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Chapter 40

bioa02 chapter 40

Biological Sciences
Course Code
Mary Olaveson

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Chapter 40
40.1 – Why must animals regulate their internal environments?
-the cells of multicellular animals exist within an internal environment of
extracellular fluid that bathes every cell of the body
ocells are protected from changes or harsh conditions in the external
-as multicellular organisms evolved, cells became specialized for maintaining
specific aspects of the internal environment
osome cells evolved to be the interface between the internal and the
external environments and to provide the necessary transport functions to
get nutrients in, move wastes out, and maintain appropriate ion
concentrations in the internal environment
-other cells became specialized to provide internal functions such as circulation of
the extracellular fluids, energy storage, movement, and information processing
-the maintenance of stable conditions in the internal environment homeostasis
oit is an essential feature of complex animals
oif physiological system fails to function properly, it is compromised, and
as a result cells are damaged and can die
-the activities of all physiological systems are controlled by actions of the nervous
and endocrine systems
-the desire speed set point
-the reading feedback information
-when the set point and feedback information are compared, any difference
between them is error signal
osuggest corrective actions
-effectors some components of physiological systems
othey effect changes in the internal environment
othey are controlled systems because their activities are controlled by
commands from regulatory systems
-regulatory system obtain, process, and integrate information, then issue
commands to controlled systems
osensor an important component of any regulatory system
provides the feedback information that is compared to the internal
set point
-negative feedback is the most common use of sensory information in
regulatory systems
oindicates that this feedback information causes the effectors to reduce or
reverse the process of counteract the influence that created an error signal
ois a stabilizing influence in physiological systems; it tends to return a
variable of the internal environment to the set point from which hit

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-positive feedback is also seen in some physiological systems
oamplifies a response increase the deviation from the set point
oregulatory system that use positive feedback urination, defecation,
sneezing, and vomiting
-feed forward information is to change the set point
oanother feature of regulatory system
oit takes precedence over the posted speed limit, and you change you set
point to a slower speed
-each physiological system is composed of discrete organs, such as the live, heart,
lungs, and kidneys, that serve specific functions in the body
othey are made up of tissues an assemblages of cells and there of only 4
kinds of tissues:
epithelial, connective, muscle, and nervous
-epithelial tissues are sheets of densely packed, tightly connected epithelial cells
that over inner and outer body surfaces
oact as barriers and provide transport across those barriers
oform the skin and line the hollow organs of the body
oit can secrete hormones, milk, mucus, digestive enzymes, or sweat
oit can also have cilia that move substances over surfaces or through tubes
ocan also provide information to the nervous system
ofiltration and transport are important functions of epithelial cells 
control what molecules and ions can leave the blood to enter the internal
environment or the urine
can selectively transport ions and molecules from one side of an
epithelial membrane to the other
othey have high rate of cell division to replace cells that die and are shed
-muscle tissues consists of elongated cells that con contract to generate forces
and cause movement
oare most abundant tissues in the body, and when animals are active,
muscles use most of the energy produced in the body
othree types of muscle tissues
skeletal, cardiac and smooth
skeletal muscles are responsible for locomotion and other body
movements such as facial expressions, shivering, and breathing
cardiac muscles makes up the heart and is responsible for the
heart beat and the pumping of blood
smooth muscles is responsible for movement and generation of
forces in many hallow internal organs such as the gut, bladder, and
blood vessels
-connective tissues are generally dispersed populations of cells embedded in an
extracellular matrix that they secrete
oprotein fibers are important tissue cells
odominant protein collagen

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it is the most abundant protein in the human body, representing
25% of total body protein
are strong and resistant to stretch, giving strength to the skin and
the connections between bones and between bones and muscles
oit fills spaces between organs that has a low density of collagen fibers
oelastin another type of protein fiber
can be stretched to several times its resting length and the recoil
lunges and large arteries contain elastin
ocartilage and bones are connective tissues that provide rigid structural
oin cartilage a network of collagen fibers is embedded in a flexible
matrix consisting of a protein, along with a specific type of cell called 
are resistant to compressive forces
provides structural support for flexible structures ears and noses
oin bones also contain many collagen fibers, but its is hardened by the
deposition of the mineral calcium phosphate
oadipose tissues a form of loose connective tissue
form and store droplets of lipids
is a major source of stored energy
serves to cushion organs
oblood is a connective tissue consisting of cells dispersed in an extensive
extracellular matrix blood plasma
is much more liquid than other connective tissues
-nervous tissues two basic cell types are neurons and glial cells
oneurons come in many shapes and sizes, and encode information as
electrical signals called nerve impulses
onerve impulses travel over long extensions of the neurons called axons
oneurons are involved in controlling the activities of most organ systems
oglial cells provide a variety of supporting functions for neurons
there are more glial cells than neurons in our nervous system
-organs include more than one kind of tissue, and most organs include all four
othe wall of a stomach is a good example
inner surface is lined with epithelial cells
beneath the epithelial cells is connective tissue
within this connective tissue are blood vessels, neurons, and glands
muscle tissues enable the stomach to contract to mix food with
digestive juices
-organ system a group of organs that function together to achieve a particular
physiological function or set of functions
ostomach is part of the digestive system
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