Download C. Organ Level

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Diagram 1 illustrates structural hierarchy in a pelican
A. Cellular level - Shows a single muscle cell in the bird’s heart. This cell's main
function is to contract, and the stripes in the cell indicate the precise alignment
of strands of proteins that perform that function
B. Tissue Level - a tissue is an integrated group of similar cells that perform a
common function. The cells of a tissue are specialized, their structure enables
them to perform a specific task – in this instance, coordinated contraction
C. Organ Level - An organ is made up of two or more types of tissues that
together perform a specific task. In this particular diagram, the heart is made
up of several tissues that work together to pump blood (e.g. cardiac tissue,
nervous tissue, etc.)
D. Organ System Level - consists of multiple organs that together perform a vital
body function. The other parts of the circulatory system are the blood and the
blood vessels: arteries, veins, and capillaries
E. Organism Level – An organism contains a number of organ systems, each
specialized for certain functions and all functioning together as an integrated,
coordinated unit. The pelican itself forms the final level of this hierarchy
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•An animal’s size and shape are fundamental aspects of form that significantly affect the
way an animal interacts with its environment
•The body plan of an animal is the result of millions of years of evolution
•Natural selection fits form to function by selecting the variations that best meet
the challenges of an animal’s environment
•The seal, penguin, and shark all have a streamlined, tapered shape, the result of natural
section adapting each to fast swimming in its dense, aquatic environment; an example of
convergent evolution
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•Epithelial Tissue, also called epithelium
•Occurs as sheets of tightly packed cells that cover body surfaces and line internal organs
and cavities
•Epithelial tissues are named according to the number cell layers they have and according to the
shape of the cells on their apical surface
•Simple epithelium - has a single layer of cells
•Stratified epithelium - has multiple layers of cells
•Pseudostratified epithelium - is single-layered but appears stratified because cells vary in
length
•Shapes of the cells that make up the epithelium may be:
•Squamous - flat like floor tiles
•Cuboidal - cube shaped like a dice
•Columnar – column shaped
•Diagram 2: Examples of different epithelial
A. Simple squamous epithelium - is thin and suitable for exchanging material by
diffusion. We find it lining our capillaries (smallest blood vessel) and the air sacs of our
lungs
B. Cuboidal epithelium - have cells with a relatively large amount of cytoplasm,
facilitating their secretion or absorption of material. Part B shows a simple cuboidal
epithelium forming a tube in the kidney
• Also found in glands such as the thyroid and salivary glands
C. Simple Columnar epithelium - lines the intestines
• It secretes digestive juices and absorbs nutrients
D. Pseudostratified ciliated columnar epithelium – forms a mucous membrane that line
the respiratory tract trapping dust, pollen and other particles in our air tubes
E. Stratified squamous epithelium - the many layers make it well suited for lining
surfaces subject to abrasion such as the outer skin and the esophagus, which can be
abraded by rough food
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Connective tissue in contrast to epithelium consists of a sparse population of cells
scattered through an extracellular matrix; binds and supports other tissues
There are 6 major types of connective tissues that shown illustrated in Diagram 3
A. Loose connective tissue – the most common connective tissue found in the
human body. Its matrix is a loose weave of fiber. Many of the fibers consist of
the strong ropelike protein collagen. (Above: loose connective tissue binding
skin to muscles)
B. Fibrous connective tissue – a matrix of densely packed parallel bundles of
collagen fibers, an arrangement that maximizes its nonelastic strength. Forms
tendons, which attach muscles to bone, and ligaments, which join bones
together
C. Adipose tissue – stores fat in large, closely packed adipose cells held in sparse
matrix fibers. This tissue pads and insulates the body and stores energy
D. Cartilage – a connective tissue that forms a strong but flexible skeletal material,
consists of an abundance of collagen fibers embedded in a rubber material.
Commonly surrounds the ends of bones, where it forms a shock-absorbing
surface. Also supports the nose and ear and forms the cushioning disks
between our vertebrae
E. Bone – has a matrix of collagen fibers embedded in a hard mineral substance
made of calcium, magnesium, and phosphate.
F. Blood – Its extensive extracellular matrix is a liquid called plasma that consists
of water, salts, and dissolved protein. Red blood cells, white blood cells, and
platelets are suspended in the plasma. Functions mainly in transporting
substances from one part of the body to another and in immunity
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Muscle tissue consists of bundles of long cells called muscle fibers and is the most
abundant tissue in most animals. Vertebrates have three types of muscle tissue illustrated
in Diagram 4:
A. Skeletal muscle – is attached to bones by tendons and is responsible for
voluntary movements of the body
B. Cardiac muscle – forms the contractile tissue of the heart.
C. Smooth Muscle - found in the walls of the digestive tract, urinary bladder,
arteries, and other internal organs. Responsible for involuntary body activities,
such as the movement of food throughout the intestines
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Nervous tissue senses stimuli and rapidly transmits information from one part of the an
animal to another. The structural and functional unit of nervous tissue is the nerve cell, or
neuron, which is uniquely specialized to conduct electrical nerve impulses.
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In all but the simplest animal, tissues are arranged into organs that perform specific
functions. The heart, for example, while mostly muscle, also has epithelial, connective, and
nervous tissues.
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Scientists are increasingly turning to bioengineering in their search for ways to repair or
replace damaged tissues and organs
One of the most successful tissue-engineering advances has come in the form of artificial, a
type of human-engineered tissue designed for everyone from burn victims to diabetic
patients with skin ulcers.
Figure 4: Shows a laboratory-grown bladder. In 2006, researchers reported the first
successful transplantation and long-term functioning of laboratory-grown bladders. This
initial study involved only seven individuals, but it showed that organ engineering is
possible.
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The endocrine system secretes chemicals, called hormones, that regulate body activities
such as digestion, metabolism, growth, reproduction, heart rate, and water balance
The skeletal system supports the body, protects certain internal organs such as the brain
and lungs, and provides the framework for muscles to produce movement
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The circulatory system delivers nutrients and oxygen (O2) to body cells and carries carbon
dioxide (CO2) to the lungs and metabolic wastes to the excretory organs, the kidneys.
The respiratory system exchanges gases with the environment, supplies the body with O2,
and disposes of CO2.
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The muscular system produces movement, maintains posture, and produces heat.
The integumentary system protects against mechanical injury, infection, excessive heat or
cold, and drying out.
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The lymphatic system returns excess body fluid to the circulatory system and functions as
part of the immune system
The immune system defends the body against infections and cancer
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The urinary system ( or excretory system) removes nitrogen-containing waste products
from the blood and regulates the chemical makeup, pH, and water balance of the blood
The digestive system ingests and breaks down food, absorbs nutrients, and eliminates
undigested material.
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The reproductive system produces gametes and sex hormones. The female system
provides organs to support a developing embryo and glands for producing milk
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The nervous system coordinates body activities by detecting stimuli, integrating
information, and directing the body’s responses
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X-Rays – were the first means of producing a photographic image of internal organs. X-rays
are a type of high-energy radiation that passes readily through soft tissues.
Computer tomography (CT) – the computer-assisted technique produces images of a series
of thin cross sections through the body
Magnetic resonance imaging (MRI) – takes advantage of the behavior of the hydrogen
atoms in water molecules. MRI uses powerful magnets to align the hydrogen nuclei, then
knocks the nuclei out of alignment with a brief pulse of radio waves. In response, the
hydrogen atoms give out faint radio signals of their own, which are picked up by the MRI
scanner and translated by computer into an image.
Positron emission tomography (PET) – is an imaging technology that differs from both CT
and MRI in its ability to yield information about metabolic processes at specific locations in
the body. A PET scanner pinpoints metabolic “hot spots” by highlighting the sites of most
intense radiation with a radioactive isotope.
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Structure of Skin – consists of two layers: the epidermis and the dermis
•The outer epidermis is a stratified squamous epithelium and serves to replenish
the skin cells that are constantly braded from the body surface
•The dermis is the inner layer of the skin. It consists of a fairly dense connective
tissue with many resilient elastic fibers and strong collagen fibers. The dermis
contains hair follicles, and blood vessels.
Functions of the skin
•The keratin-filled, tightly joined cells at the surface of the epidermis proved a
waterproof covering that protects the body from dehydrations and prevents
penetration by microbes
•Sensory receptors in the skin provide important environmental information to the
brain
•The profusion of small blood vessels and the 2.5 million sweat glands in the dermis
also facilitate the important function of temperature regulation
•The skin metabolically functions in the synthesis of vitamin D, which is required for
absorbing calcium. Adequate sunlight is needed for this synthesis
Hair and Nails – hair is flexible shaft of flattened, keratin-filled dead cells, which are
produced by a hair follicle. Hair insulates the bodies of most mammals. Fingernails and
toenails have protective coverings which are also composed of keratin. Nails facilitate fine
manipulation and scratching
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Figure 14: is a schematic model illustrating four of the organ systems of a compact,
complex animal. Each has a large, specialized internal exchange surface. We have placed
the circulatory system in the middle because of its central role in transporting substances
between the other three systems. The blue arrows indicate exchange of material between
the circulatory system and the other systems.
Actual, direct exchange does not occur between the blood and the cells of tissues and
organs. Body cells are bathed in a solution called interstitial fluid. Materials are exchanged
between the blood and the interstitial fluid and between the interstitial fluid and the body
cells. Materials must pass through interstitial fluid.
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Homeostasis – the ready state of body function; a state of equilibrium characterized by a
dynamic interplay between outside forces that tend to change an organism’s internal
environment and the internal control mechanisms that oppose such changes
Figures 15 and 16: Conditions may fluctuate widely in the animal’s external environment,
but homeostatic mechanisms regulate internal conditions, resulting in much small
fluctuations in the animal's internal environment
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Most of the control mechanisms of homeostasis are based on negative feedback, in which
a change in a variable triggers mechanisms that reverse that change
Diagram 5: When your body senses a rise in temperature above the set point, it activates
cooling mechanisms, such as the dilation of blood vessels in the kind and sweating. Once
body temperature returns to normal, your body shuts of these cooling mechanism. When
body temperature falls below the set point, warming mechanisms activate, such as
constriction of blood vessels to reduce heat loss and shivering to generate heat. Again, a
return to normal temperature shuts off these mechanisms
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