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Cell Parts - Cell membrane: protective barrier that holds everything in, regulates exchange of substances and communicates with other cells - The membrane is made of the phospholipid bilayer: the outsides are hydrophilic, the inside is hydrophobic - Substances move across using diffusion: particles ...

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Biology Notes Cell Parts - Cell membrane: protective barrier that holds everything in, regulates exchange of substances and communicates with other cells - The membrane is made of the phospholipid bilayer: the outsides are hydrophilic, the inside is hydrophobic - Substances move across using diffusion: particles go from high to low concentration until an equilibrium is reached - Cytoplasm: jelly-like substance that fills the cell - Contains nutrients, allows organelles to move around - Nucleus: control center of the cell - Controls growth and reproduction - Surrounded by the nuclear envelope, which has pores to allow the transport of substances - Nucleolus: small dense area inside nucleus that contains most of the cell’s DNA (contains the information for making proteins and other molecules) - Chromatin: long, thin substance that contains protein and DNA, condenses to form chromosomes during cell division - Vacuoles: membrane-bound organelles that store nutrients, wastes, etc. - In plants, the central vacuole contains water, and swells when water enters the cell, causing the plant cell to become firm - Vesicles: transport substances throughout the cell - Mitochondria: use cellular respiration to convert chemical energy in sugar into energy that the cell can use - Lysosomes: where digestion takes place - Small circles with dots - Filled with enzymes (proteins that are natural catalysts) for speeding up chemical reactions involved with digestion - Break down invading bacteria and damaged organelles - Golgi apparatus: receives proteins from the endoplasmic reticulum - Looks like a stack of pancakes - Modifies, sorts, packages cells for transport within and beyond the cell - Endoplasmic reticulum: has interconnecting tubes that transport substances throughout the cell - Rough ER has ribosomes on the surface (makes proteins) - Smooth ER doesn’t have ribosomes on the surface (makes oils and fats) - Ribosomes: small spherical organelles that are attached to the rough ER or float freely inside the cytoplasm, assemble proteins - Cytoskeleton: network of fibres of proteins, maintains the cell’s shape - Cell wall: only in plants, it’s a rigid frame that provides support, protection, and strength - Chloroplasts: only in plants, contain chlorophyll which uses energy from the sun

Biology Notes to convert CO2 and H2O into sugar and O2 (photosynthesis) - Made of little sacs called thylakoids, which are stacked into groups called grana (sing. granum) - The thylakoids are surrounded by a thick sac called a stroma - Animal cells have cilia (flagellum) for movement, while plant cells don’t Cell Division - Used for: - Reproduction - Growth - Tissue repair - Rate of cell division varies by type of cell (skin cells divide fast, muscle cells do not) - When an organism grows, its number of cells increases, the original cell does not get larger because it wouldn’t have enough surface area to sustain the necessary diffusion rate to transport substances around - Cells replace old or damaged cells - Human body cells - somatic cells - e.g. skin cells - 46 chromosomes - Human sex cells - gametes - e.g. eggs - 23 chromosomes - Only somatic cells undergo mitosis - Chromosomes are made of DNA - They’re made of 2 sister chromatids tied together at the centromere - A gene is a segment of DNA that controls protein production, determines your physical traits - Before mitosis, the parent cell has to duplicate its DNA, by duplicating each chromatid to form a chromosome - Diploid number: # of chromosomes in somatic cells - Human diploid number is 46 - Haploid number: # of chromosomes in gametes - Human haploid number is 23 - A zygote is a unicellular organism formed when a sperm fertilizes an egg - After lots of mitosis, the zygote becomes you The Cell Cycle - Interphase -> G1 + S + G2 and then Mitotic (M) phase -> mitosis + cytokinesis - Interphase accounts for ~90% of the cell cycle - In G1, cell grows, builds organelles and proteins - In S, cell duplicates DNA - In G2, cell grows, prepares for mitosis Mitosis - Happens only in somatic cells - Prophase, prometaphase, metaphase, anaphase, telophase, finished by cytokinesis

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In prophase, centrosomes (each consisting of 2 centrioles) move apart and mitotic spindle grows out of them Prometaphase: the two centrioles are at opposite ends of the cell, the nuclear envelope starts breaking down Metaphase: chromosomes lie in the center of the screen, spindle fibers from either end of the cell attach to the centromere of each chromosome Anaphase: sister chromatids separate and move to the opposite poles Telophase: chromosomes start unravelling to form strands of chromatin, spindle fibers break down, nuclear membrane reappears

Cytokinesis: in animals, a cleavage furrow forms and pinches in using proteins that contract in a ring shape - In plants, a cell plate forms and the Golgi body starts making small vesicles to carry the substances needed for the new cell plate - Eventually, the cell plate becomes the cell wall Cancer - Cancer is when cells grow and divide too fast and out of control - Can be both hereditary or caused by environmental factors - A tumour is a mass of useless cells that keep dividing and growing - A benign tumour does not affect surrounding tissues, a malignant tumour interferes with nearby cells (e.g. by producing unwanted hormones) - Metastasis is the process of cancer cells breaking away from the primary tumour and establishing a secondary tumour somewhere else in the body - Cancer is caused by a mutation during mitosis that alters the part of DNA that deals with cell division - Carcinogens are environmental factors that cause cancer (e.g. cigarette smoke, radiation) - Pap test: test where a doctor takes a sample of an adult woman’s cervical cells to check for signs of cervical cancer - Leukemia is blood cancer, when there are too many white blood cells - Cancer is diagnosed with blood tests, imaging tests (CT scans, MRI), and biopsy (sample of cells examined under microscope) - Cancer can be treated by:

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Surgery: removing the tumour Chemotherapy: using drugs to kill the harmful cells Radiation: ionizing radiation damages the harmful cells’ DNA, so they can no longer keep dividing - Biophotonics: new technology that uses light beams to detect and treat cancer Cell Specialization - Specialized cells: cells that can perform a specific task - Muscle cells need more energy -> more mitochondria - Nerve cells have multiple connections (branches) - Epidermal cells on young plant roots have hairs that absorb water from soil Circulatory System - The big 3 parts of the system: - Heart - Blood - Blood vessels - Functions: - Carries O2 - Removes CO2 - Maintains temperature - Prevention of infection - Carries nutrients (from intestines) - Carries cellular wastes (to kidneys) - Blood clotting (so u dont die of blood loss lol) - Blood travels in vessels in all times for efficiency, in 3 pathways: - Systemic pathways (to and from organs) - Pulmonary pathway (to and from lungs) - Cardiac pathway (to and from heart) - Blood is made of: - Red blood cells - White blood cells - Platelets - Plasma - The plasma makes up 55% of the blood, and is a fluid that’s mostly water with some nutrients, wastes, proteins, hormones, and antibodies - The rest of the blood is the solid part: - Red blood cells: carry oxygen using hemoglobin - AKA erythrocytes - Smooth donut-like shape to allow easy transport inside vessels and to increase surface area to store more O2 and CO2 - No nucleus

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Hemoglobin (red protein that contains iron) that is used for storing O2 - White blood cells: attack invaders (like bacteria) - AKA leukocytes - Macrophages destroy the bad bois by eating em (phagocytosis) - Platelets: control blood clotting - AKA thrombocytes - React with substances in plasma to form a clot (thrombus) so u dont run outta bloodcentrifug - Blood can be separated in a e If too little RBCs it leads to anemia, you’ll feel tired, caused by bleeding, iron deficiency (so not enough hemoglobin to store O2) If too many WBCs, it is a sign that the body is fighting an infection, is a symptom of leukemia Blood vessels: - Arteries: carry blood away from heart - High pressure - Have thick walls of muscle and tissue - You can feel this immense pressure as your pulse - Arterioles are smaller arteries, with lower pressure, which eventually connect to capillaries - Veins: bring blood back - Veins have thinner walls than arteries (lower pressure) - Have muscles to help blood return to the heart - Venules are smaller veins - Capillaries: connect the two - Extremely narrow - One RBC can fit through at a time. (!!!) - Very low speed, very low pressure - Allows O2 to diffuse to tissues and CO2 to diffuse from - Eventually merge into venules Heart’s avg BPM is 72, weighs 300 g Right side of the heart pumps blood to lungs to pick up O2 Left side of the heart pumps oxygenated blood to the body

Respiratory System - Functions: - allows you to obtain O2 and get rid of CO2 - Enables speech - Inspiration (inhale) and expiration (exhale) - You breathe on avg 15 times/min, 10000L of air every day

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Internal respiration: - All cells need oxygen for metabolism - All cells need a way to get rid of CO2 - Gas exchange at the cellular level External respiration: - Ventilation: exchange of air between lungs and atmosphere - Gas exchange happens in the pulmonary capillaries - Breathing is mostly involuntary Organs in the system: - Nose/nasal cavity: warms, moistens, filters air as it is inhaled - Mucous membrane - Nasal septum: cartilage and bone separating the two nostrils - Olfactory receptors: detect odor, located in the nasal cavity - Pharynx (throat): leads to trachea - Nasopharynx: where the pharyngeal tonsils (AKA adenoids) are located - Oropharynx: where palatine tonsils are located - Laryngopharynx: where the larynx is located - Epiglottis: a flap that covers the larynx and trachea so food does not enter the lungs - Larynx: voice box - Glottis: the apparatus that produces sound - Trachea (windpipe): has fine hairs called cilia which filter air before it reaches the lungs, mucous membrane - Has smooth muscle with c-shaped cartilage rings to move air along and keep structure, respectively - Bronchi: two branches at the end of the trachea, each leads to a lung - Have smooth muscle with c-shaped cartilage rings - Bronchioles: smaller branches from the bronchi that lead into the lungs and eventually to the air sacs - Alveoli: the air sacs where gases are exchanged - One cell thick - Lungs: 3 lobes in the right, 2 lobes in the left Thoracic cavity: the chamber of the body protected by the ribcage - The mediastinum is the middle part of the cavity, and houses heart - It also houses the thymus, which is an organ important to the immune system Pleura: thin fluid-filled membranes that enclose each lung - Parietal pleura: outer - Visceral pleura: inner - Pleural cavity is the area surrounding each lung

Biology Notes - Contains lubricating fluids - Tissues of the system: - Epithelial tissue that traps dirt with mucous - Also has cilia to move mucous and foreign material out - Breathing: involves the diagram (large sheet of muscle under the lungs) and the muscles - Controlled by a part of the brain that detects the concentration of CO2 in our blood - When you inhale, lungs have low pressure - When you exhale, lungs have high pressure - During exhalation: - Diaphragm relaxes and moves upward - Rib cage moves downward - Decrease in volume in chest cavity causes high pressure in lungs, air goes out - Diaphragm: a muscle that separates the organs of the chest cavity from the abdominal cavity - Intercostal muscles: muscles between the ribs that raise or lower the rib cage - Respiratory cycle: - Human respiration rate (breaths/min) controlled by a part of the brain called the medulla - Normal respiration rate for an adult is 14-20 breaths/min - Increased rate = hyperventilation - Decreased rate = hypoventilation - Path of air: nostrils (filtered) -> nasal cavity (warmed and humidified) -> pharynx -> larynx -> trachea -> bronchi -> bronchioles -> alveoli - Diseases: - Asthma: severe allergic reaction where the bronchioles constrict - Treated with corticosteroids using puffers - Difficulty breathing, coughing - Bronchitis: inflammation of lining of bronchioles - Emphysema: condition where alveoli deteriorate, so the lungs lose their elastically - Pneumonia: condition where alveoli become filled with fluid, preventing the exchange of gases - Lung cancer: tumours in the lung - One major cause is tobacco use, which contains carcinogens - Tuberculosis: infectious disease caused by bacteria in the lungs - Severe acute respiratory disease: disease of respiratory system Musculoskeletal System - Made of bones and skeletal muscles

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Body is made of 206 bones, 300 at birth (some fuse together to form e.g. skull) Longest bone in body is femur Smallest bone in body is stirrup Males have thicker and longer limbs, females have a wider pelvis Osteoblasts create bone, osteoclasts destroy it Main functions of the skeleton: - Give structure, support, general stability - Protection of important organs - Some bones (e.g. femur, skull, sternum) have red blood marrow that produces RBCs, WBCs and platelets - Stores phosphorus and calcium until needed by the body - Movement (skeletal muscles) Two parts of the skeleton: - Axial skeleton: protects important organs - skull, spinal cord, ribcages - Appendicular skeleton: bones that are used for body movement Five types of bones: - Long bones - long arm and leg bones - Short bones - mostly wrist and ankle bones - Flat bones - flat and thin bones (e.g. skull, ribs) - Irregular bones - odd bones like vertebrae - Sesamoid bones - free floating bones inside tendons (e.g. patella) Ossification: process of new bone formation Re-modelling: when changes to the bone formation occur Fracture: when a bone breaks due to disease, infection, malnutrition, or excessive forces Young children have weaker bones because they are more flexible Older people can have weaker bones because of loss of calcium due to nutrition and decreased physical activity Stress facture: tiny cracks in the bone due to stress (because of too much, too soon, too fast) Osteoporosis: deterioration of bone tissue that leads to increased possibility of fractures - Especially happens in older people (mostly women) - Often lead to hip, spine, and wrist fractures - Good nutrition (calcium and Vit D) and moderate exercise can help prevent it Muscle is 30-40% of body mass More than 600 muscles in the human body All muscles work in agonist-antagonist pairs - Agonist: primary joint mover - Antagonist: acts against the agonist

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- E.g. biceps (agonist) and triceps (antagonist) Functions of muscle - Movement - Support - Stability and balance - Heat production - Shivering - Life sustaining activities - Heart beating and blood pressure control - Digestive movement Muscular system - Muscle is connective tissue that can contract and relax Three types of muscles: - Smooth muscle (involuntary, e.g. digestion) - No striations (stripes) - Cardiac muscle (heart muscle) - Striated - Skeletal muscle (voluntary movements) - Striated (striped) - Attached to skeleton - Tire easily unlike the other two muscle types Groups work together for fine control and balance of a movement (agonistantagonist pairs) Knee joint: - Medial (on the inside), lateral (on the outside) collateral ligaments (on the front) - Posterior (inside), anterior (outside) cruciate ligaments (on the back) Tendons: made of collagen (white fibrous protein) - Attach muscle to bone Ligaments: - Tough bands of white, fibrous tissue - Attach bone to bone - Flexible, not elastic - Limits movement in undesirable directions Cartilage: - Smooth elastic tissue - Found at the end of long bones - Protects and covers joints - Provides structure to things like the trachea Strains, pulls, and tears: - Torn ligaments/tendons result from twisting and sprains

Biology Notes - Fibres can be tore completely - Pulls/strains happen on muscles - Ligament inflammation - Caused by irritation from prolonged use - Sometimes from bacterial infection or occupational hazard Nervous System - Purpose: to sense the environment and coordinates a response to it - Made of the brain, spinal cord, and peripheral nerves - Central nervous system: - Brain and spinal cord - Protected by bones - Skull protects the brain and spine protects the spinal cord - Cerebrospinal fluid surrounds the brain and spinal cord, cushions against injury and transports substances like chemicals and waste - Peripheral nervous system - Has the nerves that connect the body to the CNS - Relays information about the internal and external environments of the brain - Subdivisions: - Nerves that control voluntary muscles - Nerves that carry information from sensory organs - Nerves that regulate involuntary functions like breathing - Nerves are bundles of cells called neurons, surrounded by connective tissue - Neurons are specialized cells for communication - Neurons do not undergo mitosis (except sometimes in the PNS) - Signals travel at like 180 mph - Nerve cells: - Nerve cells send signals through their axon - Attached to dendrites of other cells - Continues until reaches muscle cells - Signal only goes in one direction - Myelin sheath - Fatty material surrounding the axon - Acts like an electric wire preventing electrical impulses from passing to the wrong neuron - Special cells receive input from our external environmental and send signals along our PNS to our CNS - Ears, mouth, nose, muscles and skin - Other receptors detect pressure, temperature and pain - They also make us aware of our balance, position, and motion - Reflexes: actions that do not require the involvement of the brain

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Happen w/o conscious thought Spinal cord acts as a shortcut for reflexes (so the signal does not go all the way to the brain) Function MRI: detects electrical activity in the brain Multiple sclerosis: destroys myelin sheaths so that signals are mixed up - Can result in paralysis, concussions - Viruses and bacteria can also cause permanent damage in the brain and nervous system Congenital analgesia: - Insensitivity of pain - Caused by a malfunction of pain signal pathways to the brain or the brain’s inability to interpret these signals

Organ Transplantation - Organs that can be transplanted: - Heart - Lungs - Liver - Kidney - Pancreas - Intestines - Tissues that can be transferred - Corneas - Heart valves - Veins - Skin - Bone - Ligaments - Cartilage - Tendons - Benefits: - The recipient can live a healthy life - The donor or their family can feel satisfied that they saved someone’s life - Medical researchers have learned more about the human body as a result - Risks: - The recipient’s immune system may recognize the new organ as foreign and try to destroy it - To minimize risks: - Use tissues that match as closely as possible - Use drugs that prevent the immune system from rejecting the new tissue or organ

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- But, these drugs may also suppress the immune system (!!!) Living donor organs come from a living person - A lung transplantation requires two donors, one donor for a left lung lobe and one donor for a right lung lobe - A kidney transplant requires only one donor - A liver transplant requires the removal of one lobe, eventually that single lobe will regenerate tissue and function as a complete liver Donors are ideally relatives of the recipient so that there is a greater chance that the organ is a genetic match and so that the wait time is less One risk for organ donors is that if their remaining organ fails, they no longer have a back up Deceased donor organs come from deceased people...