Topic 4: Tissues, organ Systems, and homeostasis (09052012 NK)
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Objectives
1) Name the four types of tissues.
2) Describe the location and the purpose
of Epithelial
tissue.
3) Describe the location and the purpose
of Connective tissue.
4) Describe the location and the purpose
of Muscle
tissue.
5) Describe the location and the purpose
of Nervous tissue.
6) Describe what an organ is.
7) Describe what an organ
system is.
8) what are the functions of skin.
9) How do multicellular organisms
maintain homeostasis?
10) Describe a typical positive feedback
response.
Useful
figures
4.1,2,3,
the 11 organ system figures 4.10 skin and 4.12 components of a negative
feedback control.
1. The function of the body dictates its structure.
A. The
human body is programmed to:
1) Maintain
internal operating conditions (temperature, salinity, pH)
within some tolerable range. (Homeostasis)
2) Locate
and acquire nutrients and dispose of waste (eat and poop)
3) Protect
itself against injury or attack from accidents, viruses, bacteria, and other
agents
4) Reproduce
and provide for the health and safety of our offspring during early development
5) Laugh
at bad jokes
B. Our
body is the sum of it’s smaller parts. The following is a list of the 4 levels of
organization in we humans
1) Tissues
(The 4 types are- epithelial, connective,
muscle, nervous) are
an aggregation of cells and extracellular substances functioning for a
specialized activity.
2) Various
types of tissues can combine to form functional units called organs, (like th heart, kidneys and brain)
3) Organs
may interact to form organ systems such as
the digestive system, where multiple organs work in
concert to perform a single function, like digestion.
4) From
molecules to cells to tissues to organs to organ systems to a body, Each part of the
body has properties that depend on its subunits.
C. The
structure that we see depends a lot on the function. Just like a racecar is sleek and sporty and
looks like it is designed for speed so to the parts of our body share a form
that is dictated by their function.
List of tissues and their subtypes
Epithelial: Membranous, Glandular |
Nervous Conductive, supportive |
Muscle Cardiac, skeletal, smooth |
Connective Proper, blood, bone, cartilage |
We will now cover the four types of tissues that make up the human
body
A. Epithelial tissue is commonly called epithelium
1) Cells
of the epithelium are linked tightly together: there may be one or more layers
2) One
surface is free and unattached(facing the outside of the body) and the other
adheres to a structure called the basement membrane: specialized
junctions form links between epithelial cells
3) The
4 types of epithelium are named according to their shapes
a)
Simple epithelium is a single
layer of cells functioning as a lining for body cavities, ducts, and tubes
b)
Squamous epithelium consists
of flattened cells, examples are found in the lining of the blood vessels
c)
Cuboidal epithelium has cube
shaped cells,: examples are found in glands that secrete substances
d) Columnar epithelium
has elongated cells: examples are found in the intestine
4) Stratified
epithelium has many layers--as in the human skin
5) Pseudostratified epithelium is a single layer
of cells that looks like a double layer, most of the cells are ciliated:
examples are found in the respiratory passages and reproductive tracts
6) Glandular epithelium
a) Glands
are secretory structures derived from epithelium in which goblet cells (mucus producing) are embedded
b) Glands
are classified according to how their products reach the site where they are
used
(1)Exocrine
glands often secrete their product through ducts to a free surfaces:
they secrete mucus, saliva, earwax, milk, oil
and digestive enzymes
(a) Simple exocrine glands have only a few
branches
(b)Compound
glands have many branches
(c) Apocrine
glands (e.g. mammary) include bits of gland cells in their secretions
(d)Holocrine glands (e.g. oil) whole cells are
released which may later release the secretions inside the duct
(e) Merocrine glands (e.g. salivary) do not
include cell elements in their secretions.
(2)Endocrine
glands have no ducts, but distribute their product (hormones) via the blood
B. Membranes made of epithelium (do not confuse this with the cell membrane J)
1) Mucus
membranes line the tubes and cavities of the digestive, respiratory, and
reproductive systems where embedded glands secrete mucus that act as lubricants
2) Serous
membranes such as those that line the thoracic cavity do not contain glands,
they also produce lubricants
C. Cell to Cell contacts in Epithelium (How cells are held together)
1) Epithelial
cells tend to adhere to one another by means of specialized attachment sites
a) Tight
junctions link cells of epithelial tissues to form seals that keep
molecules form freely crossing the epithelium, without tight junctions
solutions would flow around the cells into the body
b) Adhesion
junctions or desmosomes are like spot welds in tissues
subject to stretching (the bladder)
c) Gap junctions
link the cytoplasm of adjacent cells: they form communication channels.
2) Sites
of cell to cell contact are especially profuse when substances must not leak
form one body compartment to another
(certain parts of the body are designed to leak)
2. Connective tissues (this tissue fills up empty spaces, glues
other body tissue together, forms support)
A. General
characteristics of connective tissue
1) Most
connective tissue contains fibroblasts which are cells that secrete
fibers made of collagen or elastin
2) The
fibers are embedded in a jelly like ground substance, which forms
the extracellular matrix surrounding the
embedded cells
3) Depending
on the number of cells and the thickness of the ground substance connective tissue
can be liquid like blood or solid like bone.
B. Connective
Tissue Proper
1) Loose
connective tissue supports epithelia and organs and surrounds blood vessels
and nerves: it contains more cells and fewer, thinner fibers
2) Dense
irregular connective tissue has fewer cells and more fibers which are
thick: it forms protective capsules around organs
C. Specialized connective tissue
1) Dense,
regular connective tissue has bundled collagen fibers lying in parallel and
is found in ligaments (binding bone to bone) and tendons (binding
muscle to bone)
D. Cartilage and Bone
1) Cartilage
contains a dense array of fibers in a rubbery ground substance (matrix)
produced by chondroblasts, which mature into chondrocytes
located in lacunae.
a) Hyaline
cartilage has many small fibers: it is found at the ends of bones, in the
nose, ribs and the windpipe
b) Elastic cartilage, because of its
elastin component, is able to bend yet maintain its shape such as the external
ear
c) Firbocartilage
is a sturdy and resilient form that can withstand pressure such as in the
disks that separate the vertebrae
2) Bone is organized as flat plates and
cylinders, bones support and protect body tissues and organs: they also work
with muscles to perform movement
a) The
bone matrix is mineralized (calcium) and hardened, but includes little holes or
lacunae for the osteocytes (bone producing cells)
b) Compact bone appear to be very solid
and makes up the shafts and long bones and the outer regions of all bones
c) Spongy bone occurs inside bones and
includes large, marrow filled spaces
E. Blood and
adipose tissue
1) Blood
a) Blood
is a fluid tissue derived from connective tissue.
b) The fluid plasma contains suspended formed
elements: red blood cells (oxygen transport), white cells
(defense) and platelets (clotting).
c) Blood
transports oxygen, wastes, hormones and enzymes.
2) Adipose
tissue
a) Adipose
tissue cells are specialized for the storage of fat, which can be used as an
energy reserve and cushions to pad organs.
b) Adipose has a rich supply of blood vessels,
which serve as highways for the movement of fats to and from individual adipose
cells.
3. Muscle tissue
A. Muscle
tissue contracts in response to stimulation, then passively lengthens (does not
require energy) **** Note muscle
tissue can only pull, it cannot push *****
B. There
are three types of muscle;
1) Skeletal
muscle tissue attaches to bones (via tendons)
for voluntary movement: it contains striated (actin and myosin) multinucleated,
long cells (fibers which are often bundled together to form a “muscle”.
2) Smooth muscle tissue contains spindle shaped
cells with a single nucleus: it lines the gut, blood vessels and glands its
operation is involuntary.
3) Cardiac (heart) muscle is
composed of short, striated cells that can function in units due to the
contracting signal that passes from cell to cell by way of the gap junctions.
4. nervous tissue
A. Neutron
Structure
1) Neurons,
and associated neuroglia cells, are organizes as lines of communication
throughout the body.
2) Branched
dendrites pick up chemical messages and pass them to an outgoing axon
3) Communication between neurons is by chemical
neurotransmitters, such an acetylcholine.
4) A
nerve is a bundle of neuron processes conduct to and from the CNS.
B. Neuron
functions
1) Sensory
neurons pick up stimuli and conduct to the central nervous system
2) Motor
neurons conduct impulses to muscles and glands
5. Organ systems (11, you should know most of them already)
A. Many of the
more complex functions of the human body cannot be performed by a single tissue
alone. An Organ is a
structure composed of two or more tissue types joined together to perform a specific
function. However even this complex
organ cannot perform many of the general functions of the body.
B. Eleven
organ systems (integumentary, muscular, skeletal,
nervous, endocrine, circulatory, lymphatic, respiratory, digestive, urinary,
and reproductive) sorry just memorize the. These all contribute
to the survival of all the living cells of the body. We will be covering each of these organ
systems for the remainder of the class.
C. The
holes in the body are as important as what makes up the body. The major cavities of the human body are: cranial,
spinal, thoracic, abdominal, and sometimes pelvic. They provide a location for many of the organ
systems, so that these systems can move and act independently of the rest of
the body.
6. The Skin:
What is it and how does it work and why it is important
A. Humans have an outer covering called the integument,
which includes the skin and the structures derived form epidermal cells such as
nails.
B. Skin
function
1) The
skin covers and protects the body form abrasion, bacterial attack, ultraviolet
radiation and dehydration.
2) It helps control internal temperature.
3) Its vessels serve as blood reservoir for the
body.
4) The skin produces vitamin D.
5) Its
receptors are essential in determining environmental stimuli. Touch, vibration, pain and temperature.
6) It
regulates the movement of substance into and out of the body or somatic system.
C. Skin
Structure
1) Epidermis
refers to the thin, outermost layers of cells consisting of stratified, Squamous
epithelium
a) Keratinization of epidermal cells of the stratum corneum turns them into dead bags of keratin, a waterproofing protein.
b) Three
pigments--melanin, hemoglobin, and carotene--contribute to skin
color. Dermis, the ticker portion
of the skin underlying the epidermis, is mostly dense connective tissue
(1)Blood
vessels, lymph vessels, and nerve endings are located here
(2)Sweat
glands secrete a fluid (mostly water with a little dissolved salt) that is
useful in regulating the temperature of the body
(3)Oil
(sebaceous) glands function to soften and lubricate the hair and skin: acne is
a condition in which the ducts become infected by bacteria
(4)Hairs
are flexible structures rooted in the skin and projecting above the surface,
growth is influence by genes, nutrition ,a d hormones
(5)As
the body ages, epidermal cells divide less often, skin becomes thinner, more
susceptible to injury, drier and less elastic.
7. Homeostasis and Systems Control
A. The
internal environment
1) The
trillions of cells in our bodies must be continuously bathed in fluid that
supplies nutrients and carries away metabolic wastes.
2) The
extracellular fluid consists of interstitial fluid (between the
cells and tissues) and plasma (blood fluid).
3) The
component parts of an animal work together to maintain the stable fluid
environment required for life
B. Mechanisms
of Homeostasis
1) Homeostatic
mechanisms operate to maintain chemical and physical environments within
tolerable limits these are often called the controlled variable and can include
a) Blood
pressure
b) Body
temperature
c) Blood
glucose
2) Homeostatic
control mechanisms require three components:
a) Sensory
receptor cells detect specific changes in the environment
b) Integrators
or control centers (brain and spinal cord) act to direct impulses to the
place where a response can be made
c) Effectors
(muscles and glands) perform the appropriate response
3) A
common homeostatic mechanism is negative feedback.
a) It
works by detecting a change in the internal environment that brings about a
response that tends to return donations to the original state.
b) It
is similar to the functioning of a thermostat in a heating/cooling system.
4) Positive feedback mechanisms may intensify the original
signal: sexual arousal is an example, childbirth and blood clotting.
a) It
is important to note that positive feedback is not a mechanism for maintaining
homeostasis.
Possible assignments: things
to think about
1. What are the typical parts of a tissue?
2. What distinguishes one type of tissue from another?
3. Why is blood (a liquid considered) a connective tissue?
4. Why are organ systems necessary?
5. Is one organ system more important than any others?
6. Rising blood sugar levels after a meal normally trigger insulin secretion, which in turn causes glucose to be converted to glycogen for storage. How is this similar to the response of an air conditioner thermostat to rising room temperature
7. How would you answer someone who says, “people in the tropics have such dark skin because they are out in the sun a lot making their skin tan fast and heavily.”
Multiple Choice Questions: Click on the revolving arrow to go to the study link
Click below to see the
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1. A tissue can be described as a number of different types
of cells that come together to perform a common function. Which of the following tissues are correctly
matched with their functions?
A. Epithelial tissue forms a protective coating on most organs and is the place where
nutrients move in and out of various parts of the body
B. connective tissue provides fillers for
other tissues and organs it supplies nutrients and protects various organs
C. muscle tissue responds to various stimuli
and becomes longer in response
D. Support tissue is like the electrical
wiring of the body. It transfers a
stimulus from one portion of the body to the other.
E. Adipose tissue makes up the thinking
organs like the brain
2. What type of epithelial tissue typically forms single
layers of cells that line body cavities, ducts and tubes?
Simple epithelium |
Cuboidal epithelium
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Squamous epithelium |
Columnar epithelium |
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3. Which of the following would be a significant difference between epithelial and connective tissues?
A. Only Epithelial tissues have cells
B. Only epithelial tissues have a ground substance
C. Only epithelial tissues are arranged in sheets with special junctions between cells that are side by side
D. Only connective tissues have a ground substance
E. Only connective tissues have cells
Review epithelial Review connective
4. Which of the following activities can be performed by
muscle tissue
A. Provides a soft
substance that can be worked on
B. When placed between two blocks it will pull the blocks together
C. When placed between two blocks it will push the blocks apart
D. Will conduct
a signal form one part of the body to another.
E. Will store
food and form a cushion with the organs.
Review
Muscle activity
5. The outermost layer of cells that make up the skin is
called
A. The epidermis and it is made up of simple epithelium
B. The epidermis and it is made of squamous epithelium
C. The dermis and it is mainly dense connective tissue
D. The melanin
within this layer gives the skin its color
E. Hemoglobin it is made of squamous epithelium
Answers 1) a,b,d 2) a 3)c,d 4)b 5) b
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