Transcript Anatomy, Physiology and Disease Chapter 3 The Cells: The Raw

Anatomy, Physiology and Disease
Chapter 3
The Cells: The Raw Materials and
Building Blocks
Overview of Cells
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Cells are formed from chemicals and structures
Cells are found in all living things
Some nerve cells can be 2 feet long or longer
Cells can be flat, round, thread like, or irregularly
shaped
7.5 trillion cells found in body work together to
allow for proper functioning of body
Figure 3-1
Various types of cells within the
human body
Cell Structure
 Certain
common traits that almost all cells
share:
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Nucleus
Organelles
Cytoplasm
Cell membrane
Figure 3-2
Cellular components
Cell Membrane
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Defined boundary that possesses a definite shape
and actually holds cell contents together, acting
as protective covering
 Allows material in and out of cell
 Selectively permeable because they choose what
gets in or out
 3/10,000,000 of an inch thick
Example: Electrolytes
Na Sodium
K
Potassium
Cl Chloride
Co2 Carbon Dioxide
Na & K Pump
Figure 3-3
The cell membrane
Na & K Pump
Transport Methods
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Moving things in and out of cell can be done in
two broad ways:
 Passive transport: requires no extra form of
energy to complete
 Active transport: requires some addition of
energy to make it happen
Transport Methods (cont’d)
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Passive transport can be divided into four types:
 Diffusion
 Osmosis
 Filtration
 Facilitated diffusion
Diffusion
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Most common form of passive transport in which
substance of higher concentration travels to
area of lesser concentration
 Examples:
 Adding packet of powdered drink mix to
pitcher of water
 Smell of classmate’s perfume filling room
 Necessary to move oxygen from lungs to blood
stream, or carbon dioxide from blood stream to
lungs
Figure 3-4
Two examples of diffusion
Osmosis
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Another form of diffusion in which water travels
through selectively permeable membrane to
equalize concentrations of a substance
 Dissolved substance called a solute
Osmosis cont
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Water tends to travel across a membrane to
equalize concentrations of a solute; ability of
substance to pull water toward area of higher
concentration called osmotic pressure
 The greater concentration of solute, the greater
osmotic pressure, or pull, it exerts to bring in water
Filtration
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Differs from osmosis in that pressure is applied
to force water and its dissolved materials across
membrane
 Similar to rush of people pushing through
turnstile during rush hour
 Example: pumping of heart, which forces blood
flow into kidneys, where filtration takes place
Figure 3-6 The process of filtration in the kidneys, where smaller
solutes such as the electrolytes sodium and potassium pass through
the membrane, while the larger blood protein and cells normally do not.
Facilitated Diffusion
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A variation of diffusion in which a substance is
helped in moving across the membrane, similar to
an usher helping you to your seat
 Glucose is the substance that is often passed into
our bodies
 It can be imagined as moving into an already
revolving door – once it steps into the door it is
pushed along by Insulin.
Pathology Connection: Cystic Fibrosis
 Incurable,
fatal genetic disease affecting
1/3000 Caucasian babies
Cystic Fibrosis (cont’d)
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Etiology: malformation in membrane channels
for chloride and sodium ions
 Sodium and chloride do not diffuse across cell
membrane as they normally would
 Fluid around cells becomes extremely salty
due to excess sodium and chloride
 Results in excessively thick mucus in
respiratory, digestive, and reproductive
systems; mucus can cause clogging in organs
Cystic Fibrosis (cont’d)
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S/S may include
 Difficulty breathing (SOB)
 Nutritional deficits due to decreased
absorption of nutrients
 Increased risk of respiratory infection
 Diabetes
 Infertility (especially in males)
Cystic Fibrosis (cont’d)
 RX:
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No cure; treatments help extend and improve
quality of life
Nutritional supplements
Antibiotics to prevent pneumonia
Mucus thinning drugs (Mucomyst-Ascetlsysteine)
With treatment today, average life span of patient
is 35 years
Cystic Fibrosis (cont’d)
 Diagnosis
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Prenatal genetic testing
Postnatal genetic testing
Testing pulmonary function
Testing amount of sodium in sweat
Pathology Connection: Diabetes Mellitus
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Lack of glucose transport into cells causes
several problems
 Lots of glucose hangs around in bloodstream,
causing big osmotic problems for cells
 Cells can’t make as much energy as they
need when glucose can’t be transported
Types of DM
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Type I results from the body's failure to produce
insulin. 5-10% of diabetics have type I diabetes.
Must take insulin to survive.
 Type II results from Insulin resistance, a
condition in which cells fail to use insulin
properly. Most Americans who are diagnosed
with diabetes have type 2 diabetes
 Gestational: Pregnant women who have never
had diabetes before but who have high blood
sugar (glucose) levels during pregnancy. Affects
about 4% of all pregnant women
Endocytosis
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Used by cells for intake of liquid and food when
substance too large to diffuse across membrane
 Examples:
 Phagocytosis: name for process if solid
particle being transported
 Pinocytosis: name for process if water being
transported
Exocytosis
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Transport of things out of cell
 Some cells produce substance needed outside
cell
 Once substance is made, it is surrounded by
membrane, forming a vesicle, and moves to cell
membrane
 Vesicle becomes part of cell membrane and
expels its load out of cell
Pathology Connection:
Familial Hypercholesterolemia
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Blood cholesterol too high; caused by poor diet
and exercise or inherited
 Normally low density lipoprotein (LDL or “bad
cholesterol”) binds to cholesterol, and allows it to
be carried into cells via endocytosis; once inside,
cholesterol used to make other lipids
Familial Hypercholesterolemia cont’d
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LDL doesn’t move into cells, and stays in blood;
causes 2 problems
 Too little cholesterol gets into cells, and cells
must make more cholesterol
 LDL that cannot get into cells hangs around in
blood; causes plaques in blood vessels which
can lead to blood clots, strokes, and heart
attacks
 RX with diet modifications and cholesterol
lowering drugs
 1/500 Americans have moderate form
Phagocytosis, Pinocytosis & Exocytosis
Cytoplasm
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Gel-like substance composed of water, nutrients,
and electrolytes, which looks a lot like white of
raw egg
 Required by cells for their internal environment
to thrive and function
Nucleus
“Brains” of cell
 Dictates activities of other organelles in cell
 Has double walled nuclear membrane
preventing materials from entering
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Nucleus (cont’d)
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Chromatin
 Contains deoxyribonucleic acid (DNA); DNA
contains blueprints, or specifications, for
creation of new cells
 Will eventually form chromosomes, which
contain genes
 Genes determine our inherited characteristics
Nucleus (cont’d)
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Nucleolus
 Spherical body made up of dense fibers found
within cell nucleus
 Major function is to synthesize ribonucleic
acid (RNA) that forms ribosomes
Ribosomes
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Organelles found on endoplasmic reticulum or
found floating around in cytoplasm
 Made of ribonucleic acid (RNA) and assist in
production of enzymes and other protein
substances needed for cell repair and
reproduction
 Can be considered “remodeler” of cell, taking
existing structure and maintaining and repairing
it
Centrosomes
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Act as building contractor, building new
structures as need arises
 Contain centrioles that are involved in division of
cell
 Centrioles are tubular shaped and usually found
in pairs
Mitochondria
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Tiny bean-shaped organelles, act as power plant
to provide up to 95% of bodies’ energy needs for
cellular repair, movement, and reproduction
 If cell needs more power, it increases number of
mitochondria in cell
 Liver cells, which are quite active, have up to
2,000 mitochondria in each cell
Mitocondria cont’d
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Contain special enzymes that help to take in
oxygen for use in producing energy
 Energy produced is in form of ATP (adenosine
triphosphate) created by mitochondria
Endoplasmic Reticulum
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Series of channels set up in cytoplasm that are
formed from folded membranes
 Has two distinct forms:
 One has sandpaper-like surface, with
ribosomes on it, called rough endoplasmic
reticulum; responsible for synthesis of protein
 Second form has no ribosomes and appears
smooth, called smooth endoplasmic
reticulum; synthesizes lipids and steroids
Golgi Apparatus
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Looks like a bunch of flattened membranous
sacs
 Once protein from the endoplasmic reticulum is
received, it further processes and stores it
 Takes processed protein to cell membrane
where it is released
 Salivary glands and pancreatic glands have
higher numbers of Golgi apparati because they
have higher level of secretion or storage
Lysosomes
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Organelles containing powerful enzymes that
take care of cleaning up intercellular debris and
other waste
 Lysosomes help keep us healthy; they destroy
unwanted bacteria by participating in process of
phagocytosis
Other Interesting Parts
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Vesicles: vans which take stuff & travel to other
sites within cell
 Cytoskeleton: provides shape to cell and allow
cell and its contents to be mobile
 Flagella: whip-shaped tails that move some
cells, like sperm, to other locations
 Cilia: hair-like projections located on outer
surface of some cells; move particles using
wavelike motion
Pathology Connection:
Organelle Disorders
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Lysosomal storage disorder
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Occur when lysosomes missing one of their
enzymes
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Results in some molecules not breaking
down and accumulating in cells
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Many kinds of lysosomal storage disorders
• All are genetic
• Most lack effective therapies
Pathology Connection:
Tay Sachs Disease
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Enzyme missing in lysosomes of nervous
system cells
As result, glycoproteins accumulate in cells in
nervous system
Build up causes inflammation and eventual
cellular destruction
Symptoms include mental regression,
dementia and paralysis appearing within first
year of patient’s life
Found mostly in Ashkenazi Jews: German
Jews
Tay Sachs con’t
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Diagnosis: appearance of cherry red spot on
back of patient’s eyes; abnormalities in startle
reflex
No treatment; disease generally fatal within
two or three years of onset
Availability of genetic test has decreased
incidence in recent years
Pathology Connection:
Cigarettes and paralyzed cilia
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Smoking causes cilia in respiratory tract to
become paralyzed
As a result, cannot keep lungs clean
Over time, can lead to chronic obstructive
pulmonary disease (COPD) and other smokingrelated lung problems
Passive smoking (second hand smoke
exposure) also increases risk of lung problems
Enzymes
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Facilitate important chemical reactions in body
 One way is by speeding up reactions
 Not used up by reactions that they facilitate;
instead, act like carrier molecules
 Very specific; each only facilitates (catalyzes)
certain reactions
Pathology Connection:
Phenylketonuria (PKU)
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Genetic condition; enzyme disorder
 Most common in Caucasians of Irish, Scottish, or
Scandinavian descent
 Patients missing enzyme: phenylalanine
hydroxylase
 Without enzyme, amino acid phenylalanine builds
up in cells
 Build up affects nervous system; causes
progressive mental retardation if not treated
Phenylketonuria (PKU) con’t
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Other signs include
 Light pigmentation of skin, hair and eyes
 Abnormalities of posture and gait
 Epilepsy
 Diagnosis
 Blood tests & genetic tests
 Every newborn in US routinely screened
Phenylketonuria (PKU) con’t
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Treatment: low phenylalanine diet includes
avoidance of high protein foods and products
sweetened with aspartame (NutraSweet™)
 Consequences of going “off diet”
• Children: cognitive defects
• Adults: depression, anxiety, or other
neurological changes
Pathology Connection: Cancer
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When body is healthy, cells grow in orderly
fashion; control system prevents cells from
reproducing too fast
 Sometimes conditions are altered that trigger
changes in way cells reproduce; this wild,
uncontrolled reproduction can lead to too many
cells being produced, creating a lump, or tumor
 Tumors can generally be either benign or
malignant !!!
Cancer con’t
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Benign tumors
 Slow growth
 Tend to push healthy cells out of the way
 Generally non–life threatening
 Malignant tumors
 Rapid growth
 Tend to invade healthy tissues
 Can enter blood or lymphatic system and start
new tumors in other parts of body; this kind of
spread called metastasis
Malignant Tumors
Staging Tumors
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Prognosis often determined by stage at
diagnosis; two basic strategies for staging
cancers
 Staging based on amount of metastasis
• Stage I: no cancer spread
• Stage II: spread to nearby tissues
• Stage III: spread to the lymphatic system
• Stage IV: spread to distant organs
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Diagnosis of cancer
 Imaging techniques (MRI, CAT, X-ray, etc.)
 Blood tests
 Biopsy (surgical examination of abnormal
tissue)
Treatment of cancer
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Four main types; typically 2 types of RX
 Chemotherapy: uses chemicals to kill rapidly
dividing cells
 Radiation therapy: uses energy to target
cancer cells
 Surgery: removes cancer cells from body
 Biological or immunotherapy: trains body’s
natural defenses to fight cancer cells
Microorganisms
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Four primary microorganisms
 Bacteria
 Viruses
 Fungi
 Protozoa
Bacteria
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Bacteria can be harmful, as in case of
pathogens, or can be harmless and essential for
life
 Harmless bacteria sometimes called normal
flora
 Certain bacteria in intestines help to digest
food
 Some help to synthesize vitamin K, needed
for blood clotting
3 Types of Cocci Bacteria
Viruses
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Infectious particles that have core containing
genetic material surrounded by protective
protein coat called a “capsid”
 Cannot grow, eat, or reproduce by themselves;
must enter another cell and use that cell for
energy to grow and reproduce
 Do not respond to antibiotics; can stay dormant
in body and become active later in life
Virus
Fungi
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Plural form of fungus; can be one-celled or multicelled organism; plant-like organisms with tiny
filaments, called mycelia, that travel out from cell to
find and then absorb nutrients
 Good fungi, like edible mushrooms, are harmless;
others can cause disease or death
 Fungi spread through release of “spores”
 Examples of fungal infections include athlete’s foot,
thrush, or candidiasis
Protozoa
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One-celled, animal-like organisms that can be
found in water and soil
 Diseases caused by swallowing them or from
being bitten by insects that carry them in their
bodies Ex: Malaria
Types of Protozoa
Pathology Connection:
How Microorganisms Cause Disease
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Bacteria
 Destroy body tissues:
 Destroy blood cells:
 Inhibit ribosomes
 Cause fluid loss
 Cause high fever
 Cause decreased blood pressure
 Increase blood clotting
 Cause fluid in the lungs
 Cause paralysis
 Signs
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and symptoms of bacterial infection
High fever
Rapid pulse
Rapid breathing
Abnormal, often foul-smelling discharge from
infected area
Pain at infection site
Swelling at infection site
Antibiotics
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Antibiotics used to treat bacterial infections
 Chemicals kill prokaryotic bacteria without
harming eukaryotic cells
 Most antibiotics produced naturally by other
microorganisms
Fungal (Non-bacterial infections)
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Fungal infections
 Spores are inhaled
 Spores enter body through open wounds
 Spores: tiny bodies resistant to environmental
changes (able to stay dormant until conditions
are just right)
 Most fungal spores do not cause disease in
otherwise healthy individuals; exception is fungal
infections of skin (such as athlete’s foot and jock
itch)
Fungal infections Cont
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Many fungal infections opportunistic (only infect
people with compromised immune systems or
other underlying disease)
 Symptoms of fungal infection vary depending on
location of infection
 Treatment is difficult
 Most anti-fungal drugs are highly toxic
 Many fungal infections are resistant to
treatment
Protozoan Infections
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Most protozoan infections caused by
 Ingestion of contaminated water
 Insect bites
 Many protozoans are parasites
Protozoan Infections Con’t
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Symptoms vary depending on type of protozoan
 Many are serious disease causing long term
debilitating illness; example: malaria, which is
transmitted by mosquitoes
 Some are relatively mild illnesses; example:
“beaver fever” caused by “Giardia,” a
protozoan that lives in streams and water
supplies contaminated by fecal matter