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The Missing Loonie Riddle. Animals : From Cells to Systems. Agenda. Anticipation guide Cell differentiation/specialization Abnormal Development Chernobyl (video) Break (5 min) Types of tissues In class work. Anticipation Guide. 3.1 Cells and Tissues.
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Agenda • Anticipation guide • Cell differentiation/specialization • Abnormal Development • Chernobyl (video) • Break (5 min) • Types of tissues • In class work
3.1 Cells and Tissues • The adult human body is estimated to have between 75 to 100 trillion cells! • Some of these cells are non-specialized while most of the cells are specialized (i.e. differentiated)
Cell Differentiation/Specialization • There are 3 main factors that influence cell specialization • The contents of the cell’s cytoplasm • Environmental conditions • The influence of neighbouring cells • Let’s look at each of these factors individually
Factor 1: Influence of the Cytoplasm on Cell Specialization • In mitosis each daughter cell receives identical sets of chromosomes. • However, each cell will contain a different cytoplasmic content (i.e. larger vacuole, more ribosomes, etc) • This results in the production of different signals for cell specialization.
Factor 2: Environmental Influence on Cell Specialization • Some environmental factors that can impact cell specialization are: • Temperature • E.g. Siamese Cats dark feet, tails, ears and nose due to cold temperatures • Presence or lack of nutrients • Toxins
Factor 3: The Effect of Neighbouring Cells on Cell Specialization • Neighbouring cells tend to have the largest impact on cell specialization. • They send signals to nearbycells which alters their DNA. • E.g. Digit (finger) formationduring development.
The Effect of Neighbouring Cells on Cell Specialization • E.g. 2: 12 Day Old Chick Embryo
Abnormal Development • The environment plays a critical role in normal development of the embryo. • If exposed to toxins, contaminants, radiation, or other harmful chemicals the embryo may develop abnormalities. Cyclops lamb: VeratrumCalifornicum (contains cyclopamine)
Human Abnormal Development Approximately 6% of worldwide babies born each year are born with an abnormality! • With increasing abnormalities, it will be “normal” to have an abnormality.
From Cells to Tissues • When a group of cells come together to carry out a specific function they form a TISSUE • Animals have four main tissues: • Epithelial • Muscle • Nervous • Connective
Epithelial Tissue • Lines the inner and outer surfaces of the human body (including organs) • Functions of epithelial cells include secretion, absorption, protection and transcellular transport. • Can be subdivided into skin epithelia and columnar epithelia
Types of Epithelial Tissue • Skin Epithelia: Creates a barrier between the inside and the outside of the body • Mainly for protection • Columnar Epithelia: Found in the small intestine, stomach and glands. It functions to absorb nutrients and secrete mucus.
Muscle Tissue • Consists of elastic-like cells that contract. • Can be subdivided into skeletal muscle, smooth muscle, and cardiac muscle.
Types of Muscle Tissue • Skeletal Muscle: Connects to the bone allowing movement. • Voluntary • Smooth Muscle: Found along the walls of blood vessels and internal organs (i.e. oesophagus and stomach) • Involuntary • Cardiac Muscle: Found only in the heart
Nervous Tissue • Made of cells called neurons. Function to receive and conduct electrical signals. • Relay signals to the central nervous system (brain and spinal cord). • Detects and responds to external stimuli.
Connective Tissue • Tissue that functions to strengthen, support, protect, bind, or connect cells and other tissues. • Can be subdivided into Bone Tissue, Fat (adipose tissue), and Blood Tissue.
Types of Connective Tissue • Bone: Made of many cells enveloped in calcium. • Fat: A collection of large, tightly packed cells found under the skin and around organs. • Blood:A collection of red and white blood cells, platelets, and plasma.
Test Your Knowledge • Which tissue prevents harmful bacteria from entering your body? • Which tissues are responsible for supporting and forming bone? • Imagine you are opening a water tap in your washroom. Immediately after touching the water, you realized the water was boiling. Which tissues are involved in moving your hand away quickly? • Which tissue is responsible for controlling the contraction of blood vessels?
Homework/ In Class Work • Read pages 85-92. • Practice Questions 1,3, 4 (page 90)
Agenda • Story Time • Stem Cells • PluripotencyvsTotipotency • Use of Embryonic Stem Cells • Controversy of Stem Cells • Pros and Cons of Embryonic Stem Cells (T-Chart) • Different types of Stem Cells • In-class work/Assignment
Stem Cells • Analogous to the meristematic cells in plants • Are unspecialized non-differentiated cells
Totipotent Stem Cell Toti- : Means Total -potent : Means Potential • By combining the prefix and suffix we can make sense of the meaning of the word. • Totipotentcells are therefore cells that have the potential of forming all total cells possible
Pluripotent Stem Cells Pluri- : Means plural or multi -potent : Means Potential • By combining the prefix and suffix we can makes sense of the meaning of the word. • Pluripotentcells are therefore cells that can make many different types of cells (but not all).
PluripotentvsTotipotent Embryo (Day 5) Early Embryo Trophoblast Blastocyst Fertilized egg
Embryonic Stem (ES) Cells • Found in early embryo’s (<1 week old) • Are pluripotent • Are used by scientists to treat various illnesses and conditions
E.g. 1 Use of ES Cells • Cardiovascular disease • Lack of oxygen kills heart cells • Heart cells cannot replenish themselves • ES cells can be inserted into the heart to regenerate new heart cells
E.g. 2 Type 1 Diabetes • Cells in the pancreas that produce insulin (controls blood sugar) are attacked by the own body’s immune system • ES Cells help replenish insulin producing cells
Controversy • Attaining a sample of ES cells involves destroying an embryo. • These embryo’s are usually in vitro (fertilized in a test tube) Is it ethically right to kill an embryo for the sake of medical advancement?
Additional Types of Stem Cells Adult Stem Cells • Are tissue specific stem cells. (i.e. Neural stem cells can produce all types of nerve cells • Commonly used to restore bone marrow cells in patients that have received chemotherapy.
Additional Types of Stem Cells Fetal Stem Cells • Taken from fetus (10 weeks old) • Are tissue-specific Cord Blood Stem Cells • Taken from umbilical cord at birth • Used to treat the blood system after cancer treatments (i.e. chemo)
Additional Types of Stem Cells Induced Pluripotent Stem Cells (iPS) • Reprogramming of specialized cells (i.e. skin cells) into an embryonic stem cells. • Are pluripotent • Behave slightly different that ES cells.
Assigned Work • Reread section 3.1 • Answer questions #4-8 • Assignment • Create a newspaper article documenting one use (treatment) for embryonic stem cells. • The article should include the 5W’s and the How component. • Due Monday
E.g. Burn Victims and Stem Cells • Burned tissue takes up to 30 days to begin healing in patients with 2nd degree burns • By placing ES cells at the region that is burned using a spray on method, the recovery can be reduced by over 3 weeks.