Grade 11 Biology SBI3U1 Past Paper PDF

GENETICS! MENDEL - Gregor Mendel was a monk that studied mathematics. - He ran a hybridization experiment. - This involved cross-pollinating pea plants which could have have two possible physical traits for each plant, with no inbetween. - Pure bred plants are plants that...

GENETICS! MENDEL - Gregor Mendel was a monk that studied mathematics. - He ran a hybridization experiment. - This involved cross-pollinating pea plants which could have have two possible physical traits for each plant, with no inbetween. - Pure bred plants are plants that show the same trait to the parent from generation to generation. - To cross-pollinate, he moved the pollen from one plant to the pistol of another. - When the parents (P1) of the F1 generation reproduced (for example, white and purple plants), the F1 generation became all purple. - In the F2 generation when the F1 generation self-pollinated, it created a 3:1 ratio of purple to white flowers, and all of the lost forms of genes in the F1 generation came back in ¼ of the F2 generation. - This disproved the idea of blended inheritance and show that genes are actually discreet units that keep their separate identities when passed from generation to generation. ALLELES - Mendel reasoned that individual factors, or sets of genetic “information,” must control the inheritance of traits from peas, one from the male parent and one from the female parent. - The last conclusion Mendel made was that one factor in the pair can mask or hide the other. - In Mendel's experiments, tallness in pea plants masked the short pea characteristic. - Each pea plant inherits two alleles from its parents – one from the egg and one from the sperm. A pea plant may inherit two alleles for tall stems, two alleles for short stems, or one of each. - There are two types of alleles: - A dominant allele is one whose traits always shows up in the organism when it is present. These are always represented with a capital letter (e.g. TT, Tt). - A recessive allele is hidden by a dominant trait. It only shows up when it is alone. It is always represented by a lowercase version of the same letter of the dominant allele (e.g. tt). - When you have two genes that are different (not purebred) then you are called a hybrid. HYBRID CROSSES MONOHYBRID - Two or more alternate forms of a gene (segment of DNA that codes for a specific trait) are called alleles, which are located in the same position on a pair of homologous chromosome (e.g. flower color: purple, white). - The phenotype is the observable trait or characteristic. - The genotype is the pair of alleles in an organism. - A punnet square is a table in which all of the possible outcomes for a genetic cross between two individuals with known genotypes are given. - A homozygous pair of alleles is when they have the same alleles (e.g. RR, rr)​ - A heterozygous pair of alleles is when the plant has one of each alleles, and the dominant form is seen (e.g. Rr). DIHYBRID CROSS - A dihybrid cross examines the inheritance of 2 traits, which Mendel discovered would separate independently of each other during gamete production. - The parents in cross are heterozygous or hybrid for each trait. - 3:1:3:1 ratio. INCOMPLETE DOMINANCE - Incomplete dominance occurs when neither gene is expressed completely dominant over the other. - With some traits, a cross between pure contrasting forms of the trait results in a hybrid of heterozygote that shows an “in-between” or intermediate form. - The phenotype is part way between the phenotypes of the two different homozygous genotypes. CO-DOMINANCE - Two alleles are expressed at the same time; neither allele dominates the expression of the other in the resulting heterozygote. - Example includes red and white petals, something that occurs if a purebred red and white flower pollinate. BLOOD TYPES - Humans have 4 different blood types: A, B, AB, and O. - A and B alleles are dominant over O.  - A and B are codominant to each other. - O is recessive. - A glycoprotein are special markers on the membrane of all blood types except for type O. - It acts as an antigen for type O’s and allows the body to initiate immune responses. It is also necessary for blood coagulation. - Type AB can take blood from all due to having both A and B glycoprotein, and type O can give blood to all blood types due to having no glycoprotein. However, type AB can only give to type AB and type O can only receive from type O. PHENOTYPE (BLOOD TYPE) POSSIBLE GENOTYPES A IAIA B IBIB AB IAIB O ii - The RH factors (+/-) is passed down. + means that you have the genetic RH factor, and - meaning that you don’t have the RH factor. SEX LINKED TRAITS - Sex linked traits are controlled by genes located on the sex chromosomes. - If a gene is located in section A, B, or C on the X chromosome, then a female would have 2 alleles for that trait, and a male would have 1 allele for that. - For example, color blindness is a sex-linked trait. - Let N represent the allele for normal color vision, and n represent the allele for color blindness. - You must use X and Y in the genotype of sex-linked conditions. FEMALE MALE NORMAL: XNXN NORMAL: XNY CARRIER: XNXn COLOR BLIND: XnY COLOR BLIND: XnXn - Genes that are on the same chromosome are said to be linked genes. - X-Linked dominant diseases comes from affected fathers and goes into affected daughters. - X-Linked recessive diseases comes from affected mothers and goes into affected sons. MORGAN’S EXPERIMENT - In Morgan’s experiment, she used a fruit fly to study.  - This was because fruit flies reproduce rapidly, as offsprings are capable of mating shortly after leaving the egg, and females produce over 100 eggs after each mating. - As well as this, males are easily distinguished from females. - Morgan noted the appearance of a white eyed male among many red eyes offsprings, to which she concluded the white eyed trait is a mutation. - A mutation is a heritable change in the molecular structure of DNA, which can change the appearance of the organism. - She then mated the white eyed male and the red eyes female together, which resulted in all of the F1 generation to have red eyes. She then mated two hybrids from the F1 generation, which produced 75% red eyed and 25% white eyed. This was then noticed that only the males had white eyes, and 50% of the men had white eyes and 50% of them had white eyes. - She then determined that the Y chromosome does not carry the gene to determine eye color, to which the term sex-linked traits was discovered, which are traits located on the sex chromosomes. - The genotypes F1 generation were later found out to be XRXr for the females, and XRY for the males. GENETICALLY INHERITED DISORDERS CYSTIC FIBROSIS - Cystic fibrosis is a genetic condition/mutation in the autosomal chromosomes that affects a protein in the body. People who have cystic fibrosis have a faulty protein that affects the body's cells, its tissues, and the glands that make mucus and sweat. - This causes mucus to accumulate in the lungs and create problems with digestion. - This disorder is autosomal recessive. PHENYLKETONURIA (P.K.U.) - Phenylketonuria is a rare inherited disorder that affects how the body breaks down a substance called phenylalanine, an amino acid, which is found in many foods. - People with P.K.U. can't process this substance properly, so it builds up in their body. - If untreated, too much phenylalanine can cause brain damage and intellectual disabilities. - This is an autosomal recessive disease and could be a mutation in the gene that makes these enzymes to process the amino acid. BREAST CANCER - Breast cancer happens when abnormal cells in the breast grow and divide uncontrollably, forming a tumor. - These are caused mutations in the BRCA1 and BRCA2 genes are inherited in an autosomal dominant pattern. - BRCA stands for BReast CAncer. The numbers determine which gene it is (in this case, gene 1 and 2). HUNTINGTON’S DISEASE - Huntington’s Disease is an autosomal dominant inherited disease (can also be mutation in the gene) that is degenerates brain tissue (neurodegenerative). - Symptoms usually appear around 30-40s, usually after reproductive years. HEMOPHILIA - Hemophilia is a X-Linked recessive inherited disorder which causes a person affected with hemophilia’s blood to not clot properly, which is something needed to stop bleeding. - This means that very simple things like a cut can be more serious to someone with hemophilia as the cut won’t stop bleeding as fast as a normal person. - This occurs mostly in males. RED-GREEN COLOR BLINDNESS - Red-Green Color Blindness is a X-Linked recessive inherited disorder which causes a person to have difficulty distinguishing red and green from other colors. - This occurs mostly in males. EVOLUTION! ORIGIN OF LIFE VIEWS - There were 4 main views on the origin of life: special creation, theistic evolution, panspermia, and spontaneous generation by chemosynthesis. - Special creation is the idea that a greater being or force created all of earth. It was the oldest idea of where everything came from. While many religions believed in this, it lacked scientific backing and the idea of evolution. - Theistic evolution is the idea that there is a greater force controlling evolution (e.g. spontaneous generation, the idea that living organisms could arise from nonliving matter). This idea had no scientific backing but does not conflict with science or religion.  - Panspermia is the idea that life came to earth from somewhere else, like am asteroid or meteor. This idea has not been proven or tested due to lack of technology to do so, but may be revisited in the future. - Spontaneous generation by chemosynthesis is the idea that the spontaneous generation of organic molecules (C.H.O.N) evolved into early cells.** DEVELOPING THEORY OF EVOLUTION - The most predominant view of the origins of life is the religious beliefs of direct actions of a creator who formed the entire universe, species were created in a single week and remained unchanged over the course of time, and the earth is only a few thousand years old. JEAN-BAPTISTE LAMARCK - He compared the current species of animals with fossil forms, and observed a ‘line of descent’ where the fossil record showed a series of fossils (from older to more recent) that led to a modern species. - He introduced the theory of inheritance of acquired characteristics, which states that organisms become progressively adapted to their environments and that species were initially primitive and soon increased complexity over time until they achieved perfection. - Lamarck also theorized characteristics acquired during an organism’s lifetime could be passed on to its offspring (e.g. giraffe’s effort to reach for food would lead to longer necks that could be passed on to the next generation). - This idea in the evolution of species then influenced Darwin's theory. CHARLES DARWIN - Darwin's name is associated with evolution because he was able to link all prevailing knowledge from others with his own observation. - He went on the HMS Beagle in 1831 as a naturalist, which was a 5 year voyage that took him around the world. - When he was in the galapagos islands, he saw a lot of the same animals but were distinctly different from island to island. - He then concluded that they must have modified from an ancestral form of the an animal that was blown by chance into the newly formed galapagos islands. APPROACH TO EVOLUTION 1.​ Earth is very old, and organisms have been changing steadily throughout the history of life. 2.​ All organisms are descendants of a common ancestor (early life forms).  3.​ The great diversity of life found on earth is the result of new species forming from older species. 4.​ Evolution proceeds via gradual changes in populations, not by the sudden production of individuals of dramatically different types 5.​ The major agent of evolutionary change is natural selection. NATURAL SELECTION - In natural selection, there is usually a variation among individuals (e.g. giraffes with short and long necks). - The giraffes with the long necks can survive to get food better compared to the short neck ones. - Due to selective pressure (the evolutionary force that causes a particular phenotype to be more favorable in certain environmental conditions), the individuals with the better traits are adapted to survive and pass down their genes to their offsprings, while the individuals with unfavourable traits are less likely to adapt and to pass down their genes. DARWIN VS LAMARCK - Lamarck believes that they will grow into favorable traits, while Darwin believes that favorable traits are passed down. ARTIFICIAL SELECTION VS NATURAL SELECTION - Artificial selection is when humans select for desirable traits in plants and animals, and then take steps to ensure those traits are passed on to future generations. - Natural selection is when the environment determines what traits are more likely to be passed down/survive. - Artificial selection requires human input, while natural selection does not. MECHANISMS OF EVOLUTION CHANGING ALLELE FREQUENCIES - While organisms do not choose their genes, gene frequency of a species changes over time. The 5 mechanisms by which this happens are: mutation, gene flow, non-random mating, natural selection, and genetic drift. MUTATION - Random changes in DNA occur due to radiation, viruses, or just chance. GENE FLOW - Migration may cause one population of organisms to breed with another. - This could change (increase or decrease) the allele frequency of both populations. NON-RANDOM MATING - This causes certain alleles to increase in frequency and others to decrease. - Often, the increasing alleles are the ones that the opposite sex finds attractive. GENETIC DRIFT - This is the random change in allele frequency caused by chance. This occurs more often in small populations (e.g. refer to Founder and Bottleneck effects) NATURAL SELECTION - Environmental conditions favour certain traits that get passed to offspring. This will change allele frequency in a population. - These selective pressures can result in different patterns of natural selection: - Directional, stabilizing, disruptive, and sexual (refer to next part). PATTERNS OF NATURAL SELECTION STABILIZING SELECTION - Natural selection that favours intermediate phenotypes (e.g. on cheetahs, short tails mess up balance while long tails will drag on the ground, making medium tails more favorable). - Extremes of most traits can be unattractive and unhealthy. - Stabilizing selection reduces genetic variation. DIRECTIONAL SELECTION - Favours the phenotypes at one extreme. - This causes a trait to move in one direction. - This was evident in England in the 1800s when darker moths were more likely to survive. It has also happened to the head size of humans where bigger heads (which can hold bigger brains) give them an advantage. DISRUPTIVE SELECTION - Favours two or more variations of a trait that different from the current population average. - These are often variations at opposite extremes (e.g. short tails on squirrels help keep predators from catching them on the ground, while long tails are good for balance in the trees. Medium tails don’t help, making these two opposite extremes favorable phenotypes). SEXUAL SELECTION - Usually based on competition between males and decisions made by females (e.g. of non-random mating). - Traits like colour of feathers, size and strength may drive this type of selection in most species. - This results in sexual dimorphism, how two sexes of species differ in external appearance (e.g. peacocks with large and flashy feathers, while peahens do not). GENETIC DRIFT THE FOUNDER EFFECT - If a small number of individuals get separated from the rest of their population, they may survive to form a new species. - There is a chance that these organisms have some genes that are rare among the general population. - These genes will then be more frequent in the new population and may cause them to be different from the general population of their species. BOTTLENECK EFFECT - Sometimes, changes in gene distribution are the result of a rapid decrease in population size. - A particular gene may have allowed some of the organisms to survive and pass on the gene THE HARDY-WEINBERG PRINCIPLE - A mathematical equation to explain the relationships between allele frequencies within a population and the chances of those frequencies remaining constant. - In large populations in which only random chance is at work, allele frequencies are expected to remain constant from generation to generation. - Factors that causes allele frequencies to change can lead to evolution; these five conditions: - Natural selection, which is the favouring of passing on of some alleles over others. - Small population size, which is the increasing likelihood of genetic drift. - Mutation, which introduces new alleles to a population - Immigration or emigration, which introduces/removes alleles in a population - Horizontal gene transfer, which is the gaining of new alleles from a different species (non-sexual movement) EVIDENCE FOR EVOLUTION PALEONTOLOGY (FOSSILS) - Fossils form when organisms become buried and compressed in sediment and are eventually converted into rock. - The fossil record is the sequence of layers of sediment from the earliest life to present day. - This provides a history of life on Earth (e.g. the kinds of living things alive in the past). - Fossil records support the idea of evolution by 1. Fossils from more recent geological periods are much more similar to species alive today. 2. Fossils appear in chronological order (older at the lower strata). 3. Organisms do not appear simultaneously (e.g. fish are the oldest vertebrates, amphibians, reptiles…) 4. Changes are slow, as these changes can take millions of years, so the fossil records give a snapshot of ancestral forms. 5. Transitional fossils are significant in showing an intermediary link between two groups of organisms. - Transitional fossils are a fossil or species intermediate in form between two other species in a direct line of descent (e.g. archaeopteryx are one the earliest birds, and had both traits of birds and reptiles, which proved that birds evolved from dinosaurs). GEOGRAPHICAL DISTRIBUTION OF SPECIES - Biogeography is the scientific study of the geographic distribution of organisms based on both living species and fossils. - Geographically close environments are more likely to be populated by species that are related than are locations that are geographically separated but environmentally similar. - (e.g. a desert and a forest of South America have species more closely related compared to a desert in Africa and a desert in Australia). - The biogeography of islands yields some of the best evidence for evolution. - (e.g. the many marsupials but few placental animals found in Australia suggests that the marsupials evolved in isolation from places where ancestors of placental mammals lived). - There are two ways island forms: - Volcanic origin (e.g. Galapagos islands and Canary islands), where animal species arrive by flying or floating from the nearest main land. - Non-volcanic origin (e.g. New Zealand and Madagascar) are broken off adjacent continental land masses, which are populated by species that lived on the land before separation. - Remote islands allow for isolation, possible adaptive radiation and animals with unique behaviours (e.g. Galapagos tortoises live on remote islands and show no fear of humans) ANATOMY HOMOLOGOUS FEATURES - A structure with a common evolutionary origin that may serve different functions in modern species. - Structures of different species that have the same number and arrangement of bones, muscles, ligaments, tendons & blood vessels, but have different functions, making them homologous. - For example, pentadactyl limbs (5-fingered limbs) found in different animals provide strong evidence for evolution among vertebrates like humans, whales, and bats). - This helps provide evidence for different organisms descending from a common ancestry & divergent evolution. ANALOGOUS FEATURES - A structure that performs the same function as another but is not similar in origin or anatomical structure  - For example, bird wings and bat wings. - No common evolutionary origin, but provides evidence for natural selection and convergent evolution. VESTIGIAL FEATURES - A structure that is rudimentary and non-functioning, or only marginally functioning. - It is homologous to a fully functioning structure in a closely related species. - For example, the appendix in humans and the pelvic bone in whales. EMBRYOLOGY - Embryology is the study of embryos, or the study of early stages of development. - All vertebrate embryos have gill pouches and tails, which points to a common ancestral origin. - Related species would share both adult features and embryonic features. BIOCHEMISTRY DNA EVIDENCE - If two species have similar patterns in their DNA, this indicates that the sequences must have been inherited from a common ancestor. - For example, gene sequencing have shown that dogs and bears are related. - The greater the similarity in DNA sequences, the more closely related the organisms are. - For example, human and chimps have ~2% difference, while humans and lemurs have 45% difference. PROTEIN EVIDENCE - Much of the amino acid sequence is the same in all living organisms with 102-112 amino acids in total. - For example, chimp to rhesus monkey only have 1 a.a. difference. - Cytochrome C is the protein for all living cells for cellular respiration. SPECIATION ZYGOTIC MECHANISMS - A species is a group of organisms that can mate with each other and produce fertile offspring - In order for a new species to be created, reproductive isolation must occur. - Members of a species must, for some reason, become unable to reproduce with the rest of the species. - There are two reasons why two organisms may be unable to produce fertile offspring: prezygotic isolation and postzygotic isolation. PREZYGOTIC ISOLATION - Prezygotic isolation is the inability of two organisms to create a fertilized egg. - There are five main types of prezygotic evolution: Temporal Occurs when two species Frogs live in the same pond but mate at different times of breed in different seasons. the year. Ecological Occurs when two species Lions and tigers can potentially occupy different habitats. interbreed, but usually occult different habitats. Behavioural Occurs when two species have Certain groups of birds will only different courtship respond to species-specific behaviours. mating calls. Mechanical Occurs when physical Certain breeds of dogs are differences prevent morphologically incapable of copulation/pollination. mating due to size. Gametic Isolation Male gametes may come into Sea cucumbers and sea urchins contact with female gametes release sperm and eggs into open but may not recognize an egg water. The sperm recognize only of a different species. their own species through chemical markers. ALLOPATRIC SPECIATION - Organisms can be isolated by a geographical barrier (e.g. a body of water). - In time, they will become different than the other members of the species and become unable to reproduce with them. SYMPATRIC SPECIATION - Organisms can also stay in the same geographical area and become isolated until they form a new species. POSTZYGOTIC ISOLATION - Postzygotic isolation is when organisms can produce a zygote but the zygote cannot develop into a fertile adult. - There are 3 types of postzygotic isolation. Hybrid Inviability Hybrids are produced but fail Certain types of frogs form  to develop to reproductive hybrid tadpoles that die before maturity. they can become a frog. Hybrid Infertility Hybrids fail to produce Mules are sterile hybrids results function gametes (sterility). from mating between a horse and a donkey. Zygote Mortality Mating and fertilization are Some species of sheep and goat possible, but genetic are able to mate, but the zygote is differences result in a zygote not viable. unable to develop properly. HUMAN INFLUENCE - Human activities, such as agricultural expansion and the construction of roads, cause once large habitats to be fragmented into smaller areas that isolate populations. - These barriers reduce gene flow and biodiversity amongst a species making them at greater risk of disease and changing environmental conditions, e.g. climate change. PATTERNS OF EVOLUTION DIVERGENT EVOLUTION - A pattern of evolution where species that were once very similar (common ancestry), become increasingly different over time (homologous traits). - This is because natural selection has favoured the evolution of different species that adapt to different environments, to which each species fill different ecological niches. ADAPTIVE RADIATION - A single species can, over time, develop into a number of separate species that are well suit to their own, distinct habitats. - For example, finches have a common ancestry that soon evolved in isolation (different habitats) to make 15 different species. CONVERGENT EVOLUTION - Certain traits will give an organism an advantage in a given habitat.  - Over time, different species (no common ancestry) will develop these traits independently and become more alike (analogous traits). - For example, bats and birds have wings but they do not share a common ancestor. COEVOLUTION - Coevolution is the in which one species evolves in response to the evolution of another species. - Their evolutionary success is closed linked to each other as they create a symbiotic relationship. - For example, the Madagascar long-spurred (30 cm) orchid is pollinated by a hawk moth whose tongue is 30 cm long. DIGESTIVE SYSTEM! THE DIGESTIVE SYSTEM ORGAN FUNCTIONS - parotid gland produces saliva to help break down food. - oral cavity is where food is chewed and mixed with saliva for digestion. - sublingual gland produces saliva to lubricate and begin food digestion. - esophagus transports food from the mouth to the stomach. - stomach breaks down food with stomach acids and enzymes created by gastric liquid (mostly mucus, has some enzymes and HCl). - liver produces bile to help digest fats and detoxifies harmful substances. - pancreas produces digestive enzymes and hormones. - pancreatic duct transports pancreatic enzymes to the small intestine. - gallbladder stores and concentrates bile, releasing it into the small intestine. - cystic duct carries bile from the gallbladder to the common bile duct. - common bile duct delivers bile from the liver and gallbladder to the duodenum. - duodenum is the first part of the small intestine, where bile and most of the digestive enzymes break down food. - jejunum is the second part and helps digest and absorbs some nutrients from digested food. - ileum is the last part that absorbs most of the nutrients from digested food. - large intestine (ascending, transversal, descending colon) absorbs water and remaining nutrients to whilst forming solid waste. - caecum connects the small intestine to the large intestine and absorbs fluids. - rectum stores feces. - anus is the opening through which feces are passed out from the body. DIGESTIVE SPHINCTERS - cardiac sphincter prevents stomach acid from backing up into the esophagus. - pyloric sphincter controls the release of food from the stomach to the small intestine. - ileocecal sphincter regulates the flow of digested material from the small intestine to the large intestine. - anal sphincter controls the release of feces from the rectum. MOVEMENT IN THE GI TRACT MUSCLE TYPES - Skeletal muscles, which are the muscles we consciously control (e.g. biceps, triceps, etc). - Smooth muscles, which are found in internal organs and in the ones involved in digestion. We do not consciously control these muscles (e.g. esophagus, uterus, etc). - Cardiac muscles, which are found only in the heart to contract automatically. 1. TEETH - The mouth is the initial site of physical digestion of food and chemical digestion of carbohydrates. - Teeth in the mouth help break down food into smaller pieces and help to increase surface area available for chemical digestion. - There are different teeth for different functions: - Incisors, the top of your teeth that is used to cut food into smaller pieces. - Canines and bicuspids, which are in between your molars and incisors, used to pierce and tear. - Molars, the sides of your teeth that are used to crush and grind food. 2. SALIVARY GLANDS - There are 3 pairs of salivary glands (parotid glands, the submandibular glands, and the sublingual glands) in the mouth that produce saliva and release it through ducts in the mouth. - Saliva is made up of 99% water to help moisten and soften up food, while the other 1% is salivary amylase, which is used to chemically digest complex carbohydrates into smaller molecules. 3. TONGUE - The tongue helps with: - To positioning food for swallowing/placing food to appropriate teeth. - Mixing food with saliva. - Rolling food into a ball of food (bolus). - The bumps on our tongue are papillae that contain taste buds to send messages to the brain about how something tastes (e.g. sweet, sour, bitter, etc). 4. MOUTH - The mouth is made up of three main structures: - The hard palate, which is the bony part behind the teeth (top of mouth). - The soft palate, which is the non-bony part (near the uvula). - Uvula, the fleshy flap of tissue. It is an extension of the soft palate. - These structures help with preventing food from passing into the trachea (windpipe). 5. PHARYNX - Both food and air pass through the pharynx. - The pharynx helps moves the bolus to the epiglottis to the esophagus. 6. EPIGLOTTIS - The epiglottis is the flap of cartilage at the base of the tongue to cover the entrance to the trachea when you swallow. - This helps provent food from entering the windpipe. 7. ESOPHAGUS - It is a ~25 cm long muscular, collapsible tube that lies flat until food enters it. - It is made up of smooth muscle, and no chemical digestion happens in the esophagus. - Peristalsis happens in the esophagus, which is a series/waves of coordinated muscle contraction that move food along the gastrointestinal tract. - Smooth muscle in the GI tract contract in response to being stretched by the food, so it is independent of gravity (can eat upside down). - The main force of pushing bolus from the esophagus into the stomach. - There ar specialized epithelial cells that line the esophagus to protect it from wear and tear when food moves down it. - Sphincters are thick rings of circular, smooth involuntary muscle that constrict to close off body passages. They relax to allow the movement of substances into or out of a body tube, as well as prevent reverse peristalsis. (REFER TO DIGESTIVE SPHINCTERS) - The sphincter from the esophagus to the stomach is the cardiac sphincter. 8. STOMACH - The stomach is stretchable, and is made up of 3 layers of smooth muscle. - These muscle layers contract to squeeze and mix food with gastric juices (peristalsis). - Reservoir for food and releases contents into small intestine in intervals. - Rugae are thick folds in the inner wall of the stomach that allow the stomach to expand and contract in relation to the volume of food in the stomach. - When the walls of the stomach contract, there is physical digestion of food as it is mixed with the gastric juices. - Gastric juices contain pepsinogen (inactive form of pepsin), mucus, HCl(aq), and water. - HCl has many functions in the stomach: - Activating pepsinogen to pepsin. This helps attack peptide bonds in proteins to break them into smaller peptide chains. - Maintaining a low pH to allow pepsin to work. - Killing microbes. - Changing the shape of proteins to be easily digested by enzymes. - HCl also helps with increasing surface area of the food to expose food surfaces to more digestive enzymes. - Mucus helps with protecting the stomach lining from being digested from pepsin and damage from HCl). - If the mucus lining breaks down/cells are exposed to the acidic gastric juices in the stomach, an ulcer may result or cause inflammation in the lining. - After this digestion, the ‘food’ is now chyme, a mixture of partially digested food, water, and gastric juices. - Chyme helps with increasing the surface area of food by breaking it down into smaller components, and stimulates digestive glands (e.g. gallbladder and pancreas) to secrete their respective solutions (e.g. bile, digestive enzymes, etc.) - The chyme enters the duodenum by the pyloric sphincter, which controls the movement of chyme out of the stomach and into the duodenum to release the chyme in intervals. 9. SMALL INTESTINE - The function of the small intestines is to digest (physically and chemically) and absorb nutrients. - Carbohydrates digest further into monosaccharides. - Proteins are further digested from peptide chains, to dipeptides, to amino acids. - Lipid digestion begins, where physically, fats turn into small fat droplets, and chemically they turn from triglycerides to 3 fatty acids + glycerol. - The small intestine allows for thorough digestion due to its length (6.5m-9m), and allows for adequate nutrient absorption. - The surface area in the small intestines are increased by its long tube, folds in the inner lining of the tube, villi on the folds of the inner lining, and the microvilli on the surface of the cells lining the villi. - There are three parts of the small intestine (REFER TO DIGESTIVE ORGANS FOR FUNCTIONS): 1. Duodenum 2. Jejunum 3. Ileum - 80-90% of nutrient absorption takes in the last two parts (jejunum and ileum) after digestion. - The small intestinal juices contain proteases and amylases and other essential substances, such as water. - There are three accessory organs to secrete substances into the small intestines (REFER TO DIGESTIVE ORGANS AND CHEMICAL DIGESTION): 1. Liver 2. Pancreas 3. Gallbladder - The ileocaecal valve is an anatomical landmark separating the ileum (small intestine) from the large intestines (colon). It is a one-way valve. VILLI/MICROVILLI - Villi is used to increase the surface area of the small intestine to absorb more nutrients. - The epithelial cells that make up the villi has even smaller, microscopic projections of the cell membrane called microvilli. - Within each villus is a network of tiny blood vessels called capillaries. - Capillaries are part of the circulatory system. All nutrients, except digested fats, enter the bloodstream through the capillaries. - Digested fats are then transported through small vessels called lacteals (a lymphatic vessel within a villus, through which digested fats enter the circulatory system). - The digested fats are transported into the lymphatic system, and from there into the bloodstream. 10. LARGE INTESTINE - The appendix is a finger-like pouch in the large intestine, just after this ileocaecal valve. It plays no role in digestion, but has been shown to have immune function. - No digestion occurs in the large intestine. - There are three major sections of the large intestine:  1.​ Ascending colon 2.​ Transversal colon 3.​ Descending colon - The main functions of the large intestines are: - Reabsorption of water back into the blood stream ​ - Helps with bacteria absorb vitamins, water (to prevent dehydration) and some minerals. - Stores wastes before elimination (poop). - The large intestines makes sure we get all the vitamins and minerals needed to maintain health. - Solid waste/feces/stool is moved along the large intestine by peristaltic muscle contractions toward the rectum and through the anus. - Mucus and dietary fibre helps speed the removal. - The colour is generally influenced by what you eat as well as by the amount of bile in your stool. - As bile pigments travel through your gastrointestinal tract, they are chemically altered by enzymes, changing the pigments from green to brown CHEMICAL DIGESTION, THE ACCESSORY GLANDS, AND ABSORPTION - A catalyst is a substance that helps speed up the process if a chemical reaction without being used up or changed by the reaction. - An enzyme is a protein molecule that acts as a catalyst in a chemical reaction within a biological process. - A substrate is a molecule being acted upon by an enzyme during a chemical reaction. MACRONUTRIENTS GENERAL NAME OF PRODUCTS (SUBSTRATES) ENZYME Proteins Proteases (e.g. pepsin) Amino acids Fats Lipases (e.g. pancreatic Fatty acids/glycerol lipase) Carbohydrates Carbohydrases (e.g. salivary Monosaccharides amylase) - Bile is an emulsifier that produces bile salts to release them into the gall bladder for storage until needed. - Bile salts emulsify large fat droplets into smaller ones - Bile salts are needed to break down fat because lipases can act on small droplets of fat more rapidly than a larger one. - It also helps increase the surface area for exposure of substrate molecules. ACCESSORY GLANDS GALL BLADDER - The gall bladder stores needed bile salts. - The bile are secreted into the duodenum via the cystic duct to the common bile duct (common to liver, gall bladder, and pancreas) PANCREAS - A large gland located just beneath the stomach that produces necessary enzymes & secretions. These substances are released into the duodenum. - The contents of the pancreatic juices include: sodium bicarbonate, amylases, lipases, proteases (not pepsin), nucleases, and water. - Bicarbonates are important because they are alkaline and can neutralize the acidic chyme entering duodenum from the stomach. - Pepsin is not in the pancreatic juice as it would become inactive due to the high pH. - Similar to stomach enzymes, if they were active they would digest the protein in the intestinal lining. - The slightly basic pH (>7 →9) activates proteases to break proteins into simpler peptides. LIVER - The liver has many functions: - Helps break down old red blood cells and hemoglobin. - Recycles old hemoglobin to make bile salts. - Collects from the bloodstream chemicals in excess; stores vitamins A, B2 & D. - Detoxifies various poisonous chemicals (e.g. drugs, alcohol, etc). - Converts some amino acids to fat, and monosaccharides to glycogen for storage (may also reverse to maintain glucose levels) ABSORPTION - The small intestine helps turn proteases → simple peptides → dipeptides → amino acids, as well as carbohydrases → disaccharides → monosaccharides. - Nucleic acids (RNA & DNA) are also digested into nucleotides with the help of pancreatic enzyme (nuclease).​ - Lactase is a carbohydrase that helps in the breakdown of lactose into glucose & galactose. - Lactose intolerance occurs when the body doesn't produce enough of the lactase enzyme, which is needed to digest lactose. - Within the folds of the small intestines are the absorptive “organs” called villus or villi (REFER TO MOVEMENT IN THE GI TRACT). - Carbohydrates and amino acids are absorbed across the membrane of the microvilli and then secreted into the blood capillaries. - Passive transport is the movement of materials across a cell membrane without the use of energy from the cell. This includes (simple) diffusion, osmosis, and facilitated diffusion. - Active transport is the transportation of materials through a cell membrane using energy from the cell. CHEMICAL DIGESTION DIGESTION OF CARBOHYDRATES DIGESTION OF PROTEINS DIGESTION OF FATS STRUCTURE OF VILLI - Things like protein, carbohydrates, fats and all of its simpler form cannot enter the villi. - Things like amino acids, monosaccharides, minerals, vitamines (e.g. B, C), water, glycerol, fatty acids, and vitamins (e.g. A, D, E) can go in the villi. - Amino acids, monosaccharides, minerals, vitamines (e.g. B, C) and water are all water soluble. - Glycerol, fatty acids, and vitamins (e.g. A, D, E) are all fat soluble. DISORDERS OF THE DIGESTIVE SYSTEM DISORDERS + WHAT IS IT + CAUSES PREVENTION OR ORGANS SYMPTOMS TREATMENT INVOLVED Nausea, vomiting, - It’s in the name… - The brain has signals that - Fiber intake, physical something is wrong in the activity, monitor diet, diarrhea. GI tract (infections, medication.  irritation, and more), causing nausea and maybe vomiting to remove toxins or foreign substances from the body. - Diarrhea can happen with increased fluid in intestines, infections from viruses, damaged intestinal lining that cannot absorb the water from the waste, and more. Ulcers - A sore in the digestive - The stomach or small - Medication system (mouth, stomach, intestine lining is damaged - Lifestyle changes (e.g. etc). by stomach acid or other avoid smoking and alcohol) - Symptoms include: nausea, digestive juices. - Surgery pain, vomiting. Some may not experience symptoms. Gall Stones (affects - Hardened deposits of Has many possibilities: - Laser procedure to digestive juices (bile) in - Bile is too high in crumble stones to smaller gallbladder) your gall bladder. cholesterol pieces to be passed out of - Symptoms include: nausea, - Bile too high in bilirubin, a the body. vomiting, fever, chills, pain chemical that breaks down - Surgery to remove the gall in the right shoulder, pain in red blood cells bladder. upper abdomen. - Gall bladder not emptying fully/properly Acid Reflux / - Acid from the stomach - The esophageal sphincter - Avoid foods that loosen causes a burning sensation (cardiac) doesn’t close the cardiac sphincter. This Gastroesophageal in the middle of the chest properly and stomach acid includes foods like Reflux Disease (near the heart). bubbles up into the chocolate, caffeine, alcohol esophagus. and fatty foods (G.E.R.D.) - Antacids such as Tums or Pepto Bismol provide short term relief by neutralizing the acid CIRCULATORY SYSTEM! GENERAL INFORMATION - The main functions of the circulatory system include: 1.​ To deliver oxygen from the respiratory system. 2.​ To deliver nutrients from the digestive system. 3.​ To deliver hormones from the endocrine system. 4.​ To deliver chemicals/cells from the immune system. 5.​ To deliver metabolic wastes to the lungs and kidneys. 6.​ To distribute thermal energy throughout the body to maintain body temperature in warm-blooded animals. 7.​ To transport waste products out of the cells. - Cells are close to blood vessels to allow them to take up nutrients from the blood and to exchange waste products into the blood to be removed. - There are three types of blood vessels: 1.​ Veins 2.​ Arteries 3.​ Capillaries - Cellular respiration is the chemical reaction that requires the presence of oxygen in the mitochondria. - The three components of all circulatory systems include: 1.​ A fluid that transports/circulates material throughout the body. 2.​ A network of tubes in which the fluid circulates. 3.​ A pump that pushes the fluid through the tubes. - The two-circuit circulatory system is made up of the pulmonary circuit and the systemic circuit. - The pulmonary circuit circulates blood to the lungs for gas exchange with the external environment. - The systemic circuit circulates blood around the body to deliver oxygen, nutrients, and other substances to the body cells, and to pick up carbon dioxide THE HEART AND BLOOD PRESSURE HEART ANATOMY ​ 1. Superior (1) and inferior vena cava (2) carries blood from the body to bring deoxygenated blood into the heart​ 2. This blood enters the right atrium (3).​ 3. The blood flows through the tricuspid valve (4) to the right ventricle (5). ​ 4. The right ventricle (5) contracts to push blood through the semilunar valve (6).​ 5. The blood then travels from semilunar valve (6) to the pulmonary artery (7), which carries the blood to the lungs for oxygenation. ​ 6. After the blood is oxygenated, it returns through the heart through the pulmonary veins (8). 7. The oxygenated blood enters the left atrium (9). 8. Blood moves from left atrium (9) to the bicuspid valve (10) into the left ventricle (11). 9. The left ventricle (11) contracts to push the oxygenated blood through another semilunar valve (12). 10. The blood is then pumped into the aorta (13), which is a large artery that distributes oxygenated blood to the rest of the body - The septum (14) is the wall that separates the left and right sides of the heart to ensure that oxygenated and deoxygenated blood don't mix. - The walls of the atria are thinner than the walls of the ventricles as the atria are receiving chambers and do not have to pump blood with any force to get the blood through the ventricles. - The blood on the right side is low in oxygen because the right side pumps blood to the lungs for oxygen. - The blood on the left side of the heart is high in oxygen because the left side pumps blood with oxygen to all parts of the body. - The heart muscle gets its nutrient supply from the coronary blood vessels. - Angina (aka angina pectoris) is chest pain that occurs when the heart muscle is not getting enough oxygen. - Symptoms include feeling heaviness, pressure, squeezing, tightnice, or pain in the chest and is a symptom of coronary artery disease (REFER TO CARDIOVASCULAR DISEASE)**. BLOOD PRESSURE - Blood pressure is the force of the blood on the walls of the arteries. - Blood pressure is maintained by the elastic connective tissue and smooth muscle tissue (e.g. the artery walls, which stretch to accommodate increased fluid, but also recoil to help push along blood). - Systolic blood pressure is the pressure exerted by blood on the arteries when your ventricles contract (aka ventricular contraction). - Diastolic blood pressure is the pressure exerted by blood on the arteries during ventricular relaxation or filling. - Blood pressure can be measured by using a sphygmomanometer. - A normal blood pressure reading would be 120 mmHg for systolic blood pressure, and 80 mmHg for diastolic blood pressure. - Stroke volume is the volume of blood pumped during each cardiac cycle or heart beat. - At rest stroke volume is ~70 mL. - When the heart beats forcefully, such as during exercise, the stroke volume can be nearly 200 mL. FACTORS ADJUSTING BLOOD PRESSURE - Blood pressure can be adjusted by changing as well as regulated by mechanisms that control: 1.​ Cardiac output. 2.​ Arteriolar resistance. - Cardiac output is the amount of blood pumped from the heart each minute. - The formula for cardiac output is heart rate * stroke volume = cardiac output. - During rest, C.O = 72 beats/min * 70 mL/beat  = 5040 mL/min = ~ 5 L/min - Cardiac output can be changed by changing stroke volume, heart rate or both. - Arteriolar resistance refers to how much arterioles resist the blood flow by narrowing the diameter of the vessels. - This means that there are lower blood flow to the capillaries and higher blood flow in the arteries, leading blood pressure to go up. - Arteriolar dilation refers to the widening of the arteriole by increasing the diameter of the blood vessel. - This means that there are higher blood flow to the capillaries and lower blood flow in the arteries, leading blood pressure to go down. - The cardiac centre in the brain (medulla oblongata) can increase or decrease cardiac output by increasing or decreasing heart rate through the sino-artial node (also known as the SA node). - The SA node generates an electrical signal that causes the upper heart chambers (atria) to contract (REFER TO CARDIAC CYCLE AND HEART SOUNDS)** FACTORS AFFECTING BLOOD PRESSURE 1. Heart rate, as an increase in heart rate can cause an increase in blood pressure. 2. Size of arteries, as the larger the lumen diameter, the lower the blood pressure. 3. Blood volume, as a decrease in the amount of blood causes low blood pressure. - This can also lead to anemia. - High salt content in food can cause retention of excess water in the blood, which increase the blood volume, and increase blood pressure. 4. Elasticity, as when elasticity decreases, blood pressure increases. 5. Viscosity, as the thicker the blood, the more resistance there is to flow, making blood pressure increase. CARDIAC CYCLE AND HEART SOUNDS CARDIAC CYCLE - The sino-atrial node (aka SA node) is a bundle of specialized nerve and muscle cells located at the junction of the superior vena cava and right atrium. - The SA node can initiate electrical impulses spontaneously. - The atrioventricular node (aka AV node) is a modified cardiac muscle cell mass between the right atrium and right ventricle - The AV node serves as a conductor of nerve impulses. - During diastole (when the atria is contracted and the ventricles are relaxed):  1.​ As blood fills the atria, SA node initiates nerve impulses that are sent across atrial walls (both left and right). 2.​ The atria contract in unison, pushing blood through the AV valves to the ventricles. 3.​ The spreading nerve impulses reach and trigger AV node, which in turn stimulate the Bundle of His. - The Bundle of His are modified muscle fibres in the septum. - During systole (when the atria is relaxed and the ventricles are contracted): 4.​ Bundle of His stimulates the left and right purkinje fibres of ventricles. - Purkinje fibers are specialized heart muscle cells that conduct electrical signals and impulses to the ventricles of the heart 5.​ This finally causes ventricles to contract from the bottom-up, pushing blood through the semilunar valves. - The cycle then starts all over again immediately after ventricular contraction. - The pericardium is the sac that is made of epithelial and fibrous tissue covering the heart. - It contains fluid to reduce friction as the heart beats. HEART SOUNDS - The LUB – DUB sounds of the heart are caused by the closing of the heart valves. - The LUB sounds are the AV valves closing because of the back pressure of the blood created as the ventricles fill up and contract. - The DUB sounds are the semilunar valves as they are forced closed by the back flow of blood in the aorta and pulmonary arteries after the ventricles have contracted. - The DUB marks the end of systole and beginning of diastole, at which time the ventricles empty and relax, and the atria is already filling up. - Closing of valves create sound from the heart. THE ECG/EKG - The electrocardiogram is a device that can see the electrical activity of the cardiac cycle. DISEASES RELATED TO HEARTBEATS - Arrhythmia is when the heartbeats are irregular (e.g. too slow or too fast). - A pacemaker is a a small, battery-powered device that prevents the heart from beating too slowly. - The only way to get a pacemaker is to go under surgery. BLOOD VESSELS AND BLOOD BLOOD VESSELS VESSEL STRUCTURE FUNCTION RELATIVE BLOOD PRESSURE ARTERY - A thick layer of muscle - Carries blood (oxygenated) Highest with some elastic tissue, away from heart to tissues smooth endothelial lining. quickly and under high - The lumen not as large as pressure. veins. - Helps maintain blood pressure and smooth out the pulsing flow of blood due to muscular walls that allow the artery to expand. ARTERIOLE - Smaller than arteries, less - Carry blood away from High, but not as high as elastic, and do not change in heart toward capillaries. arteries. diameter as much as arteries with each pulse of blood. - Have muscle fibers that control blood flow to different capillary beds. CAPILLARY - Very small diameter, but - Distributes blood to all Lowest large enough for red blood cells of the body  cells to travel in single file - The site of nutrient/waste line. exchange with cells. - Capillary wall is one cell thick. VEIN - Thinner walls, thinner - Returns (deoxygenated) Low, but not at low as muscular and elastic lining. blood to heart and serves as capillaries. - Larger lumen diameter a blood reservoir. than arteries. - One-way valves that - Contain regularly spaced prevent backflow of blood in valves. system and cannot be maintained (for pressure) - Blood gets pushed along and through valves by squeezing of skeletal muscles. - Elastic fibers allow veins to expand to accommodate for changing volumes of blood. VENULE - Larger than capillaries, - Gathers blood from Low but smaller than veins. capillaries. - The arterioles, venules, capillary bed are components of the microcirculatory system. - Arterioles are small branches of arteries that regulate blood flow into the capillary bed. - Capillary beds are a network of tiny vessels where nutrient, gas, and waste exchange occurs between blood and tissues. - Venules are small vessels that collect blood from the capillaries and return it to the veins. - The precapillary sphincters are smooth muscle rings at the entrance of capillaries. They control blood flow into the capillary bed by constricting or dilating based on the body's needs. - When they relax, blood flows into the capillaries. - When they contract, blood is diverted directly into venules, bypassing the capillaries. - This system helps regulate blood distribution and optimize exchange in tissues. VASOCONSTRICTION VS VASODILATION - Vasoconstriction is the narrowing of blood vessels. - This means that less blood goes to the tissues when the arterioles constrict. - This results in blood pressure going up. - Examples of vasoconstrictors include caffeine and nicotine. - Vasodilation is the widening of blood vessels. - This means that more blood goes to the tissues when the arterioles dilate. - This results in blood pressure going down.  - Examples of vasodilators include alcohol and nitroglycerine (a drug to help people experiencing pain in the heart, also known as angina). METHODS OF TRANSPORTATION - In arteries, blood is under high pressure from the pumping of the heart. - Muscular, elastic walls help move blood along as the walls expand and recoil after a pulse of blood. - In veins, blood squeezed by contraction of skeletal muscles. - The one-way valves ensure that the blood moves back toward the heart. - Gravity works against venous return in lower limbs and areas below the heart. - Blood pressure differs in arteries and in veins because arteries have blood that is under higher pressure which is maintained by the thick muscular elastic walls, while veins have lower pressure because they are far from the source of the pressure, the walls are less muscular and the lumen is larger. DISEASES RELATED TO BLOOD VESSELS - Varicose veins are swollen, twisted veins that often appear on the legs and feet. - They occur when the valves in the veins, which help regulate blood flow, become weakened or damaged, causing blood to pool in the veins instead of being efficiently returned to the heart. - This can be caused by weak or damaged valves, increased pressure of veins, genetics, and hormonal changes. - This can be treated with sclerotherapy, where during it, a chemical solution is injected directly into the vein. The needle travels up the vein, and as it is pulled back, the chemical is released, causing the vein to form fibrous tissue that collapses the inside of it. BLOOD - Blood is made up of plasma, red blood cells, white blood cells, and platelets. - Plasma carries nutrients, waste, and blood cells throughout the body. - Red blood cells (erythrocyte) transport oxygen from the lungs to the body's tissues and remove carbon dioxide from the tissues back to the lungs. - White blood cells (leukocytes) protect the body from infection and disease by circulating through the bloodstream and attacking bacteria, viruses, and etc. - Platelets help prevent and stop bleeding by clumping together to form a clot at the site where the blood vessel is damaged to stop it from bleeding. - There is 55% plasma, 1% platelets and red blood cells, and 44% red blood cells that make up blood. DISEASES RELATED TO BLOOD - Anemia is when there are low levels of healthy red blood cells to carry oxygen throughout the body. - This can be treated by taking iron supplements and diet changes, as this helps increase the level of iron and hemoglobin (the part of the red blood cells that carry oxygen and remove carbon dioxide). CARDIOVASCULAR DISEASE - The three types of cardiovascular diseases are: 1.​ Arteriosclerosis (REFER TO DISEASES RELATED TO BLOOD PRESSURE)** 2.​ Diseases of the veins (REFER TO DISEASES RELATED TO BLOOD VESSELS)** 3.​ Heart disease HEART DISEASE CORONARY ARTERY DISEASE (CAD) - The coronary artery supplies blood to the heart muscle. - CAD is causes by atherosclerosis, which is a blockage of blood flow in the arteries caused by the collection of plaque. - Plaque is made up of fat and calcium deposits, and is a sticky, yellow substance. - The buildup of plaque in the coronary artery causes the artery to become more narrow, which can increase blood pressure and block the artery completely, so no oxygen or nutrients can reach the heart. - Majority of the time, the coronary artery is not blocked by the plaque, but by the formation of a blood clot (like a scab) on top of the plaque. This can completely shut off the supply of blood to the heart. - If no oxygen or nutrients can reach the heart, the heart can die. - This is known as a heart attack or myocardial infarction. - Symptoms of a heart attack include sharp chest pain, shortness of breath, nausea, and pain in the neck and arm (usually left). - The risk factors of CAD include but are not limited to smoking, lack of exercise, high blood pressure, high blood cholesterol and obesity. HEART ATTACK - There are three ways to diagnose a heart attack: 1.​ Be aware of symptoms 2.​ A blood test, as when muscle tissues in the heart are damaged, certain proteins are made.  3.​ An ECG (aka electrocardiogram) to detect if heart rate/rhythm are normal or if the heart is damaged. - An ECG can tell a cardiologist where the damage occurs, but not how badly the coronary artery is blocked and damaged. - Instead, the cardiologist must do a cardiac catheterization, which involves a small tube (catheter) which dye in it to be seen on an x-ray being inserted into an artery near the groin, which is then threaded through the artery into the blocked area in the coronary artery to identify the location of the blockage. - There are three ways to treat a heart attack: 1.​ An anti-clotting drug, which helps prevent more blockage in coronary arteries. - In minor cases, patients are given aspirin to make blood thinner, and in major cases stronger anti-clogging drugs are provided. - Tubes are inserted into the patient’s nose to increase the concentration of oxygen in the lungs. 2.​ An angioplasty, to which another catheter is inserted through the first catheter. This catheter contains a mesh tube called a stent that stays in the artery and opens it up to prevent it from narrowing. 3.​ Surgery, more specifically coronary bypass surgery. - This procedure takes a vein from another part of the body and attaches it to the heart to bypass the blocked area of the coronary artery to supply blood to the area past the blockage. STROKE - A stroke is caused by a blocked artery in the brain. - Due to the blocked artery, the blood supply to the brain is blocked/reduced, leading to a stroke. RESPIRATORY SYSTEM! PURPOSE OF THE SYSTEM TYPES OF RESPIRATION - Breathing (or ventilation) is the process of moving oxygen rich air in the lungs and carbon dioxide away from the lungs. - External respiration is gas exchange in the lungs. - Oxygen diffuses from the air into the blood stream. - Carbon dioxide diffuses from the bloodstream into the air. - Internal respiration is gas exchange in the cells. - Oxygen diffuses from the bloodstream into each body cell.  - Carbon dioxide diffuses from the cells into the bloodstream to be carried back to the lungs for removal. - Cellular respiration is the process where energy in a cell is made after glucose reacts with oxygen to make carbon dioxide and water. - The word equation for cellular respiration is glucose + oxygen → water + carbon dioxide + energy. - The chemical equation for cellular respiration is C6H12O2 + 6O2 -> 6H20 + 6CO2 + energy. - Cellular respiration releases energy that is used for 64% thermal energy and 34% ATP, which is stored in molecules for cell movement, growth, and building new molecules. GENERAL KNOWLEDGE - It is important for the body to constantly take oxygen in so it can obtain energy for the cells and tissues. - The respiratory membrane depends on the size of animals, as the bigger the animal is, the larger the respiratory membrane. - This is because a larger respiratory membrane can provide the animal with a good source of oxygenated blood. - All the volumes that make up the total lung capacity are: - Inspiratory reserve volume, which is the volume of air that can be inhaled after a normal inhalation. - Expiratory reserve volume, which is the amount of air that can be forcibly exhaled after a normal exhalation. - Residual volume, which is the volume of air remaining in the lungs after a forced exhalation. This also prevents the lungs from collapsing. ANATOMY AND FUNCTIONS OF RESPIRATORY SYSTEM ANATOMY FUNCTIONS OF PARTS 1. The nostrils allow air to enter to the body. 2. The nasal cavity filters, moistens, and warms the air. The conchae helps increases the surface area of the nasal cavity to help warm, moisten, and filter more air. ​ 3. The pharynx helps direct air into the larynx and helps prevent food from entering the respiratory tract. 4. The epiglottis is a flap of tissue that covers the larynx when food is being swallowed, preventing them from entering the trachea. 5. The larynx has vocal cords inside and is a passage way for air to go into the trachea. 6. The trachea is a tube that conducts air from the larynx to the bronchi (plural for bronchus). - It is lined with cilia that trap dust and particles, moving them upwards to the pharynx to be expelled. - The cartilaginous rings provides structural support to the trachea to prevent it from collapsing while maintaining an open airway for air passage. 7. The bronchus branches off from the trachea and directs air to each lung, and further divide in smaller bronchi (bronchioles). 8. Bronchioles help distribute air throughout the lungs, and are lined with smooth muscle to regulate airflow. 9. The alveoli are tiny air sacs at the end of bronchioles where gas exchange occurs. - Oxygen from the air diffuses into the blood, and carbon dioxide from the blood diffuses into the alveoli to be exhaled. 10. The lungs are the organs that where gas exchange occurs in. - Oxygen is absorbed into the blood in the lungs, and then carbon dioxide is expelled. - The right lung has three lobes, while the left lung has two lobes. 11. The ribs protect the lungs and heart, and their movement during breathing helps expand and contract the thoracic cavity. 12. The intercostal muscles are muscles that located between the ribs and assist in breathing by expanding and contracting the chest cavity. - The external intercostals help elevate the ribs during inhalation, while the internal intercostals aid in exhalation. 13. The diaphragm is the primary muscle involved in breathing. - When it contracts, it moves downward, expanding the thoracic cavity and allowing air to flow into the lungs. - During exhalation, it relaxes, helping to expel air from the lungs. 14. The heart pumps oxygenated blood from the lungs to the rest of the body and pumps deoxygenated blood to the lungs for gas exchange - The thoracic (chest) cavity refers to the cavity that contains the lungs and heart. - The abdominal cavity refers to the cavity that contains organs and glands of digestion, excretion, and reproduction. MECHANICS OF BREATHING BREATHING MOVEMENTS INHALATION - This refers to the taking in of air. 1. The ribes move upward and outward, as the diaphragm moves downward. 2. The volume is increased in the lungs. 3. The pressure in the lungs is decreased. 4. The air enters the lungs to equalize pressure. - The contraction of the diaphragm and the intercostal muscles increase the volume in the thoracic cavity.  - This increases the volume in the lungs. - Air enters the lungs as air moves from high to low pressure. - The abdominal muscles help the diaphragm contract and move. EXHALATION - This refers to air exiting the lungs. 1. The ribes move inward and downward, as the diaphragm moves upward. 2. The volume is decreased in the lungs. 3. The pressure in the lungs is increased. 4. Air is forced out of the lungs due to pressure in the lungs. - The relaxation of the diaphragm and intercostal muscles decrease the volume of the thoracic cavity. - This decreased the volume in the lungs. - The abdominal muscles help the diaphragm move up in exhalation. - Air leaves the lungs as the abdominal muscles contract and push against the diaphragm, as well as moving from high to low pressure.