Transcript The Lymphatic System and the Blood

2010-2011
Overview
Fluid of life—why?
 Blood vessels form from mesoderm
 Blood produced 2 wks after vessels are
formed, during the 5th week of life

What is blood?


Connective tissue
Different from others
 Matrix not a solid or semi-
solid material
 Matrix of blood is plasma
○ watery substance
○ Yellowish
○ 90% Water
○ 7% protein
○ 1% minerals
○ 2% other materials incl.
atmospheric gases, chem
signals, and nutrients
More on plasma


Atmospheric gases
incl. oxygen, carbon
dioxide, and
nitrogen
Comprises 55% of
blood volume
Formed elements

Remaining 45% of
blood volume:
 Erythrocytes (RBCs)
 White blood cells
(WBCs)
 Thrombocytes
(platelets)
Hematocrit

Calculates the
volume of red blood
cells making up the
blood
Can you answer these questions?
What is the blood composed of?
 Why is the blood unlike any other
connective tissue?
 What does a hematocrit tell you?

Tests that monitor health of RBCs
CBC: full blood count or hemogram
 Determines the amount of cytoplasm in
the RBCs, the mass of Hemoglobin
molecules, and the concentration of
Hemoglobin.
 Helps to diagnose certain RBC
disorders

Red Blood Cells

No mature nucleus
 No DNA soooo….
○ Use enzymes to carry out their tasks =
reticulocytes
○ Live max 120 days
○ No way to repair & replace damaged cellular
components
○ Appear red b/c of hemoglobin
 Contains ironfacilitates the transport of O2 and CO2
 4.8 million RBC / mm3 in women
 5.4 million RBC/mm3 in men
Blood Type

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
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

Genetic
Determined by the proteins on the surface
of the RBC membrane
ABO blood group system
AB universal acceptor
O universal donor-has no proteins on the
membrane
Blood will attack non-self so it’s important
to match blood types for transfusions
Rh Factor
The D protein
 Most are positive
 If a woman is negative and conceives
with a positive man, problems can
arise—erythroblastosis fetalis

This can lead to anemia, a condition marked by weakness
and fatigue. Severe anemia can lead to heart failure and
death. The breakdown of RBC leads to the buildup of
bilirubin which can lead to jaundice and brain damage.
Prevention of erythroblastosis
fetalis
Give Rh immune globulin to rid mother
of fetal blood cells before she becomes
sensitized
 Given whenever there is a possibility of
fetal blood mixing with maternal blood
following childbirth, abortion,
miscarriage, prenatal testing.
 Once sensitized the woman will always
react against Rh+ cells

Can you answer these questions?
1.
2.
3.
4.
5.
6.
How are RBCs different from most other
cells?
How does the lack of a nucleus affect
RBCs lifespan?
What is hemoglobin and what does it do?
Why are RBCs red?
What is blood type? What do the different
blood types mean?
Why is it dangerous for an Rh- woman to
have an Rh+ baby?
White Blood Cells
WBC : RBC = 1 : 500 or 1000
 Use blood to move from bone marrow to
the tissues
 5 types (differential WBC count
measures them)






Neutrophils (Most abundant)
Lymphocytes
Eosinophils
Monocytes
Basophils (Least abundant)
WBC’s
Agranulocytes
AKA : Mononuclear
Lack visible granules in
cytoplasm

Granulocytes
Noticeable granules that
produce specialized
secretions for fighting
infection
Nucleus is polymorphic,
lobed, unusually shaped
Monocytes
Lymphocytes
T & B cells
Eosinophils, basophils,
neutrophils
Neutrophils
Granulocyte
 Most common WBC
 Nucleus = 2-5 lobes
 Found in the blood
 First responders in the inflammation
response due to environmental
exposure, some cancers, bacterial
infection
 Predominant cell in pus

Eosinophils




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

Granulocyte
5% of WBCs
Bi-lobed nucleus
Combats parasitic infections (protista,
worms)
Secretions produced related to allergies
Normally in thymus GI, ovaries, testes,
spleen, uterus, lymph nodes
NOT in lungs, esophagus or skin disease
Basophils



Granulocyte (least common)
Susceptible to basic dyes
Large, bi-lobed nucleus (similar to mast
cells)
 Granules obscure the nucleus
 “Bas-ically all granules”
Involved in allergies.
Stores, secrete histamine & heparin
(anticoagulant)
 Found where allergic reactions are taking
place


Agranulocytes
Lymphocytes
 Immune cells

 NK cells (no prior activation needed)
 T lymphocytes (mature in thymus)
○ Helper: direct immune response
○ Cytotoxic: release cytotoxin to kill pathogen
infected cells
 B lymphocytes (mature in bone marrow):
Use antibodies to neutralize pathogens
Monocytes
Agranulocyte
 Largest of WBCs

- shaped nucleus

 Mono = kissing = Love = heart
Many vesicles in cytoplasm for
processing pathogens
 Perform phagocytosis - uptake &
digestion of pathogens

 Fragments signal T-lymphocytes to the area
Platelets
Cell fragments derived
from larger cells called
megakaryocytes.
 Have sticky proteins

 Reduce blood flow to an affected area.
 Reduce blood loss

Sensitive to many types of hazardous
chemicals and pollutants
Can you answer these questions?
Describe the characteristics & functions
of all granulocytes, agranulocytes, and
platelets.
 Compare and contrast the structure &
function of RBCs and WBCs
 Why are Platelets called the “Band-Aids”
of the blood?

Red Blood Cell Function
Carry oxygen from the lungs to the body
 Carry carbon dioxide from the body to
the lungs

Alveoli-where gas
exchange happens in
the lungs
 RBC in the capillaries that surround the
alveoli oxygen enters

 Only if the partial pressure of oxygen outside
is higher than inside

In cytoplasm of RBC oxygen binds to
Hemoglobin
Hemoglobin



Four oxygen molecules
bind to hemoglobin (w/ the
iron)
Carries CO2 also; binds to
a different area of the
molecule than O2
Percent saturation: the
amount of oxygen that is
dissolved in a solution of
hemoglobin molecules
 O2 sats = 98% or above

Difference with myoglobin
in muscle
 Fills w/ oxygen faster
 Hemoglobin collects oxygen
a low partial pressures

In the tissues the oxygen is released and
carbon dioxide enters the RBC, binds to
Hemoglobin.
 Partial pressures of the gases must appropriate
 Some cellular wastes stimulate the release of the
oxygen from the hemoglobin
○ Allows RBC to give more O2 to tissues w/ high
metabolic needs
Carbon Dioxide

Carried 3 ways in the blood
1. Carried in the blood as a gas (10%)
2. 22% is in the plasma, binds to empty hemoglobin
in tissues away from alveoli & never enters a RBC
3. As a bicarbonate ion
○ Carbon dioxide is dissolved in water forming
bicarbonate ion
○ Dissolves in the blood plasma and cytoplasm of
RBCs
 Carbonic anhydrase: enzyme in RBC that stim’s the
formation of bicarbonate ions
Movement of gases
High concentration  low concentration
 For Oxygen:

 Partial pressure is higher in blood than in
tissues

For Carbon Dioxide:
 Partial pressure is higher in tissues than in
blood
Carbon dioxide intoxication
Occurs when the CO2 is extremely high
in the environment or the blood
 Acute: high levels in the air
 Subacute: toxicity caused by the body’s
failure to eliminate carbon dioxide

 Decreases blood’s pH (what kind of acid
does CO2 form when it dissolves in water?)
○ Carbonic acid!
Can you answer these questions?
What is the purpose of RBCs?
 Where does oxygen bind to the Hb
molecule?
 Where does Hb collect oxygen? Then
what happens?
 Describe the partial pressures that must
be present for oxygen to diffuse from
RBC to tissues and for carbon dioxide to
move to the cells?

White Blood Cell Function

In general:
 Fight infections & disease
 Granulocytes: granules of toxic chemicals
that kill microorganisms & regulate reactions
to foreign materials in the body
Neutrophil function
Pass through capillaries to
tissues to with infections.
 Attracted to affected areas by factors
secreted by damaged cells/tissues
 Stick to injured tissues, use phagocytosis to
engulf remains of bacteria and damaged cells
 Secretes antibiotics-harms/kills bacteria
 Secretes other chemicals that stim.

 Inflammation ↑ blood flow to the area & ↑ WBC
concentration
Eosinophil function
Secretions defend against
parasitic infections esp. protists
& worms
 ↑ in eosinophils = parasitic infection
 Granules contain major basic protein to kill the
parasites
 Secrete chemicals associated w/ allergies

Basophil function
Secrete histaminestim the
immune response
 Overproduction of histamine  runny nose,
sneezing, watery eyes
 Mast cells-special kind of basophil

 Inflammation of tissues
 Secrete chemical that attract neutrophils
 Found in walls of small bl. vessels
Monocyte function
Clear granules give cytoplasm
a grey appearance
 When they leave the bone marrow they
become either:

 Circulating monocytes
○ Detect infections in blood
○ Bone growth & maintenance
 Tissue monocytes (macrophages)
○ Remove dead cells
○ Attack microorganisms that are difficult to kill (fungi)
Lymphocyte function
Stay tuned! We’ll
talk about it later….for now,
they carry out most of the
duties of the immune system

Can you answer these questions?
Which WBC is in charge of engulfing
bacteria?
 Which WBC is in charge of protecting us
from parasites?
 Which WBC differentiates into cells that assist
in bone growth and maintenance or are
macrophages that protect against fungal
infections?
 Which WBC secretes major basic protein?

Platelets’ function

Blood clotting
 Platelets adhere to injured area
 Activation of blood clot formation

Important that clot forms by injury only
 Intact cells secrete prostacyclinprevents platelet
activation
Clotting Cascade
1.) BV damaged, releases “distress chemicals”
2.) Clotting factors stim. other factors that communicates presence
of damaged tissues
a.) platelets stick to damaged tissues & each other
b.) Platelets secrete prothrombin activator & Ca2+
- Catalyze conversion of prothrombin to thrombin
c.) Thrombin causes fibrinogen  fibrin
d.) Fibrin forms a sticky mesh that adheres to thrombocytes
and other blood components (clot)
- Clot forms a barrier that prevents blood loss & impedes
the passage of microorganisms into tissues
- Calcium ions = catalyze PT to T
- Vitamin K = synthesis of clotting factors
Clotting Cascade again!
START:
Damage to
tissue
Platelets
adhere to
exposed
collagen
END: Fibrin
forms clot,
traps more
platelets
Platelets
adhere to
damaged
tissue & each
other
Ca2+
Thrombin
converts
fibrinogen to
fibrin
Platelets &
damaged
tissue secrete
prothrombin
activator
Prothrombin
thrombin
Why is the cascade so complicated?
So the blood doesn’t clot unintentionally!
 They aren’t permanent
 Plasminogenplasmin (digests fibrin and
dissolves a clot)
 Healthy cells near the clot secrete TPA
(tissue plasminogen activator)dissolves
fibrin as well.

Can you answer these questions?
1.) What is the purpose of prostacyclin?
2.) What is the purpose of a clot?
3.) What are the steps of the clotting
cascade?
4.) What is the role of calcium and vitamin K
in clot formation?
5.) Why is the clot cascade so complex?
6.) What do plasmin and tissue plasminogen
have in common? What’s the difference?
In General…
Adults: bone marrow
 Embryo: Liver

 Different forms of Hb throughout development
allow fetus to adapt to varying metabolic needs
for oxygen
11 million/sec in an adult
 1 WBC produced for every 700 RBCs

In General…
Adults: bone marrow
 Embryo: Liver
 11 million/sec in an adult
 1 WBC produced for every 700 RBCs

GF
Myeloid
stem cell
(progenitor)
Hematopoietic stem cell
Or
Multipotent stem cell
Or
Pluripotent stem cell
GF
Lymphoid
stem cell
(progenitor)
The life history of erythrocytes
(RBCs)

Blood oxygen decreases
 Stimulates erythropoietin production from
kidneys and liver
ErythropoietinErythropoiesis in red
bone marrow (where is this found?)
 Immature erythrocytes have a large
nucleus
 Hb production begins in basophilic
erythroblasts
 Reticulocytes: lose nucleus, after 1-2
days in circulation lose organelles

If the need for oxygen is great,
erythropoiesis will occur at an increased
rate.
 This means an increased amount of
polychromatic erythroblasts will enter
the blood stream
 Erythropoiesis of a single erythrocyte
takes approximately 4 days


Normal bone marrow has an abundance
of newly formed RBCs and
megakaryocytes (which produce
platelets)
Old erythrocytes get gobbled up!
Removed by macrophages
 Globin (protein) is broken into individual
amino acids & recycled
 Iron is recycled
 Parts of the molecule are converted to
bilirubin

 Processed in liver, secreted in bile in small
intestine
○ Bacteria convert into pigments feces color
○ Some excreted in urine yellow color
A bit about WBCs:
Lifetime = 13-20 days
 Then destroyed in lymphatic system
 When released from bone marrow called
stabs or bands

 Esp. neutrophils b/c their nuclei aren’t lobed,
yet, and look like a rod (stab = German for
rod) or bands
Functions of Lymphatic System
1.) Maintain fluid balance in the tissues
○ 30L fluid from capillaries to interstitial and only
27L pass from interstitial back into capillaries
qd (every day)
○ If fluid left in the body  tissue damage
○ 3L fluid enter lymph capillaries, called lymph
 Then to lymph vessels & return to blood
2.) Absorb fats & other substances from
digestive tract (chyle)
3.) Defense
○ Nodes filter lymph & spleen filters blood of
microorganisms & foreign substances
Lymphatic System Structures

Lymph
 Like plasma: ions, nutrients,
wastes from interstitial spaces
 Hormones, enzymes from cells in
tissues


Lymphocytes
Lymph vessels
○ Flow of lymph produced by gravity
or skeletal muscle, passively drains
to lower body from upper
○ Valves-no backflow
○ Lymphatic trunks drain lymph from
larger areas of body
 Clusters of lymphatic tissue
Lymphatic System Structures

Lymph nodes
 Collections of lymphatic
tissue covered by
connective-tissue
capsules
 Eliminate antigens from
lymph as lymph flows
thru the node.
 In groups along the
larger lymphatic vessels
Lymph node structure

2 divisions: Cortex (outer) & Medulla (inner)
 Cortex
○ Has “compartments” called lymphatic nodules
○ 2 layers: inner layer called germinal center where Blymphocytes are found. In the “wall” surrounding the
germinal center is where T-lymphocytes are found.
○ Nodules are sep’d by trabeculae—extensions of the
capsule—fibrous covering of the node
○ Cortical sinus: spaces where lymph flows through
 Medulla
○ Medullary sinus = space where lymph flows throught he
center of the node, contains macrophages
○ Medullary cord = contains lymphocytes
Lymphatic System Structures

Tonsils
 Swollen cluster of lymphatic tissue in throat
 Form protective ring of lymphatic tissue around the openings
between the nasal and oral cavities & pharynx
 Provide protection against bac and other harmful material
 Eventually disappear in adults

Spleen
 Detects and responds to foreign substances in the blood
 Destroys worn out red blood cells
 Acts as a blood reservoir
 Structure
○ Left side of the extreme superior, posterior corner of ab cavity
○ White pulp: Contains T & B lymphocytes
 Assist body with infections that require a large immune response
○ Red pulp: removes old/damaged RBCs
Lymphatic System Structure

Thymus
 Deep to manubrium
 In newborn, extends length of thorax & grows until
puberty, then decreases in size
 Function
○ Produce lymphocytes that move to other lymph
tissues, but most degenerate before moving on
○ Produces secretions that mature T-lymphocytes
 Can’t destroy normal body cells (Self-tolerance)
Immunity words to know:

Antigen: a substance that can
induce an immune response.
Hapten: A molecule that can cause an
immune response when attached to
blood proteins.
 Two ways the immune system can
respond to disease:

 Innate immunity
 Acquired immunity
Lines of defense

1st line: Non-specific barriers
 broad, external defense
○ “walls & moats”
 skin & mucous membranes

2nd line: Non-specific patrols
 broad, internal defense
○ “patrolling soldiers”
 leukocytes = phagocytic WBC

3rd line: True immune system
 specific, acquired immunity
○ “elite trained units”
 lymphocytes & antibodies
○ B cells & T cells
Bacteria & insects
inherit resistance.
Vertebrates
acquire immunity.
1st line: Non-specific External defense

Barrier
○ skin

Lining of trachea:
ciliated cells & mucus
secreting cells
Traps
○ mucous membranes, cilia,
hair, earwax

Elimination
○ coughing, sneezing, urination, diarrhea

Unfavorable pH
○ stomach acid, sweat, saliva, urine

Lysozyme enzyme
○ digests bacterial cell walls
○ tears, sweat
2nd line: Non-specific patrolling cells

Patrolling cells & proteins
bacteria
 attack pathogens, but don’t
“remember” for next time
○ leukocytes
 phagocytic white blood cells
 macrophages, neutrophils, natural
killer cells
macrophage
○ complement system
 proteins that destroy cells
○ inflammatory response
 increase in body temp.
 increase capillary permeability
 attract macrophages
yeast
Leukocytes: Phagocytic WBCs

Attracted by chemical signals released by
damaged cells
 ingest pathogens
 digest in lysosomes



Neutrophils
 most abundant WBC (~70%)
 ~ 3 day lifespan
Macrophages
 “big eater”, long-lived
Natural Killer Cells
 destroy virus-infected cells
& cancer cells
Destroying cells gone bad!

Natural Killer Cells perforate
cells
 release perforin protein
 insert into membrane of target cell
 forms pore allowing fluid to
flow in & out of cell
 cell ruptures (lysis)
natural killer cell
vesicle
○ apoptosis
perforin
cell
membrane
cell
membrane
perforin
punctures
cell membrane
virus-infected cell
3rd line of defense: Acquired
Immunity

Body adapts to specific infections
 Body learns the nature of the enemy (invading
microorganisms)
 Can launch a specific attack against the enemy
 More successful than innate
 Able to prevent future infections from the same
microorganism

Two divisions: Primary Response and
Secondary Response
How are invaders recognized: antigens

Antigens
 proteins that serve as cellular name tags
○ foreign antigens cause response from WBCs
 viruses, bacteria, protozoa, parasitic worms, fungi, toxins
 non-pathogens: pollen & transplanted tissue

B cells & T cells respond to different antigens
 B cells recognize intact antigens
○ pathogens in blood & lymph
 T cells recognize antigen fragments
○ pathogens which have already infected cells
“self”
“foreign”
B cells

Humoral response = “in fluid”
 defense against attackers circulating
freely in blood & lymph

Specific response
 produce specific antibodies
against specific antigen

Types of B cells
○ plasma cells
 immediate production of antibodies
 rapid response, short term release
○ memory cells
 long term immunity
T cells

Cell-mediated response
 immune response to infected cells
○ viruses, bacteria & parasites (pathogens) within
cells
 defense against “non-self” cells
○ cancer & transplant cells

Types of T cells
 helper T cells
○ alerts immune system
 killer (cytotoxic) T cells
○ attack infected body cells
Immunoglobins





IgG: most common, fight general infections,
pass from mom to child in pregnancy
IgA: in mucous membranes aof the digestive
system, milk, tears, saliva
IgM: natural defenses against general bacterial
infections
IgE: stim basophils and mast cells to defend
against parasites fungi and worms
IgD: on membranes of B-lymphocytes.,
maturation of B-lymphocytes into plasma and
memory cells
Secondary Immune Response
Body responds more quickly
 Memory cells “remember” past encounters
with antigens and immediately px antibodies

 Eliminates macrophage activity
Memory cells don’t last forever—they die and
take their memory with them
 After 5 yrs of not being exposed to a particular
antigen, the body loses much of the
secondary immune response

Inflammation
Outcome of acquired immune response
 Increases bl circulation to affected area

Bv’s dialate to increase blood flow
Immune cells go to injured area
Immune resp. takes place at the site it’s needed
Tissues = red and warm b/c of the blood that
enters the area, ↑ in temp anti-microbial
 Pain from pressure of swollen tissues on nerve
endings
 Normal functions return when the tissue is fully
recovered




Immunization



Medical strategy for building up the body’s acquired
immune response
Natural: exposed to foreign antigens as a part of
everyday life.
Artificial: therapeutic exposure to antigens
 Active: stimulates the primary response by introducing
foreign antigens into the body: Vaccines.
 Passive: occurs naturally during embryological development
when antibodies from the mother’s blood stream are passed
to the fetus
○ Contain certain antigens from the microorganism (parts of the
microorganism)
 Breast feeding
 Inject large amts of general antibodies to fight disease
- Globulin injections remove certain microorganisms from the body.