Connective Tissue 3 Flashcards
Blood Components
Erythrocytes (RBCs and Platelets)
Leukocytes (Monocytes, Lymphocytes, Eosoniphils, Basophils and Neutrophils)
General Facts
.38 degrees
* 5X viscosity water –
dissolved proteins, formed
elements
* PH average 7.4 slightly
alkaline (expand here)
* 4-5L
Formed Elements
- Blood cells and cell fragments suspended in
plasma - RBCs, WBCs and platelets
- Formed elements produced through
hematopoiesis - Hemocytoblast (PSCs)
→ myeloid stem cells
→ Lymphoid stem cells
Transport
Dissolved gases
Nutrients
Hormones
Metabolic waste
Regulation
PH/Ion composition of interstitial
fluid….
-Regulates ion levels
-Eliminates acid build up
Restricts Fluid Loss
- Enzymes that respond to breaks in
vessels - Clotting
Defence against pathogens/toxins
- WBC’s
- Antibodies
- Special proteins
Stable body temperature
- Absorbs heat generated by skeletal
muscles
Plasma Proteins
Proteins in solution
* Similar to interstitial fluid
* 7.6g/100ml in plasma
* X5 less in interstitial fluid
* Three protein classes:
- Albumins (60%); osmotic
pressure; transporter
- Globulins (35%);
antibodies/immuno and
transport globulins
- Fibrinogen – Clotting
- Molecules can interact making
insoluble fibrin strands
→>framework for a blood clot.
- 1% other proteins with
specialised functions
Blood haematocrit - % of whole blood
occupied by red blood cells
- 42% females
- 46% males
- Male sex hormones (androgens) stimulate red blood cell production
- Blood can be separated out by centrifugation
Clinical Relevance of Haematocrit
Anaemia
- Decreased
hematocrit
*Polycythemia
- Increased
hematocrit
(>65%)
RBCs
- 99% formed elements
- Red pigment – haemoglobin – binds O2/CO2
- RBC/ul – 4-6 million!!!
- Biconcave disc
- Large surface area:volume - efficient gas exchange (total 3800 sqm!!!)
- Stack and flow!
- Very flexible
Haemoglobin
- 95% of RBC protein
- Grams of Hb/100ml of whole blood
- 2 alpha and 2 beta polypeptides
- Each Hb chain has a haem (pigment)
- Binds O2 – shade difference
Erythropoiesis
- Erythropoiesis – formation of RBCs
- Red bone marrow
- In extreme situations yellow marrow
converts to red marrow
Blood production
Haematopoiesis
Clinical Relevance of Hb
- Sickle cell anaemia
- Autosomal recessive
- Mutant Hb gene leads
to mutant Hb protein
Hb-S - When Hb-S gives up O2
it forms rodlike structures - ‘Crisis’- pain and
damage due to
blocked capillaries
Leucocytes (WBC)
- Nucleus
- 6-9000/ul
- Larger than RBC
- Role in immune system, removal of foreign substances
& defective cells/debris, inflammation. - Mostly located in connective tissue proper or lymph
organs
Granulocytes (Leukocytes)
- Neutrophils; eosinophils and basophils
- Granules are vesicles and lysosomes
Agranulocytes (Leukocytes)
- Monocytes and lymhocytes
- Non-granular cytoplasm
normal differential count for white
blood cells:
Neutrophils (60-70%)
Lymphocytes (20-40%)
Monocytes (3-10%)
Eosinophils (1-4%)
Basophils (~1%
Granulocytes- Neutrophils
- Most common
(50-70% of WBC) - 10-12μm
diameter - 2-5 lobed nucleus
- Lysosomal and bactericidal
granules - First to injury site
- Cell scavengers
/phagocytes
Granulocytes- Eosinophils
- Eosin +ve granules
- Rare (2-4% of WBC)
- 10-12μM diameter
- Exocytosis of toxic compounds
- Attack antibody coated objects
- Increased in allergic
conditions (e.g. asthma)
and internal parasitic
infections (e.g. worms)
Granulocytes- Basophils
- 0-5-1% (most rare!)
- 8-10μm diameter
- Migrate to injury site
- release histamine
dillates blood vessels
and heparin
prevents blood clotting
Agranulocytes- Monocytes
- 12-20μm diameter
(largest) - 3-8% of WBC
- Kidney shaped nucleus
- Circulate in Blood for 2
days, then mature in
tissues - Mature into macrophages
- Cell-mediated immunity
Agranulocytes- Lymphocytes
- Smallest WBC
- Diameter 8-10μm
- 20-30% of WBC
- Large nucleus
- B-cells – differentiate into plasma
cells (antibody production). - T-cells – CD4 and CD8
- NK (natural killer) – immune
surveillance and destruction of
abnormal tissue (cancer).
Platelets
- Can look spindle shaped in smear
- Fragments shed from cytoplasm of
megakaryocytes (slide17!) - In BM, slowly sheds cytoplasm in
membrane enclosed packages - Around 4000!
- 2-4μm diameter
- Role in blood clotting – make clotting
factors (III,IV, V, VIII and XIII) - Lifespan of 9-12 days
- Removed in spleen by phagocytes
Clinical Significance of Platelets
- Hereditary disorder mostly
affecting males - Inadequette clotting factor
formation (VIII) - Delayed clot
formation - Haemorrhage
Lymphatic SYSTEM
- Lymphatic capillaries and vessels
Lymphocyte producers: - Lymphoid tissue – e.g. tonsils
- Lymphoid organs – spleen and
thymus - Production/distribution of
lymphocytes - Lymphopoiesis
lYMPH
Blood plasma components (not large plasma
proteins) pass through capillary walls into interstitial fluid.
* Concentration gradient prevents flow from interstitial fluid to
blood.
* Passes into permeable lymph capillaries = lymph.
Collecting drainage – lymphatic capillaries
- Capillaries deliver more liquid to tissues than they carry away.
- The residual liquid (15%) is returned via lymphatic system.
- Helps distribute lymphocytes, hormones, nutrients etc…from
interstitial fluid
Lymphatic capillaries
- Branch through peripheral tissues
- Not present in CNS, BM or cornea
- Originate in blind pockets – cul-de-
sac! - Large diameter
- Thin walls – endothelial cells
- Absent/incomplete basement
membrane - Not tightly packed but overlap
- This creates a valve for the one
directional flow of lymph
Lymphatic vessels
- Small lymphatic vessels contain valves
- Ensure flow from trunk to thoracic cavity
- Present in almost every tissue
- Often associate with blood vessels
- Plasma →interstitial fluid → lymph
Lymphoid tissues
- Specialised connective tissue dominated by
lymphocytes. - Example – tonsils.
- These are large nodules in pharynx wall.
- Germinal centres contain dividing lymphocytes
Lymphoid organs
- A fibrous connective tissue
capsule separates these
organs. - Lymph nodes, the thymus
and the spleen.
Lymph nodes
- Kidney bean!
- Small, oval, 1-2mm.
- Collagen fibres extend in –
trabeculae. - Helium – point of attachment
for blood vessels and nerves - Afferent lymphatics – carry in
lymph. - Efferent lymphatics – carry
lymph away
Lymph node function
.filter
* Purify lymph before entry to venous system.
* Remove 99% antigens.
* Macrophages phagocytose
* Antigen presentation to lymphocytes.
* Strategically positioned to avoid infection – groin, digestive and
respiratory tract protection.
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Thymus
- Right and left lobes
- Septa separate out the lobes into lobules.
- Contains many lymphocytes.
- Produces hormone Thymosin
Spleen
- Largest collection of tissue.
- Preforms the same function as
lymph nodes…but for blood. - Recycling red blood cells.
- Initiation of immune responses – B
and T cells
45
Spleen histology and function
- 12cm
- Capsule - collagen/elastin
- Trabecula – blood vessels.
- Red pulp – blood+ fixed
macrophages in network of
reticular fibres - Removes abnormal blood
cells. - Immune cell activity
- White pulp – Rich in variety of
immune cells
What aids lymph flow?
1)Smooth muscle contraction
2)Skeletal muscle contraction
3)Inhalation
Clinical Significance of Lymph Fllow
- BLOCKAGE OF
LYMPH VESSELS - Fluid accumulates
in interstitial fluid,
proteins retained - FILARISIS
- Nematodes infect
lymph nodes - Elephantiatis
