Unit 1 Exam - Bi122 GRCC Rierson

Blood

Continuously regenerated connective tissue

Blood is transported through

cardiovascular system

Basic functions of blood:

Transports gases, nutrients, wastes, and hormones

Heart

pumps blood

Arteries

transport blood away from heart

Veins

transport blood toward heart

Capillaries

allow exchange between blood and body tissues

Functions of Blood

Transportation, Protection,

(Assists in Maintaining Homeostatic Conditions): Body temperature, Fluid balance, Body pH

Functions of Blood: Transportation

• Transports formed elements, dissolved molecules and ions

• Carries oxygen (away from lungs) and carbon dioxide (toward lungs)

• Transports nutrients, hormones, heat and waste products

Functions of Blood: Protection

• Against pathogenic factors:

  • Leukocytes, plasma proteins, and other molecules related to the immune response

• Against blood loss:

  • Platelets and certain plasma proteins

Functions of Blood: Body temperature

• Blood absorbs heat from body cells (especially muscle)

• Heat released at skin blood vessels

Functions of Blood: Fluid balance

• Blood contains proteins and ions helping maintain osmotic balance

• Water is added to blood from GI tract

• Water lost through urine, skin, respiration

• Fluid is exchanged between blood and interstitial fluid

Functions of Blood: Body pH

• Blood absorbs acid and base from body cells

• Blood contains chemical buffers

Physical Characteristics of Blood

Color, Volume, Viscosity

Physical Characteristics of Blood: Color

Depends on degree of oxygenation:

• Oxygen-rich is bright red

• Oxygen-poor is dark red

Physical Characteristics of Blood: Volume

About 5 liters in adult:

• On average, males have slightly more than females (due to body size)

Physical Characteristics of Blood: Viscosity

Blood is 4–5 times thicker than water:

• Depends on amount of dissolved and suspended substances relative to amount of fluid:

  • This increases if erythrocyte number increases

  • This increases if amount of fluid decreases

Physical Characteristics of Blood: Plasma concentration of solutes

• E.g., proteins, ions, gases…

• Determines the direction of osmosis across capillary walls:

  • E.g., during dehydration plasma hypertonic: fluid drawn from tissues

Physical Characteristics of Blood: Temperature

Blood is 1°C higher than measured body temperature:

• Warms area through which it travels

Physical Characteristics of Blood: Blood pH

Slightly alkaline:

• pH between 7.35 and 7.45

• Crucial for normal plasma protein shape (avoiding denaturation)

Components of Blood

Formed Elements & Plasma

Formed elements of blood:

Erythrocytes, Leukocytes, Thrombocytes

Erythrocytes

(red blood cells) transport respiratory gases in the blood

Leukocytes

(white blood cells) defend against pathogens

Thrombocytes

(platelets) help form clots to prevent blood loss

Plasma

• Fluid portion of blood

• Colloid with suspended plasma proteins and dissolved solutes

Centrifuged Blood

Whole blood (plasma and formed elements) separated into parts by centrifuge

Components of Centrifuged Blood:

Plasma:

• Straw-colored liquid at top of tube

• About 55% of sample

Buffy coat

• Very thin (1%) middle layer with gray-white color

• Composed of leukocytes and platelets

Erythrocytes

• Lowest, red layer

• About 44% of sample

Hematocrit

• Percentage of volume of all formed elements (Packed Cell Volume)

• Clinical definition: percentage of only erythrocytes

• Adult males: 42–56%; females 38–46%

  • Testosterone causes more erythropoietin secretion by kidney

Composition of Plasma

Water (92%)

Plasma proteins (7%)

Dissolved molecules and ions (1%)

____ is an extracellular fluid

Plasma

Similar composition to interstitial fluid,

but plasma has higher protein concentration

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