Download Blood: Chapter 16 - Madeira City Schools

•Blood: Chapter 16
•Functions
Transporting substances between body
cells and external environment
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Oxygen
Nutrients
Carbon dioxide and other wastes
•Functions (cont.)
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2. Maintaining homeostasis
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Body temperature
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pH (blood is a buffer)
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Defense mechanisms -- cleansing
and clotting of wound, fighting
disease
•Blood composition
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Red blood cells
White blood cells
Platelets
Plasma -- contains:
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water, amino acids/proteins,
carbohydrates, lipids, hormones,
electrolytes, cell wastes, vitamins
•Blood volume
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Determined by:
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Body size (reason for weight limit for donors)
Fat tissue in body
Body’s level of electrolytes and fluids
•Interstitial fluid
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Extracellular fluid (fluid outside the cells)
that bathes cells of tissues
Flows back and forth between blood and
cells, carrying nutrients and wastes
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Lymph
system
•Lymph system
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Lymph made up of interstitial fluid
System fights infection and conveys
immunity
Connected with circulatory system
Made up of lymph nodes, lymph vessels,
organs such as spleen
•Red blood cells
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Also called erythrocytes or RBCs
Biconcave disks (thin near center)
Flexible and rounded
No nucleus
6 micrometers in diameter (1
micrometer = 1/50th width of human
hair)
•RBCs -- form follows function
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Diconcave disks (thin near center) -- more
surface area for gas exchange
Flexible and rounded -- move through small
capillaries better
No nucleus -- more room for hemoglobin
6 micrometers -- just wide enough to go
through capillaries single file
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Hemoglobin
Protein which binds oxygen where oxygen
concentration is high (lungs)
Releases oxygen where concentration is
low
Color is bright red when it has bound
oxygen
•Sickle Cell Anemia
•Sickle Cell Anemia
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Recessive trait
Single mutation produces hemoglobin that
forms long chains in low oxygen
concentration
Makes cells sickle shaped
•Sickle Cell Anemia (cont.)
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Cells no longer rounded so get stuck in
capillaries
Block blood flow -- very painful
No cure yet
Life expectancy in 40s or 50s
•Carbon dioxide
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Carried in blood by reacting with water to
form bicarbonate (HCO3-)
(just like sodium bicarbonate -- baking
soda)
•Red blood cell count
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Smear blood on slide which has grid
Use grid to estimate number of rbc’s in one
cubic mm
Counts reflect blood’s oxygen carrying
capacity
Good diagnostic tool
•Red blood cell count
•RBC life cycle
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Produced in red bone marrow
Average life span -- 120 days
Production rate of red blood cells controlled by
negative feedback mechanism; low oxygen
concentration in blood stimulates production -altitude effect on athletes
red blood cells produced to replace those
destroyed; total number of blood cells in body
remain constant
•Nutrients needed for RBC
production
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Folic acid -- for DNA
Vitamin B12 -- for DNA
Iron -- for hemoglobin
•RBC destruction
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Destroyed by macrophages (large white
blood cells) in the liver and spleen
Destroyed when no longer can carry out
function -- damaged, changed shape so
don’t slip through capillaries as well
•Recycling of iron
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Iron is removed from hemoglobin for reuse
Byproduct is bilirubin which liver excretes
into bile (remember the digestive system?)
•Anemia
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Blood’s carrying capacity below normal
Either because there are too few RBCs
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or because there is too little healthy hemoglobin
in each RBC
•Symptoms and causes
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Fatigue
Shortness of breath
Difficulty concentrating
Many possible causes
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Nutrient deficiency (esp. iron)
Blood loss/RBC destruction (sickle cell)
Low RBC production or RBCs abnormal
•Physiological jaundice
•Physiological jaundice
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Bilirubin accumulates in infant because liver not
active enough to excrete it as fast as it’s produced
Very common, especially in premature infants
Causes yellowing of skin
Treat with light therapy (esp. UV light) which
breaks down bilirubin
can cause brain damage if left untreated too long
•Blood types
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A, B, AB, and O
Rh factor -- either positive or negative
Caused by carbohydrate antigens on
surface of red blood cells (remember
glycoproteins in the cell membrane?)
Recognized as foreign by body if the
antigens don’t match the body’s blood type
•Inheritance of blood types
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3 possible blood type alleles on
chromosome 9
A and B are co-dominant
O is recessive
Rh+ is dominant
•Rh factor in pregnancy
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Rh negative mother carrying Rh positive
fetus may make anti-Rh antibodies
Antibodies could attack fetus
More likely in subsequent pregnancies with
Rh positive fetus
White blood cells
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Aka leukocytes
Different types for different functions
Produced in red bone marrow and lymph
system
Life span depends on type, ranges from 12
hours to weeks, months, even years
T-cells or T leukocytes
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White blood cell taken over by AIDS virus
Important component of leukocyte mixture
White blood cell counts
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Useful in diagnosis, numbers usually
increase when have infectious disease
DIFF = differential WBC
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Gives percentages of each kind of white blood
cell
Helps with diagnosis because different diseases
produce different percentages
AIDS shows reduced number of T-cells
White blood cell functions
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Control disease by phagocytizing
microorganisms
Also control microorganisms by producing
antibodies
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Important role in this function played by
lymphocytes
Also assist in clotting by releasing
histamines which increase blood flow
Pus
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Made up of white blood cells,
dead tissue, dead invaders
Leukemia
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Cancer in bone marrow
Affected marrow produces abnormal WBCs
which don’t mature
Abnormal cells crowd out normal WBCs so
immunity is decreased
Leukemia (cont.)
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Affected marrow produces fewer
RBCs and platelets -- can lead to
anemia and bleeding
Survival rates have improved greatly
over last 40 years thanks to
research; vary depending upon age
of onset
http://www.leukemia-lymphoma.org/all_page?item_id=9346
Platelets
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Thrombocytes
Produced in red bone marrow (precursor
cell shatters into many small platelets)
No nucleus
Lifespan: about 10 days
Clotting
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Platelets are sticky so join together in first
clot
Then help form fibrin that will make a scab
Terrific adaptation
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Clotting process triggered by collagen, air
exposure, and substances released by
injured tissue
Platelets won’t normally contact air, or
injured tissue or collagen (since there’s no
collagen in vessel walls) UNLESS it’s time
to form a clot
Edema
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Tissue swelling
Water leaves plasma and goes to interstitial
fluid
Many causes including kidney/liver
problems (electrolyte imbalance), heart
failure, standing too much in hot weather,
pregnancy -- can be warning sign of
disease