Download Cell Specialization and Levels of Organization

12/13/2016
Cell Specialization
Cell Specialization
• Scientists estimate there are between 75 and
100 trillion cells in the body of an adult human
• Three factors influence differentiation in
animal cells
– Contents of cell’s cytoplasm
– Environmental conditions
– Influence of neighbouring cells
Effects of Cytoplasm
• Mitosis ensures that daughter cells receive
identical sets of chromosomes
• Cytoplasmic contents may differ
– More storage vacuoles will allow the cell to use
more energy as it grows
Effects of Neighbouring Cells
• One of the biggest influences on what a cell
will become
• Substances produced by one cell can diffuse
through a neighbouring cell’s membrane
– Changes the expression of DNA
Effects of Environment
• Temperature and presence of nutrients can
explain why cells with identical genes will
develop differently
• Example: Siamese cats
Stem Cells
• Recall: Meristematic
cells in plants
• Animals have
similar cells called
stem cells
– An unspecialized cell
that can produce
various specialized
cells
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Stem Cells
Stem Cells
• Embryos have
totipotent stem cells
• Human stem cells
become less versatile
as they become more
specialized
– Can become any kind
of cell
• As the embryo
develops, stem cells
become pluripotent
– Can produce many
but not all cell types
Adult Stem Cells
• Only adult skin stem cells can give rise to new
skin cells
• Only bone stem cells can replace bone
Ethics of Embryonic Stem Cells
Medical Potential of Stem Cells
• Canadian researchers Dr. Ernest McCulloch
and Dr. James Till found that marrow
transplanted from a healthy animal could
restore blood cells in an animal that had
undergone radiation therapy
Ethics of Embryonic Stem Cells
• Embryonic stem cells are found in embryos
that are less than a week old
• In the lab these totipotent stem cells are able
to keep dividing for up to a year without
differentiating
– Can make any one of the 300 cell types found in
an adult human
• To harvest these cells the embryo must be
sacrificed
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Ethics of Embryonic Stem Cells
• Where should we draw the line between
– “Harvesting” embryonic stem cells which could
save thousands, if not millions, of lives
and
– Murdering a developing person
cells – tissues – organs – organ systems
• Our faith teaches us that the Holy Spirit is
present from the time of conception (egg
meet sperm)
LEVELS OF ORGANIZATION
Levels of Organization in a
multicellular organism
Levels of Organization
• Tissue
– A group of similar cells that perform similar
functions
– Blood, nervous tissue
• Organ
– A group of tissues that work together to perform a
specific function
– Muscles, eyes
Levels of Organization in a
multicellular organism
• Organ Systems
– A group of organs that perform closely related
functions
– There are 11 organ systems in the human body
– Can you name them?
Human Organ Systems
•
•
•
•
•
•
Integumentary
Muscular
Circulatory
Digestive
Reproductive
Endocrine
Skeletal
Nervous
Respiratory
Excretory
Immune
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Organ System
Organs Involved
Basic Function
Integumentary
Skin, hair, nails, glands
• Covers and protects body
• Glands help control body temperature
Skeletal
Bones, cartilage
• Supports body
• Allows movement
• Protects the body
Muscular
Skeletal muscle, smooth muscle, cardiac muscle,
tendons, ligaments
• Works with skeletal system to provide movement
• Moves materials within body
Digestive
Mouth, esophagus, stomach, pancreas, gall
bladder, liver, intestines, rectum
• Ingestion
• Digestion
• Absorption of nutrients
• Elimination of solid wastes
Respiratory
Nose, mouth, trachea, lungs, bronchi,
bronchioles, alveoli, diaphram
• Exchange of gases
Circulatory
Heart, blood vessels, blood
• Transportation of materials (such as oxygen,
nutrients, hormones, and wastes within the body)
Nervous
Brain, nerves, spinal cord
• Controls body functions
• Coordinates responses
Endocrine
Glands (pituitary, hypothalamus, thyroid,
adrenals, pancreas, ovaries, testes)
• Controls growth and development
• Controls metabolism
Excretory
Skin, kidney, bladder, ureter, urethra
• Elimination of wastes
Reproductive
Ovaries, fallopian tubes, vagina, uterus
Testes, epididymis, vas deferens, penis, urethra
• Reproduction
Lymphatic
White blood cells, thymus, spleen, lymph nodes,
lymph vessels
• Protects body from disease
• Circulates fluid called lymph
• Absorbs and transports fats
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