BIO Exam 2: Blood and Blood Vessels Flashcards
Blood: Breakdown
About half the volume is non-cellular
Plasma:
Mostly water
Dissolved solutes (glucose, amino acids, hormones, nucleotides, etc.)
Ions (Na+, K+, Cl-, Ca2+, HCO3-)
Buffered to pH 7.4
Various proteins:
Albumin
Antibodies
Clotting Proteins
Blood Cells
By volume, roughly half of blood is cells
Erythrocytes (red blood cells)
Gas transport
Leukocytes and Lymphocytes (white blood cells)
Immunology
Platelets (thrombocytes)
Platelets (thrombocytes)
Made by fragmentation of a megakaryocyte
Abundant. ~250,000 per microliter
Key player in preventing blood loss
Platelet Function
Platelets don’t bind to the inside of an intact blood vessel
If there is damage, platelets bind
Platelets bind to more platelets (a Platelet plug forms quickly but isn’t tough)
Blood Clotting
Platelet plug is reinforced by a blood clot
Using proteins in plasma
Activated platelets activate plasma proteases
Most require Ca2+ as a cofactor
Fibrinogen –>Fibrin
Fibrin can polymerize, forming a net
Blood Vessels: Path
Two Circuits:
Heart–>Arteries
–>Arterioles–> Capillaries–>
–>Veins–>Venules
Blood Vessels: Function
Arteries and veins are wide, capillaries are tiny
All contain endothelial cells, little else in capillaries
Arteries and Veins have muscle layers (much thicker in arteries) and an extracellular matrix: in arteries, more Elastin for stretching
in veins more Collagen for strength
Flow Rate: Two ways to think about the rate of blood flow.
Volumetric – how many mL pass one point in one second?
Linear – how many mm does the blood move in one second?
Both types of flow rate are controlled by
1) pressure and 2) vessel diameter
Pressure is highest close to the hear
Flow Rate: Vasoconstriction and Vasodilation
Vasoconstriction: decreases volumetric flow rate and increases linear flow rate
Vasodilation: increases volumetric flow rate decreases linear flow rate
Linear flow rate is very slow
The total area is huge with many capillaries
Capillaries
Capillaries are optimized for exchange
Slow linear flow rate – lots of time for exchange to happen
Thin endothelial cells and little extracellular material
Very poor tight junctions – lots of leakage between cells
Pores between cells:
Water and small molecules can pass
Proteins are too big to move
Direct connection of plasma to extracellular fluid (ECF)
Capillaries (2)
Filtration through the pores and between cells. Due to pressures involved
Blood pressure is higher at atrial side
Water and solutes leave (glucose, amino acids, etc.) Proteins don’t.
The key protein is Albumin.
Lymph (90%/10%)
Osmotic pressure brings 90% of the water back to the plasma at the venule side
10% Into lymph vessels
Blood Movement in Veins
Low pressure and low flow rate in veins
Valves to allow for one-way movement
Skeletal muscle can help move blood through veins
