BIO 252 Anatomy and Physiology Module 2
AP 2– Blood Composition and Functions
2.1 – Blood Overview
Blood
● Single celled organisms do not need blood because they can obtain
nutrients directly from and excrete waste directly into their
environment
● Humans need blood because we have large, complex bodies that
require blood to deliver nutrients and excrete waste from the trillions of
cells we are made of
○ Heart pumps blood throughout the body in a network of blood vessels
■ Three components of the cardiovascular system
● Heart
● Blood vessels
● Blood– the medium of transport in the cardiovascular system
Components of Blood
● Blood is a fluid connective tissue
○ Made up of cellular elements and a fluid extracellular matrix
○ The cellular elements– referred to as formed elements– include…
■ Erythrocytes (red blood cells– RBCs)
● Most abundant blood cells
● Specialized cells essential for the transport of oxygen in the blood
■ Leukocytes (white blood cells– WBCs)
● Play a role in body’s defense mechanisms
● Five classes of Leukocytes, all with different functions
■ Thrombocytes (cell fragments) and Platelets
● Small, membrane bound cell fragments that contain enzymes and other substances
important for clotting
● Plasma
○ Fluid, extracellular matrix which is mostly water
○ Continuously suspends the formed elements and enables them to circulate throughout
the body within the cardiovascular system
■ Makes blood unique among connective tissues– because it is fluid
Physical Characteristics of Blood
● Color
, ■
○ Color changes of blood occur because hemoglobin is a pigment that changes color
depending upon the degree of oxygen saturation
■ Bright red– blood that has just taken up oxygen in the lungs
Darker red– blood that has released oxygen in the tissues
● Viscousity– measure of a fluid’s thickness or resistance to flow
○ Viscosity is influenced by the presence of plasma proteins and formed elements within
the blood
○ The greater the viscosity → the greater the resistance to flow
○ Blood’s viscosity is 5 times greater than water
■ The viscosity of blood has a direct impact on pressure and flow
● Temperature
○ Normal temperature of blood is ~100.4 F
■ Slightly higher than average body temperature
○ When blood flows through the vessels, they experience some friction and resistance
■ This friction and resistance is especially present as vessels age and lose elasticity
■ This friction produces heat– accounting for blood’s slightly higher temperature
● pH– measure of alkalinity or acidity of a solution by measuring the concentration of hydrogen
ions
○ Average pH of blood is about 7.4, but can range from 7.35 – 7.45 in a healthy person
■ Blood, therefore, is slightly more alkaline (basic) than pure water, which
has a pH of 7.0 ○ Blood contains numerous buffers that help regulate pH
● Volume
○ Blood volume constitutes approximately 8% of adult body weight
■ Adult males typically average about 5 to 6 liters of blood
■ Adult females typically average about 4 to 5 liters of blood
Major Functions of Blood
● Primary function– transport oxygen and nutrients to and remove wastes
from body cells
○ Moved through the vessels by the pumping action of the heart
● Other specific functions of blood include
○ Transportation
■ Nutrients from food are absorbed in the digestive tract
● Most of these travel in the bloodstream directly to the liver
● They are processed and then released back into the bloodstream for
delivery to body
cells
■ Oxygen from the air diffuses in the blood
● Oxygen moves from the lungs to the heart, which then pumps it out to
the rest of the body
, ■
■ Endocrine glands scattered throughout the body release hormones into the
bloodstream
● The bloodstream carries these hormones to distinct target cells
■ Blood picks up cellular wastes and byproducts and transports them to various
organs for removal
● Moves carbon dioxide to the lungs for exhalation from the body
● Transports various waste products to the kidneys and liver for excretion
from the body in the form of urine and bile
○ Defense
■ Many types of leukocytes protect the body from external threats
Some functions of these leukocytes include…
● Protecting against disease-causing bacteria that have entered the
bloodstream thru a wound
● Seeking out and destroying internal threats, such as cells with mutated
DNA that could multiply to become cancerous or body cells infected
with viruses
■ When damage to the cells results in bleeding, blood platelets and certain proteins
dissolved in the plasma interact to block ruptured areas of the blood vessels
involved– protecting body from further blood loss
○ Maintenance of Homeostasis
■ Regulates body temperature via negative feedback loops triggering homeostatic
mechanisms ● Rising core body temperature triggers an increase in
transport of blood from the core to the body periphery– which is typically
cooler
○ Blood passes through the vessels of the skin and heat is dissipated
out into the environment and the blood returning to the body’s
core is cooler
● Falling core body temperature triggers the diversion of blood away from
the skin to maintain a warmer body core
○ Extreme cases can result in frostbite
■ Blood helps maintain chemical balances in the body
● Proteins and other compounds in the blood act as buffers regulating the
pH of body tissues
■ Blood helps regulate the water content of body cells and distribution of fluid in
the body
2.2 – Blood Plasma
AP 2– Blood Composition and Functions
2.1 – Blood Overview
Blood
● Single celled organisms do not need blood because they can obtain
nutrients directly from and excrete waste directly into their
environment
● Humans need blood because we have large, complex bodies that
require blood to deliver nutrients and excrete waste from the trillions of
cells we are made of
○ Heart pumps blood throughout the body in a network of blood vessels
■ Three components of the cardiovascular system
● Heart
● Blood vessels
● Blood– the medium of transport in the cardiovascular system
Components of Blood
● Blood is a fluid connective tissue
○ Made up of cellular elements and a fluid extracellular matrix
○ The cellular elements– referred to as formed elements– include…
■ Erythrocytes (red blood cells– RBCs)
● Most abundant blood cells
● Specialized cells essential for the transport of oxygen in the blood
■ Leukocytes (white blood cells– WBCs)
● Play a role in body’s defense mechanisms
● Five classes of Leukocytes, all with different functions
■ Thrombocytes (cell fragments) and Platelets
● Small, membrane bound cell fragments that contain enzymes and other substances
important for clotting
● Plasma
○ Fluid, extracellular matrix which is mostly water
○ Continuously suspends the formed elements and enables them to circulate throughout
the body within the cardiovascular system
■ Makes blood unique among connective tissues– because it is fluid
Physical Characteristics of Blood
● Color
, ■
○ Color changes of blood occur because hemoglobin is a pigment that changes color
depending upon the degree of oxygen saturation
■ Bright red– blood that has just taken up oxygen in the lungs
Darker red– blood that has released oxygen in the tissues
● Viscousity– measure of a fluid’s thickness or resistance to flow
○ Viscosity is influenced by the presence of plasma proteins and formed elements within
the blood
○ The greater the viscosity → the greater the resistance to flow
○ Blood’s viscosity is 5 times greater than water
■ The viscosity of blood has a direct impact on pressure and flow
● Temperature
○ Normal temperature of blood is ~100.4 F
■ Slightly higher than average body temperature
○ When blood flows through the vessels, they experience some friction and resistance
■ This friction and resistance is especially present as vessels age and lose elasticity
■ This friction produces heat– accounting for blood’s slightly higher temperature
● pH– measure of alkalinity or acidity of a solution by measuring the concentration of hydrogen
ions
○ Average pH of blood is about 7.4, but can range from 7.35 – 7.45 in a healthy person
■ Blood, therefore, is slightly more alkaline (basic) than pure water, which
has a pH of 7.0 ○ Blood contains numerous buffers that help regulate pH
● Volume
○ Blood volume constitutes approximately 8% of adult body weight
■ Adult males typically average about 5 to 6 liters of blood
■ Adult females typically average about 4 to 5 liters of blood
Major Functions of Blood
● Primary function– transport oxygen and nutrients to and remove wastes
from body cells
○ Moved through the vessels by the pumping action of the heart
● Other specific functions of blood include
○ Transportation
■ Nutrients from food are absorbed in the digestive tract
● Most of these travel in the bloodstream directly to the liver
● They are processed and then released back into the bloodstream for
delivery to body
cells
■ Oxygen from the air diffuses in the blood
● Oxygen moves from the lungs to the heart, which then pumps it out to
the rest of the body
, ■
■ Endocrine glands scattered throughout the body release hormones into the
bloodstream
● The bloodstream carries these hormones to distinct target cells
■ Blood picks up cellular wastes and byproducts and transports them to various
organs for removal
● Moves carbon dioxide to the lungs for exhalation from the body
● Transports various waste products to the kidneys and liver for excretion
from the body in the form of urine and bile
○ Defense
■ Many types of leukocytes protect the body from external threats
Some functions of these leukocytes include…
● Protecting against disease-causing bacteria that have entered the
bloodstream thru a wound
● Seeking out and destroying internal threats, such as cells with mutated
DNA that could multiply to become cancerous or body cells infected
with viruses
■ When damage to the cells results in bleeding, blood platelets and certain proteins
dissolved in the plasma interact to block ruptured areas of the blood vessels
involved– protecting body from further blood loss
○ Maintenance of Homeostasis
■ Regulates body temperature via negative feedback loops triggering homeostatic
mechanisms ● Rising core body temperature triggers an increase in
transport of blood from the core to the body periphery– which is typically
cooler
○ Blood passes through the vessels of the skin and heat is dissipated
out into the environment and the blood returning to the body’s
core is cooler
● Falling core body temperature triggers the diversion of blood away from
the skin to maintain a warmer body core
○ Extreme cases can result in frostbite
■ Blood helps maintain chemical balances in the body
● Proteins and other compounds in the blood act as buffers regulating the
pH of body tissues
■ Blood helps regulate the water content of body cells and distribution of fluid in
the body
2.2 – Blood Plasma
