleen
Sickle cell disease
Example of RBC dysfunction Inherited disorder RBC's become flattened from the side Inflexible and fragile Leads to anemia Shortened lifespan
Hematocrit
The volume of packed erythrocytes in a sample of blood
RBC Energy
Energy obtained from glucose
Anaerobic generation of ATP
Leukocytes
WBC’s
Specific and non-specific defense
Involved cellular and humoral defense
Move about in suspension of plasma
Can become motile and exit to the bloodstream
Two classifications: granulocytes and agranulocytes
Rh System
Looks for presence of absence of Rh factor (antigen)
In cell membrane of RBC’s
Important in blood donation and pregnancies
Antigens
Two kinds, A and B
On surface of RBC’s
Antibodies
Are in plamsa
Granulocytes
Classification of leukocytes Polymorphonuclear leukocytes "many shapes of nucleus" Have lobed nuclei Usually pertains to neutrophils
Contain nuclei with two or more lobes and have specific granules that have specific functions
Agranulocytes
Classification of leukocytes
Mononuclear leukocytes
May have lysosomes
Types of granulocytes
Neutrophils
Eosinophils
Basophils
Types of agranuloctes
Lymphocytes
Monocytes
What is the histological hallmark of acute inflammation?
Neutrophil presence
Lots of chemicals
Inflammation is a nasty process to clean up!
They collect in large numbers if something wrong.
Process could be minutes to days
Neutrophils
Type of granulocytes (leukocytes) 60-70% 12-15 um Typically have 3-lobe nucleus Lobes linked by chromatin threads Numerous visible granules Lifespan: 6 hours in bloodstream
Chromatin threads
Link the lobes of nucleus in neutrophils
What cells account for half of WBC’s?
Neutrophils
Immature vs. old neutrophils
Have non-segmented, horse-shoe nuclei
More than five lobes may occur in old neutrophils
Function of Neutrophils
Defense against microorganisms
(motility means they can exit blood stream into CT and act there)
Can phagocytize bacteria and fungi
Kill bacteria with a respiratory burst
“Bacteria specialists” - oxygen used to produce potent substances such as bleach and hydrogen peroxide
Eosinophils
Type of granulocytes (leukocytes)
2-4%
12-15 um
Poorly developed ER, Golgi complex, mitochondria
Contain large, elongate specific granules that contain enzymes (which attack parasites)
They DON’T know speicif antigens, just follow chemical patterns
Can be found in: Underlying CT of skin Bronchi GI tract Uterus Vagina
Lifespan: 8-12 days
Function of Eosinophils
Regulate function of other leukocytes Attack parasitic worms Destroy antigen-antibody complexes Inactivate some inflammatory mediators (reactive leukotrienes and histamine)
Basophils
Type of granulocytes (leukocytes)
0.5%
12-15 um
Numerous granulocytes
Histologically and functionally similar to mast cells
Lifespan: several hours to days
Basophils
Contain granules with histamine and heparin
Can release granules in response to antigens
Mostly seen in bloodstream, but can migrate to CT
Mast cells
Contain granules with histamine and heparin
Can release granules in response to antigens
Only found in CT
Have more oval nuclei
Histamine
Vasodilator
Heparin
Anticoagulant
What has to occur before healing can happen?
Inflammation has to end!
Lymphocytes
Type of agranulocytes Second most numerous leukocytes, 20-30% 5-18 um Spherical nuclei Vary widely in size
Three types:
Natural killer cells (NK cells)
T cells
B cells
Monocytes
Type of agranulocytes
Largest leukocyte in size
12-24 um
Lifespan: hours to days in blood
Live for months as macrophages in CT (important)
Turn over regularly in the blood
Differentiate into larger macrophages
Active in phagocytosis
Require not previous exposure (innate)
Natural killer cells
Type of lymphocyte Large, granular Protect body from tumors Protect body from virally infected cells Release cytotoxic granules
No previous exposure needed (innate)
Lifespan: hours to years
T cells
Type of lymphocyte
Major part of adaptive immune response
Produce antibodies
Shorter lifespan
Involved in direct encounters and collaboration
Differentiate into plasma cells or memory cells
Main player in recognizing something different and targeting it with antibodies
B cells
Type of lymphocyte
Major part of adaptive immune response
Longer lifespan
Differentiate into plasma cells or memory cells
Main player in recognizing something different and targeting it with antibodies
Memory cells
Store info about antigens (like vaccines)
Formed by T and B cells
Macrophages
Great collaborative of immune systems
Phagocytosis
“Collectors”
Doesn’t need exposure (innate)
Platelets
Thrombocytes 2-4 um Annucleate Disc shaped cell fragments Actually fragments of megakaryocytes
Clump together in stains
Lifespan: 5-10 days
Megakaryocytes
Huge myeloid cells
Function of platelets
Active blood clotting Granules contain serotonin (vasoconstrictor) Adenosine diphosphate (attracts more platelets)
Red bone marrow
Components
Contains: Stroma Matrix is collage I & II Glycoproteins (fibronectin, hemonectin) Proteoglycans Hematopoietic stem cells Sinusoids
Stroma
Delicate network of reticular fibers
Contains stem cells and macrophages
Inside red marrow
Sinusoids
In red marrow
Thin endothelia
Mature cells may migrate in at thinnest regions
Functions of red marrow
Produces blood cells
Breaks down old RBC’s
Storage or iron (from hemoglobin)
Yellow bone marrow
Appears yellow as child, due to increased storage of adipose cells
May covert to red marrow (hypoxia and bleeding)
Blood vessels
Development
Develop from blood islands
Central cells form erythrocytes
Peripheral cells flatten and form endothelial lining
Blood islands
Visible patches of condensed mesenchyme
Central cells in them differentiate into erythrocytes
Peripheral cells flatten and form endothelial lining
Heart
Development
Some similarities to blood vessel development
Forms from cariogenic cords that canalize to form a lumen
Once canalized, there are heart tubes
Layers of blood vessels
Tunica intima
Tunica media
Tunica adventitia
Tunica intima
Layer of blood vessels
Endothelium
Simple Squamos Epithelium
In larger vessels, a subendotheliual layer of loose CT connects intima to media
An elastic membrane (internal elastic lamina) may be present
Tunica media
Layer of blood vessels
Mostly circular arrangement of smooth muscle
Elastic fibers in lamellar sheets
Reticular fibers, proteoglycans are present in variable amounts
Vasomotor nerves
Baroreceptors
Tunica adventitia
Layer of blood vessels
Collagen type I and elastic fibers
In larger vessels, vasa vasorum is present here.
Lymphatic capillaries penetrate this layer
Can have external elastic lamina
Lymphatic capillaries
Penetrate the tunica adventitia only in arteries
Greater pressure in arteries could compress lymph vessels
Internal elastic lamina
An elastic membrane that may be present in some arteries
Muscular and elastic
This “smooths out blood pressure level”
Vasomotor nerves
Inside tunica media layer of blood vessels
Sympathetic
Baroreceptors
Inside tunica media layer of blood vessels
Sense pressure
In the aortic arch and carotid sinus
Vasa vasorum
Can be located in tunica adventitia
Tiny vessels that nourish the outermost parts (adventitia, media) of vessels (veins, where oxygen and nutrition levels are low)
External elastic lamina
Can be present in tunica adventitia in some larger arteries (muscular)
May separate media and adventitia
Is thinner than internal elastic lamina
Elastic arteries
Aorta and major branches
Largest amount of elastin
In all three layers, but mostly tunica media
Kept under continuous pressure*
Relatively thin tunica adventitia in large arteries
Muscular arteries
Extension of the elastic arteries Proportionally the thickest tunica media More smooth muscle than elastin It's less elastic Mor vasoconstrictive Has intermediate elastic laminae
Arterioles
General and Function
Very small!
Leads to the front end of capillary bed
Mostly smooth muscle in tunica media
Small ones barely have tunica adventitia
Function:
Vasoconstriction (dictate where blood is)
Capillaries
General
A little larger than arterioles Just enough for erythrocytes One has tunica intima Usually very porous (fenestrated), some are not. One cell thick
Function:
Site of oxygen exchange and other nutrients from the bloodstream to other tissues
Venules
Initially only tunica intima Very porous Larger Fairly simple Have thin media and adventitia
Veins
Larger than arteries in diameter, but thinner walls
(because not as much pressure)
Thin walls
All three layers present, kind of merge together
Large lumens
Have valves
Blood brain barrier
Example of a capillaries due to tight junctions
Sinusoidal capillaries
Extremely thin and leaky (liver, marrow)
Menschymal cells
Have long cytoplasmic proteins around capillaries and venules
Have actin, myosin, tropomyosin which suggest mobility
They proliferate following tissue injury to differentiate into new blood vessel endothelial cells
Important to granulation tissue!
Atherosclerosis
Most common form of arteriosclerosis Primarily affects the elastic arteries (aorta, carotid, iliac) & Large muscular arteries (coronary, popliteal) Accounts for more deaths/serious illness in Western world than ANYTHING else.
Arteriosclerosis
The thickening and hardening of the walls of the arteries
Typically occurs in old age
Different types
Atheromas
A necrotic core of lipid, debris, and T-cells
Basic lesions involved
Lipid cores of a surrounding fibrous cap
In small vessels, these are occlusive
Lesions
Lipid cores of a surrounding fibrous cap
Initial lesions are fatty streaks (flat or minimally elevated) and contain accumulation of lipid in tunica intima
Macrophages with large amount of stored lipid (foam cells) accumulate here
Aneurysm
In large vessels
Atheromas weaken the walls & can cause
(aneurysms, ruptures, or predispose to thrombosis)
Can also occur due to genetic syndromes (Marfans) or vasculitis
Infections can occur in rarer causes
Marfan syndrome
Can cause aneurysms
Inherited disorder affects CT
Affects heart, eyes, blood vessels, and bones
Diabetes-related vascular disease
Hyalinization
Tissue degenerates into a translucent, glass-like substance
How does continuous pressure in elastic arteries work?
They always have continuous pressure.
Elastic recoil propels blood after ventricular contraction.
Fenestrated capillaries
Very porous
Inflammation can cause fenestrations to enlarge
Non-fenestrated capillaries
Don’t have pores
Specialized for transport of macromolecules to and from tissues (via pinocytotic vesicles)
These continuous capillaries have tight junctions
Small intercellular clefts present
Ex: muscle tissue, exocrine glands, nervous tissue
Pericytes
Long cytoplasmic proteins
Multi-functional cells that wrap around capillaries and venules
Valves
Also called "venous valves" Inside veins (mostly of limbs) Folds of tunica intima Prevent back flow/overcome gravity in low BP conditions Muscular activities encourage flow
Incompetent Valves
Located in inferior vena cava and coronary sinus
Fibrous cap
A layer of CT that is thicker and less cellular than usual subendotheilial CT
Contains lipid-satiated macrophages and smooth muscle cells
Vasculitis
Inflammation of the blood vessels that causes changes in the vessels walls
Can cause walls to thick and narrow which cuts off vital blood supply
