BIO 202 Lecture Notes - Lecture 5: B Cell, Reticular Connective Tissue, Orthochromasia
Blood
Composition
- Blood
oFluid connective tissue
oPlasma
non-living fluid matrix
oFormed elements
living blood "cells" suspended in plasma
oErythrocytes
red blood cells, or RBCs
oLeukocytes
white blood cells, or WBCs
oPlatelets
Physical Characteristics and Volume
- Sticky, opaque fluid with metallic taste
- Color varies with O2 content
oHigh O2 - scarlet; Low O2 - dark red
- pH 7.35–7.45
- ~8% of body weight
- Average volume
o5–6 L for males; 4–5 L for females
Functions of Blood
- Functions include
oDistributing substances
oRegulating blood levels of substances
oProtection
Distribution Functions
- Delivering O2 and nutrients to body cells
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- Transporting metabolic wastes to lungs and kidneys for elimination
- Transporting hormones from endocrine organs to target organs
Regulation Functions
- Maintaining body temperature by absorbing and distributing heat
- Maintaining normal pH using buffers; alkaline reserve of bicarbonate ions
- Maintaining adequate fluid volume in circulatory system
Protection Functions
- Preventing blood loss
oPlasma proteins and platelets initiate clot formation
- Preventing infection
oAntibodies
oComplement proteins
oWBCs
Blood Plasma
- 90% water
- Over 100 dissolved solutes
oNutrients, gases, hormones, wastes, proteins, inorganic ions
oPlasma proteins most abundant solutes
Remain in blood; not taken up by cells
Proteins produced mostly by liver
60% albumin; 36% globulins; 4% fibrinogen
Albumin
- 60% of plasma protein
- Functions
oSubstance carrier
oBlood buffer
oMajor contributor of plasma osmotic pressure
Formed Elements
- Only WBCs are complete cells
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- RBCs have no nuclei or other organelles
- Platelets are cell fragments
- Most formed elements survive in bloodstream only few days
- Most blood cells originate in bone marrow and do not divide
Erythrocytes
- Biconcave discs, anucleate, essentially no organelles
- Diameters larger than some capillaries
- Filled with hemoglobin (Hb) for gas transport
- Contain plasma membrane protein spectrin and other proteins
oSpectrin provides flexibility to change shape
- Major factor contributing to blood viscosity
- Structural characteristics contribute to gas transport
oBiconcave shape—huge surface area relative to volume
o>97% hemoglobin (not counting water)
oNo mitochondria; ATP production anaerobic; do not consume O2 they transport
- Superb example of complementarity of structure and function
- Function
oRBCs dedicated to respiratory gas transport
oHemoglobin binds reversibly with oxygen
oNormal values
Males - 13–18g/100ml; Females - 12–16 g/100ml
Hemoglobin (Hb)
- Structure
oGlobin composed of 4 polypeptide chains
Two alpha and two beta chains
oHeme pigment bonded to each globin chain
Gives blood red color
oHeme's central iron atom binds one O2
oEach Hb molecule can transport four O2
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Document Summary
Blood: fluid connective tissue, plasma non-living fluid matrix, formed elements living blood cells suspended in plasma, erythrocytes red blood cells, or rbcs, leukocytes. White blood cells, or wbcs: platelets. Color varies with o2 content: high o2 - scarlet; low o2 - dark red ph 7. 35 7. 45. Average volume: 5 6 l for males; 4 5 l for females. Functions include: distributing substances, regulating blood levels of substances, protection. Transporting metabolic wastes to lungs and kidneys for elimination. Transporting hormones from endocrine organs to target organs. Maintaining body temperature by absorbing and distributing heat. Maintaining normal ph using buffers; alkaline reserve of bicarbonate ions. Maintaining adequate fluid volume in circulatory system. Preventing blood loss: plasma proteins and platelets initiate clot formation. Over 100 dissolved solutes: nutrients, gases, hormones, wastes, proteins, inorganic ions, plasma proteins most abundant solutes. Remain in blood; not taken up by cells. Functions: substance carrier, blood buffer, major contributor of plasma osmotic pressure.
