Blood and Circulatory System Flashcards
blood function overview
- circulates to maintain relative constant environment for all cells
1. carries nutrients and oxygen to tissues 2. carries carbon dioxide from tissues to lungs 3. carries waste products from tissues to kidneys for excretion 4. carries hormones 5. temperature control by transporting heat from deeper structures to surface of body 6. water balance 7. buffers like bicarbonate maintain constant pH 8. clotting prevents excess blood loss from injury 9. contains factors for defense against disease
formed elements of blood
rbc, wbc, blood platelets
rbc and platelets lack nuclei
Red blood cells/erythrocytes
biconcave discs, the shape allows for large surface area for oxygen exchange
presence of hemoglobin within the RBC allows transport of oxygen and red colour
Hemoglobin
organic compound made of 4 red porphyrin pigments called memes, each containing an atom of iron and globin, which consists of 4 amino acid chains (hemoglobin=Hb)
iron metabolism
iron is lost through feces, urine, and sweat, as well as during fetus development, nursing, and menstruation
methemoglobin
true oxidation product of Hb that is unable to transport oxygen because the iron is in the ferric state, not ferrous
methemogloniemia
nitrites and chlorates with methemoglobin cause nitrate poisoning from fertilizer and chlorate poisoning from weed killers in cattle
carboxyhemoglobin
stable compound formed when carbon monoxide, present in exhaust fumes, combines with Hb
-affinity for Hb for CO is 210 times greater than its affinity for O2
Carboxyhemoglobin is unable to carry oxygen and the individual dies of suffocation
cyanide poisoning
produces suffication by interfering with the utilization of oxygen by tissues
- has NO effect on oxygen carrying ability of blood
- may occur when cattle each stunted or frosted grain sorfhums
methylene blue
used to treat cyanide poisoning by forming methemoglobin in blood, reacting with cyanide to form cyanmethemoglobin, an inactive compound that is slowly degraded and detoxified by body
RBC formation
in adults it occurs in bone marrow, also producing granular leukocytes
in fetus the liver, spleen, and lymph nodes produce RBC
destruction of RBC occurs after 3 to 4 months in circulation
RBC disintegrates, releasing Hb into blood and broken cell debris is removed from circulation by macrophages
Fate of Hemoglobin
Hemoglobin is converted bilirubin and then further to urobulin, which gives urine it’s yellow colour
Jaundice or Icterus
when bilirubin accumulates in blood it results in a condition in liver and intestines, causing a mucous membrane that makes mouth and eyes appear yellow
caused by liver damage, occlusion of bile ducts, or by destructive blood diseases
Hemolysis
breakdown of RBC so Hb escapes into the plasma
caused by bacterial toxins, snake vemons, blood parasites, hypotonic solutions, and many chemicals
-the resulting Hb in plasma gives it a reddish colour, a condition known as hemoglobinemia
Hb excreted in urine is known as hemoglobinurea
hemaglutination
clumping of RBC, usually when cells of one species are transffered to another, or when given the wrong blood type to humans or horses
Normal values of blood pressure
systolic: 90-120, dystolic: 60-80
Anemia
results if either the number of functional RBC or the quantity of Hb is decreased far below normal levels; leads to heart failure
- may be caused by deficient blood formation from poor nutrition and deficiency of iron, copper, and vitamins
- loss of blood due to hemorrhage from wounds or because of parasites such as stomach worms or lice
- deficient secretion of intrinsic factor from stomach necessary for vitamin B absorption
- hemolysis or immature RBC
Platelets/thrombocytes
fragments of megakaryocytes: larges cells formed in bone marrow
surrounded by plasma membrane and contain microtubules, lysosomes, mitochondria, and golgi vesicles, but not nuclei
important for blood clotting and reducing blood loss
platelet/thrombocytes process
adhering to vessel walls and each other at site of injury, they form a plug that occlludes the opening
also release serotonin that cause local constriction of injured vessels
Leukocytes/WBC
nucleated and capable of independent movement
subtypes: Granulocytes and Agranulocytes
-gran. last hours, monocytes months, and lymphocytes years
non-functional in blood stream and are transported to tissues when needed
granulocytes
contain granules within cytoplasm that stain with wrights stain
subtypes: neutrophils, eosinophils, basophils; formed in red bone marrow
eosinophils (acidophils)
stained red with acid dye eosin
increase in number during CHRONIC infection
amoeboid and phagocytic
function: detoxify foreign proteins introduced via lungs, GI tract, or toxins made by bacteria and parasites
-number increase in allergic reactions
basophils
stained with methylene blue, contains heparin preventing clotting
contain histamine, badykinin and serotonin
-are also the mast cells present in conn. tissue
neutrophils
- stained diff, neither red nor blue
- first defense against infection by migrating to bacteria, pass through blood wall and engulf and destroy bacteria
- while destroying bacteria, neutrophils also degrade dead tissue in area, resulting in PUS
- localized accumulation of pus is called an ABSCESS
- increase of neutrophils present during infection
tissue injury, neutrophils, and phagocytosis
autolysis of gran. leads to lysosomal enzymes that act on surrounding tissue, releasing chems that attract neutrophils
injured tissue=release histamine=inflammation
histamine increases blood flow, causes redness and inflammation
dilation of capillaries: more proteins and fluid leak out, more fibrinogen leaks out, coagulation quicker and barrier against spread of infection quicker
Neutrophilia
inflamed tissue release leukopoietic factor, acts on marrow, releasing more neutrophils and increases rate of granulocyte formation
increased number of neutrophils is neutrophilia, and occurs during bac. infection, cancer, metabolic poisoning, hemorrhage, and exercise
Agranulocytes
few granules,
subtypes include monocytes and lymphocytes
monocytes
largest WBC
- phagocytic and used for less acute infections, ie. tuberculosis
- when monocytes from from blood enter tissues, they develop into large phagocytes called MACROPHAGES
lymphocytes
variable in size and appearance; large nucleus surrounded by small cytoplasm
function: to respond to antigens (foreign substances) by forming ANTIBODIES that circulate blood or in development of cellular immunity