Clinical Medicine Exam 4 Flashcards
What does oxygen saturation measure?
the % of hemoglobin that is saturated with oxygen
What are the components of blood?
- plasma-proteins, water, other solutes
- buffy coat
- formed elements-platelets, leukocytes (neutrophils, lymphocytes, monocytes, eosinophils, basophils), erythrocytes
What are the functions of erythrocytes?
- transport hemoglobin-O2 carrier
- transport CO2 in form of bicarbonate away from the tissues to the lungs
- act as an acid base buffer (binds H+)
If you live at a higher altitude, will you have more or less RBCs?
More
What is blood hematocrit and what is its normal value?
% of blood that is RBCs, 40-45% (females 37-47%, males 42-52%)
What are the exercise precautions for hematocrit levels?
Light exercise: >25%
Resistive exercise: >30%
What are the normal values for hemoglobin?
Women: 12-16 g/dL
Men: 14-18 g/dL
What are the exercise precautions for hemoglobin?
Below 10 g/dL=decreased endurance, may be theshold for resistive exercise/ambulation
What is the definition of orthostatic hypotension?
Drop of 20 mmHg systolic with a subsequent increase in pulse
How many hemoglobin molecules are there per erythrocyte?
How much oxygen is each gram of hemoglobin able to bind with?
- Millions
2. 1.34 mL of O2
Where are RBCs produced?
exclusively in bone marrow
Which bones produce RBCs?
Until 5 years old=virtually all bones
After 20 years old=mostly flat, membranous bones (vertebrae, sternum, ribs, ilea), only proximal portions of humerus and tibia=but overall have a decrease in RBC production
What is the original precursor of RBCs?
hemopoietic stem cells (live in the bone marrow)
What stimulates the production of RBCs?
erythropoietin
Why do you need an adequate number of RBCs? What happens if there are too many?
Adequate=provide sufficient oxygen transport from the lungs to the tissues
Too much=would thicken the blood and impede blood flow
What is the result of decreased O2 transport to tissues?
Increased rate of RBC production
What can cause a decrease in O2 transport to tissues?
Hemorrhage, destruction of major portions of bone marrow, high altitudes, disease of circulation that decreases blood flow through peripheral vessels or a failure of blood oxygen absorption in the lungs
Where is erythropoietin formed?
90% in the kidneys, 10% in the liver
What hormones can increase the production of EPO?
Norepinephrine, epinephrine, prostaglandins
Why do patients with End Stage Renal disease have decreased RBCs?
They only have 10% of the normal erythropoietin
What purposes do the leukocytes generally fill?
- The immune response- innate (granulocytes and monocytes) and acquired (lymphocytes)
- Inflammation
- Allergic reactions
What are thrombocytes?
platelets
What is a left shift?
An increase in the production/release of immature neutrophils, seen in a severe/acute bacterial infection
What are the functions of neutrophils?
phagocytic, first on the scene in injury/infection, are short-lived and self-destruct after they ingest a pathogen
What cells make up the lymphocytes?
B cells, T cells, NK cells
What are the functions of monocytes?
Convert to macrophages-phagocytic activity
Secretion of cytokines-stimulates the attraction of other phagocytes
What are the functions of the eosinophils?
Release of cytokines, growth factors, other enzymes/factors
Important in parasitic infections and allergic responses
What are the functions of basophils?
Secrete: heparin, histamine, serotonin, kinins, leukotrienes, prostaglandins, platelet activating factor
Potentiates other vasoactive substances and inflammatory mediators
Assists in regulation of blood clotting
What are the normal values for WBCs? What are the critical values?
5000-10,000
Exercise may be contraindicated if less than 5000 and a fever greater than 100 degrees
Less than 1000 neutrophils=neutropenic precautions
What are the normal values for platelets? What are the critical values?
150,000-400,000
No resistive exercise under 50,000; serious danger if less than 20,000
What is the function of plasma?
carries antibodies and nutrients to tissues, removes wastes
What is the function of platelets and coagulation factors (from plasma)?
Control clotting