Cells, Tissues, and Organs Unit PDF

**[Types of Organisms (2 types)]** 1. unicellular -- 1-celled organisms e.g. amoeba, paramecium 2. multicellular -- many-celled organism e.g. plant, animal, human **[The Cell Theory (3 main points)]** 1. the cell is the basic building block that makes up all organisms 2. cells carry out all...

**[Types of Organisms (2 types)]** 1. unicellular -- 1-celled organisms e.g. amoeba, paramecium 2. multicellular -- many-celled organism e.g. plant, animal, human **[The Cell Theory (3 main points)]** 1. the cell is the basic building block that makes up all organisms 2. cells carry out all organism\'s functions 3. all cells are made from other cells e.g. mitosis, meiosis **[Common Features to all Cells]** 1. all cells are surrounded by a membrane ( a thin outer covering) 2. all cells use DNA to carry genetic info. 3. All cells use similar biochemistry e.g. ways to make energy 4. all cells have a size limitation e.g. can\'t be too big or small **[Why do Cells have a Size Limitation?]** - If cell too big biochemical reactions can\'t occur; therefore, cell dies - if cell too small it can\'t handle the traffic  needs of what must enter/exit the cell - control centre of the cell (nucleus) can control up to  a certain cell size e.g. 1 teacher can control 30 students but not 1000 **[Cell Types (2)]** 1. plant cell 2. animal cell **[Parts & Functions of the Animal Cell]** **cell membrane** -- outer covering of cell. It holds the cell together and controls what enters/exits the cell **cytoplasm** -- liquid part of the cell in which organelles float (**organelles** are the tiny organs found in the cell). This is where nutrients are absorbed, transported and processed **flagellum** -- a whip-like tail attached to some cells which acts as a propeller to move the cell around **nucleus** -- the control centre of the cell. It contains genetic info. Which tells the cell what to do and when to do it (called DNA). The DNA is found on thread-like structures called chromatin. When cells reproduce themselves the chromatin becomes thicker (more like spaghetti then thread) and is now called chromosomes. Each chromosome is made up of genes that determine a specific trait of a person e.g. eye colour. Because every cell in your body is identical they all contain the same genes. **Nucleolus** -- dense centre of the nucleus **vacuole** -- holding tanks that contain things that need to be broken down or removed from the cell e.g. food, waste **mitochondrion** -- powerhouse of the cell where energy for the cell is made via cellular respiration. It\'s the largest organelle of the cell. **Cellular respiration** -- breaking down sugar in food to make energy that the cell can use C~6~H~12~O~6~ + O~2~ → CO~2~ + H~2~O + energy **ribosomes** -- make proteins. Proteins make up cell structures, help in chemical reactions (enzymes), are needed in cell growth and cell reproduction. The nucleus tells the ribosome which protein the cell needs. Ribosomes can attach to other structures or float freely in the cytoplasm **rough endoplasmic reticulum** -- (rough ER) makes proteins to be used outside the cell (called rough because ribosomes are attached) **smooth endoplasmic reticulum** -- (smooth ER) makes steroids (called smooth since no ribosomes attached) **Golgi Apparatus** -- (Golgi Complex) packaging station. It packages proteins made by the rough ER that need to be transported in/out the cell. The packages are called vesicles. They are like vacuoles only smaller. **Lysosomes** -- made by the golgi apparatus. They contain digestive enzymes to break down contents in vacuoles e.g. food. Also, if a bacteria enters the cell the lysosome will surround it and digest it. **Centriole** -- helps in cell division **nuclear membrane** -- outside covering of nucleus that helps regulate what goes in/out of nucleus **microtubules and microfilaments** -- used for structural support and cell movement **[Parts & Functions of the Plant Cell]** - animal and plant cells are very similar in parts: both have cell membranes, mitochondrion, golgi apparatus, nucleus, nucleolus and vacuole - unlike animal cells, however, plant cells can make their own food via photosynthesis **cell wall** -- outside of cell membrane made of a stiff material called cellulose. It gives the cell support and protects it. Gases, water and minerals enter/leave wall via tiny openings **plastid** -- responsible for the colour of plants e.g. chloroplast **chloroplast** -- a plastid containing green pigment called chlorophyll which helps plants with photosynthesis **photosynthesis**- process occurring in the chlorophyll (within the chloroplast) whereby plants make their own food using the sun, CO~2~ from the air and water to make glucose (a sugar) CO~2~ + H~2~O + sunlight → C~6~H~12~O~6~ + O~2~ **vacuoles** -- animals cells have many small vacuoles but plant cells have 1 large vacuole. This vacuole is filled with water. Sugar, minerals and proteins **golgi apparatus** -- function like animal cell but also makes parts for the cell wall **[Microscopes]** **[Calculating Magnification]** Ocular Power x Objective Power = Total magnification Example: If an object is viewed through an ocular lens of 15X and a medium objective lens of 10X, calculate the total magnification. Ocular Power x Objective Power = Total magnification 15X x 10X = 150X Therefore, the total magnification of the specimen seen is 150X. (150 times bigger) **[DNA, RNA and Protein Synthesis]** DNA = deoxyribonucleic acid - DNA controls the production of proteins - DNA is made up of 2 strands with nucleotides that are wound together in a double helix (twisted ladder) - Nucleotides are bound together (from 1 strand to another) by a hydrogen bond so that the strands stay together. Hydrogen bonds are weak and can be easily broken - T,A,C,G are examples of nucleotide bases **[DNA Nucleotide Bases (4 types)]** - they function mainly in the nucleus of cells - Adenine (A), Thymine (T), Cytosine (C ), Guanine (G) - On the DNA strands only certain bases can bond together. This is called base-pairing. - Base pairs are as follows: A always pairs with T, and C always pairs with G (or vice versa) Therefore: **[Structure of DNA Nucleotides]** 1. a sugar called deoxyribose 2. a phosphate 3. a nitrogen base  - three nucleotides in a row on a strand of DNA for 1 amino acid - proteins on our body are made from a string of amino acids **[RNA Structures]** RNA = ribonucleic acid - RNA structure is similar to DNA structure except the strands are shorter and the nucleotide thymine (found in DNA) is replaced by Uracil (U) in RNA **[RNA Nucleotide Bases]** - function mainly in the cytoplasm of the cells - Adenine (A), Uracil (U), Cytosine (C ), Guanine (G) - A DNA strand is used to make an RNA strand so base pairing is as follows: A will always pair with U, C always pairs with G and T (from DNA strand) will pair with A or vice versa **[Structure of RNA Nucleotides]** 1\. a sugar called ribose 2\. a phosphate 3\. a nitrogen base +-----------------------------------+-----------------------------------+ | DNA | RNA | +===================================+===================================+ | Deoxyribonucleic Acid | Ribonucleic Acid | +-----------------------------------+-----------------------------------+ | A nucleic acid | A nucleic acid | +-----------------------------------+-----------------------------------+ | Contains sugar deoxyribose | Contains sugar ribose | +-----------------------------------+-----------------------------------+ | Nucleotide base pairing | Nucleotide base pairing | | | | | A\-\-\-\--T | A\-\-\-\--U | | | | | C\-\-\-\--G | C\-\-\-\--G | +-----------------------------------+-----------------------------------+ | Double Helix shape | Different Shapes | +-----------------------------------+-----------------------------------+ **[DNA Replication]** - each strand of DNA serves as a template to make an exact copy of the original **[Basis of Heredity]** sex cells -- (also called germ cells) contain 23 chromosomes in humans. They have half the genetic material of the parent cell produced in meiosis. e.g. sperm, egg in humans body cells- (also called somatic cells) all contain 46 chromosomes when produced in mitosis **[Mitosis and Cell Division]** Cell cycle -- sequence of events from 1 division to another Cell Cycle: (2 parts) 1. Cell division - division of nucleus happens during mitosis (prophase, metaphase, anaphase, telophase) M phase - division of cytoplasm called cytokinesis 2. Interphase - period of time between cell divisions. The cell takes in nutrients, grows, and conducts normal cell functions. It has 3 phases: G~1\ (~cell growth), S (DNA replication), G~2~ (preparation for mitosis) (see textbook pg 29) **[Importance of Mitosis and Cell Division]** - mitosis ensures that each newly created cell contains a complete set of chromosomes (genetic info - for unicellular organisms mitosis is a method of reproduction - for multi-cellular organisms mitosis is essential for growth, maintenance and replacement of body parts **[Tissues, Organs and Organ Systems]** - each cell in your body is identical and has all of the genetic info. To make every protein in your body **but** no cell does this. Instead cells specialize and produce only the proteins needed for that cell (e.g. skin cell produces only proteins used by the skin.) **[Cell Replacement]** - new cells replace old or damaged cells - regeneration is the regrowth of body parts. This is more common in plants than animals. For example, in humans liver cells will regenerate to a certain point but brain and nerve cells will not **[Regulation of Mitosis and Cell Division]** - length of time between cell divisions depends on: species, cell type and age of species (e.g. babies will experience many more cell divisions than an adult because of an increased growth rate) - chemicals called growth factors usually begin mitosis **[Abnormal Cell Division]** - when a cell loses the ability to respond to factors that regulate its growth, it will grow and divide uncontrollably and form a tumor tumor -- a dense mass of unregulated cells metastic tumor -- starts in one organ and then spreads to another malignant tumor -- are life threatening and may spread to other parts of the body even if removed. Can spread quickly via the bloodstream. Spreading can be delayed/prevented via drugs or radiation benign tumor -- easily removed and does not spread to other parts of the body. If not removed it will continue to grow; as a result, it could cause pain or interfere with the function of an organ. **[Cancer]** cancer -- a condition where malignant cells invade and destroy body tissues. It\'s usually fatal if left untreated because cancer cells do not stop dividing carcinogen -- cancer causing agent e.g. pesticides **[Most Common Types of Cancers]** 1. lung (2) breast (3) prostate (4) colon/rectal **[Main Types of Carcinogens]** 1. radiation (2) viruses (3) chemicals - carcinogens alter a cell\'s DNA so it does not respond to the normal "stop dividing" signs. Because cancer cells absorb nutrients faster than normal cells, they become stronger and out compete normal cells for space. Normal cells Cancer Cells --------------------------------------------------------------------------- -------------------------------------- Regular shape and size Irregular shape and size Normal structures found in mitosis Abnormal structures found in mitosis Cells divide only when mature Cells divide before maturity Cells grow beside each other without touching (called contact inhibition) Cells grow all over each other **[Meiosis]** diploid cell -- (2n) cell with 2 sets of chromosomes e.g 46 chromosomes in a human body cell haploid cell -- (1n) 1 set of chromosomes e.g. 23 chromosomes in a human sperm cell homologous pairs -- matching pairs of chromosomes in a diploid cell **[Mitosis vs. Meiosis]** 1. mitosis involves a single replication of chromosomes by a single division of nucleus and cytoplasm. In meiosis a single replication is followed by 2 divisions and 2 cell divisions 2. mitosis results in 2 diploid cells whereas meiosis results in 4 haploid cells 2. in meiosis there\'s a pairing of homologous chromosomes. This does not happen in mitosis **[Regeneration]** regeneration -- process whereby a body part is replaced or regrown - the salamander can regrow amputated limbs, tails, lenses in the eyes, and parts of the heart - humans have a limited ability to regenerate e.g. liver cells, skin cells. Did you know that an amputated finger tip that is cleaned and covered with a simple dressing can regenerate? The new fingertip has the same fingerprint pattern and sensations of the original. **[The Process of Cell Specialization]** cell specialization -- cell develop in different ways to perform particular functions e.g. cell becomes skin cell stem cells -- unspecialized cell - stem cells can form into specialized cells e.g. nerve cells, blood cells, muscle cells when exposed to proper environmental conditions, or they can remain unspecialized and actively divide for long periods **[Stem Cells (2 types) see pg 41 Fig 1.41]** embryonic stem cell -- come from a embryo and can specialize into any type of cell since it has not differentiated. The controversy comes from the destruction of the embryos to get the stem cells adult stem cells -- come from an adult but limited to the type of cell that it came from since it has already differentiated e.g. brain cells can only reproduce brain cells - current research involves use of stem cells in the treatment of cancer, Parkinson\'s disease, Alzheimer\'s disease, stroke, heart disease, diabetes and rheumatoid arthritis **[Meristematic Cells see pg 41 Fig 1.42]** - meristematic cells are stem cells found in plants. They are found at the root tip and in the stem. They are continually producing new cells of various types. **[Levels of Organization in an Organism]** **Cell** e.g. skin cell, muscle cell ↓ **Tissue** group of cells that function together to perform a task e.g. skin tissue, muscle tissue ↓ **Organ** group of tissues that perform a specific function  e.g.heart, skin ↓ **Organ System** many organs functioning together for a purpose  e.g. digestive system, respiratory system ↓ **Organism ** e.g. human, dog **[Animal Tissues see pg 43 Table 1.5]** **[Epithelial and Connective Tissue]** epithelial tissue -- cells that form a protective barrier. They can be one cell to many layers thick connective tissue -- joins other tissues together e.g. tendons, ligaments, bones, cartilage and blood - tendons connect muscle to bone -  ligaments connect bone to bone - blood is made of plasma, red blood cells, white blood cells and platelets - red blood cells contain hemoglobin that absorbs and releases oxygen. White blood cells protect the body from bacteria/viruses and fight infection. Platelets help in clotting blood. **[Muscle and Nervous Tissue]** **[Muscle Tissue (3 types)]** 1. skeletal -- muscle that moves bone. They are voluntary muscles because we move them of our own accord e.g. arm muscles, leg muscles 2. smooth -- found in blood vessels, stomach. They are involuntary muscles since they move without our consciousness 3. cardiac -- found in the heart. They are involuntary muscles as well. Nervous tissue -- made of nerve cells capable of creating messages (impulses) and transmitting them throughout the body. **[Plant Tissues (4 type)]** **[see pg. 44 Table 1.6 and pg. 43 Fig. 1.44]** All plant tissues form from groups of meristematic cells called meristematic tissue 1. epidermal tissue 2. vascular tissue 3. ground tissue 4. meristematic tissue **[\ Epidermal and Ground Tissue]** epidermal tissue -- forms protective outer covering, allows the exchange of gases in/out of the plant via the stomata ground tissue -- in the stem it provides strength and support, in the roots it stores food and water, in the leaves photosynthesis takes place here   **[Vascular Tissue]** xylem -- responsible for movement of water and minerals from root to stem to leaves where these substances are used in photosynthesis phloem -- transports the sugar made in photosynthesis from leaves to other parts of plant where it\'s used to provide energy for cellular processes **[Animal Organs]** **[Skin see pg 56 Fig. 2.3]** - largest organ in the body - protects inner cells from damage, acts as a defense against disease organisms, insulates, releases heat and excretes bodily wastes **[Lungs see pg 57 Fig. 2.5]** - allow you to breath in O~2~ and exhale CO~2~ - an adult lung is about 1kg (half of the mass is blood) O~2~→ nose or mouth →pharynx →trachea →bronchi →bronchiole →alveoli - O~2~ goes from the alveoli through the capillaries into the blood. CO~2~ travels from the bloodstream, across the alveoli and back into the respiratory system until it exits the mouth/nose **[Heart see pg 57 Fig. 2.6]** - pump that supplies blood to all parts of the body - adult heart is about 300g and the size of a fist - in an average lifetime, the heart beats about 3.5 billion times - the heart has 4 chambers: left atria & left ventricle -- pump O~2~ rich blood through the aorta to the rest of the body right atria & right ventricle -- pumps blood to lungs so that it can get oxygen **[Organs of Digestion see pg 65 Table 2.1]** - digestion is breaking down food so the body can use it food →mouth →esophagus →stomach →small intestine →large intestine→ rectum →anus - mouth produces enzymes to break down sugars - stomach produces digestive juices to churn and digest proteins - small intestine finishes digestion of sugars and absorbs nutrients into bloodstream - large intestine absorbs water from waste to be expelled peristalsis -- wave-like contractions that move food along the digestive tract **[Plant Organs]** **[Roots see pg 59 Fig 2.9]** - anchor plant in soil - collect water from surrounding soil and transport it to the stem and store food that is made in other parts of the plant **[Leaf see pg 59 Fig 2.10]** Site of photosynthesis in the mesophyll layer 1. waxy cover made of cutin, prevents water loss 2. protection, few or no chloroplast, produces cutin 3. where photosynthesis occurs 4. temporary food storage, exchange of gases (O~2~, CO~2~) between leaf and world 5. protection 6. control gas exchange between leaf and world **[The Stem]** - stem has 2 main functions: (1) transport water/nutrients throughout plant (2) supports leaves and flower - usually contains a waxy cuticle that reduces water loss **[The Flower see pg 60 Fig. 2.11]** - flower is the reproductive structure of the plant - main function of the flower is to produce seeds through sexual reproduction - flower\'s male organs: stamen with an anther at the tip (the anther produces the pollen) - flower\'s female organs: pistil consisting of ovary, style stigma - female sex cells are eggs found in the ovary, male sex cells are pollen - the fertilized egg becomes a seed - some seeds are surrounded by flesh (the ovary of the plant) e.g. tomato **[Organ Systems see pg 67 Table 2.2]** organ system -organs functioning together for a specific function e.g. digestive system **[Integumentary System]** - made up of skin and accessory structures e.g. hair, nails, horns, hooves, antlers, quills, claws - various glands include sweat glands, sebaceous (oil) glands, scent glands - sweat is secreted to cool the body - sebaceous glands produce oil that lubricates, waterproofs and helps prevent skin infections. If plugged with dirt and excess oil a blackhead forms **[Digestive System]** - food passes through the system to be broken down (digested) so the nutrients can be absorbed - absorption of nutrients takes place mainly in the small intestine **[Comparing Digestive Systems]** **Earthworms see pg 74 Fig. 2.30** - the earthworm takes dirt through its mouth and pushed by muscular contractions to the esophagus and crop. Food then moves into the gizzard which grinds the food into smaller pieces. The food is then pushed into intestines where digestion and absorption of nutrients occurs. Waste is expelled via anus **Fish see pg 75 Fig. 2.31** - perch\'s mouth has sharp teeth to grasp its prey which then passes to the esophagus and stomach where the food is digested. A pyloric caecum further breaks down the food and absorbs nutrients. Digestion is completed in the intestine  **Frog** - a frog\'s tongue is attached to the front of the mouth so that it can capture flies. It has 2 sets of teeth to hold prey. When the frog swallows, it closes its eyes and pushes its eyes downward to cause pressure on the roof of the mouth, which forces the food to move into the gullet. Food passes the esophagus to the stomach and then to the intestines. Waste is expelled via the cloaca **Herbivores** - herbivores (e.g. cows, rabbits) need ways of breaking down and absorbing nutrients from plants. This is harder than breaking own meat: therefore, herbivores have longer, more coiled intestines than meat eaters e.g. humans. They also spend a lot of time chewing their food to break if down - the cow has 4 chambers to hold food during digestion. Cows have no cellulose-digesting enzymes; therefore, they rely on microorganisms to break down plant cellulose  - humans cannot digest cellulose, but it helps clean the intestines - rabbits: food passes the body half digested; therefore, they eat their own feces so the undigested nutrients in the feces can be fully digested **[The Respiratory System]** - function of the respiratory system is to obtain O~2~ and release CO~2~ **[Breathing]** see pg 70 Fig. 2.23 **[Circulatory System]** - the blood\'s transportation system including the heart, blood and blood vessels - the heart acts as a pump to transport and regulate the flow of blood through a series of blood vessels: arteries, veins, capillaries arteries -- thick-walled vessels that carry blood away from the heart to the tissues. They can withstand more force/pressure from blood due to thickness veins -- carry blood back to heart once O~2~ is gone to the lungs and gets more O~2~. They have less pressure since blood is further from the heart so they have thinner walls than arteries. Capillaries -- one cell thick and bring blood to extremities. O~2~ and CO~2~ flow in/out of capillaries via diffusion. Diffusion -- movement of a substance from an area of high to low concentration until a balance is reached. For example, if the blood has more O~2~ than the tissues, O~2~ will cross over the capillary wall to the tissue. If too much CO~2~ is in the tissues if diffuses out into the blood to get to the lungs so it can be exhaled. - Diffusion is how gas-exchange occurs in the alveoli of the lungs O~2~ in alveoli →bloodstream → body CO~2~ in bloodstream →alveoli → exhale **[The Excretory System]** - consists of kidneys, ureters, urinary bladder, urethra and skin - function is to filter waste products from the blood and maintain the proper levels of water and electrolytes in the body - as blood flows through kidneys, wastes (e.g. urea, CO~2~, water) are removed by filters called nephrons. These wastes form urine which moves out of the kidneys, down the ureters to the bladder where it is stored until expelled. Urine leaves the body via the urethra - the skin is considered to be part of the excretory system because it excretes water, salts and urea in sweat **[Plant Organ Systems (2 types)]** 1. Shoot System - Everything above ground: stem, leaves, buds, flowers and fruit 2. Root System - Everything underground (as well as aerial roots above ground) Transpiration -- evaporation of water through the stomata in the leaves **[Homeostasis]** Homeostasis -- maintaining a constant internal balance despite changes to the outside environment Your body is in homeostasis (a healthy balance) when: - Your blood pH is 7.35 - Your body temperature is 37°C - Your heart rate is about 72 beats/minute Your body maintains homeostasis by: - Evaporation of sweat from skin helps regulate body temp. - Kidneys maintain water balance - Blood distributes heat throughout the body - Hypothalamus regulates body temp. - Pancreas regulates blood sugar levels - Skeletal muscles contract and release heat **[How Organ Systems Work Together see pg. 80-81]** - Organ systems are interdependent because the action of one system contributes to the action of another system. For example, the circulatory system pumps blood, containing O~2~, throughout the body. The body cannot survive more than 6 minutes if the heart stops. However, the circulatory system to get the O~2~ so the blood can distribute it. **[Diagnosing Problems in Organ Systems]** **Circulatory System** - Your pulse tells you how often your heart beats in a minute. The average pulse ranges from 60-80 beats/min although factors (e.g. exercise) can alter it. - Normal blood pressure is systolic (pressure when heart contracts) and 80 diastolic (pressure when heart relaxes) - If the numbers are too high 135/85mm Hg there is too much blood pressure in the arteries - High blood pressure (called hypertension) can cause damage to the arteries, which can lead to heart attacks and heart failure - Blood tests can check levels of red and white blood cells, sugar levels, and hormone levels to indicate they are normal **[Excretory System]** Doctors check urine for: - If there are white blood cells in the urine, there is probably an infection in the excretory system - If too little urine is made it may be kidneys not working effectively to clean the blood of wastes - If too much urine is made or contains sugar it may be that the pancreas is not working properly and can be a sign of diabetes - Drugs (prescription, non-prescription and illegal) can be detected in the urine for a period of time **[Diagnostic Testing see pg. 94-99]** Medical imaging -- produces images of organs and tissues within the body for use in diagnosis and treatment. **X-Ray** - Most common form of medical imaging - High-energy radiation that can easily penetrate materials such as skin and tissues but not metals and bones; therefore, bones appear whiter than other structures - Can be used to check for cancer and to diagnose problems in the cardiovascular and respiratory systems, breasts, teeth etc... - Due to radiation, x-rays can cause changes and mutations to DNA - When a radiograph is taken the body part may be covered with a protective lead apron to minimize radiation absorption **Fluoroscopy** - Uses continuous beam of x-rays to produce images showing movement of organs e.g. stomach - The patient may need to ingest a contrast liquid e.g. barium or iodine to make the tissue visible Angiogram -- image of blood vessels Coronary angiogram -- special dye is injected into an artery in the groin so doctors can see blood flow and narrowing of arteries Cerebral angiogram -- shows blockages in blood vessels in the brain that can lead to a stroke **Radiotherapy** - A beam of x-rays is directed at a tumor so there is minimal damage to healthy normal cells **Ultrasound** - Uses high-frequency sound waves to produce images of body tissues and organs - Used to study soft tissues and major organs e.g. uterus. It is not recommended for studying bone since sound waves cannot penetrate the bone - Ultrasound is also used to guide biopsy and amniocentesis needles and to check on a growing fetus **Computed Tomography (CT or CAT Scan)** - Uses x-ray equipment to form a 3-D image from a series of images taken at different angles of the body - Used to diagnose cancer, abnormalities of the skeletal system and vascular diseases - Can be used to image bone, soft tissue and blood vessels at the same time **Magnetic Resonance Imaging (MRI)** - Uses powerful magnets and radio waves to produce detailed images of the body - Useful for imaging the structure and function of the brain, heart and liver, soft tissues and the inside of bones, forms of cancer, brain diseases and cardiovascular conditions **Nuclear Medicine** - Used to diagnose cancer, investigate blood circulation and evaluate disorders in organs - Uses radioisotopes (radioactive form of an element that emits radiation) which attaches to a chemical that is absorbed by a certain tissue or organ. As the radioisotope emits radiation, a special camera and computer detect the radiation and convert it into an image - Radioisotopes are also used to treat disease e.g. thyroid cancer uses radioactive iodine that kills cancer cells. After a few days the iodine decays to a non-radioactive element or is excreted by the body **Positron Emission Tomography (PET Scan)** - Used to detect cancer in tissues or to examine the effects of cancer treatments. It's also used to detect heart disease and some brain disorders e.g. Epilepsy and Alzheimer's disease **Biophotonics** - Uses interaction of light with cells and tissues to diagnose and treat abnormalities - Doctors are able to view tissues deep within the body using light e.g. endoscope to view digestive tract containing light and camera **[Decisions, Diagnosis and Treatment]** There are factors involved in making a diagnosis and in determining treatment: 1. the doctor ordering the most appropriate test 1. the patient understanding what the test is for and preparing for and following directions during the test properly 1. the technician administering the test properly 1. the radiologist properly reading and understanding the image 1. the administrators allocating adequate funding for technology **[Public Health Strategies see pg. 102-109]** **[Transplanting Organs]** See pg 114-118 In Canada, there are about 14 organ donors per 1 million people