Anatomy, Physiology and Disease Chapter 3 The Cells: The Raw Materials and Building Blocks

1. Anatomy, Physiology and DiseaseChapter 3The Cells: The Raw Materials and Building Blocks

2. Overview of Cells • Cells are formed from chemicals and structures • Cells are found in all living things • Some nerve cells can be 2 feet long or longer • Cells can be flat, round, thread like, or irregularly shaped • 7.5 trillion cells found in body work together to allow for proper functioning of body

3. Figure 3-1 Various types of cells within the human body

4. Cell Structure • Certain common traits that almost all cells share: • Nucleus • Organelles • Cytoplasm • Cell membrane

5. Figure 3-2 Cellular components

6. Cell Membrane • Defined boundary that possesses a definite shape and actually holds cell contents together, acting as protective covering • Allows material in and out of cell • Selectively permeable because they choose what gets in or out • 3/10,000,000 of an inch thick Example: Electrolytes Na Sodium K Potassium Cl Chloride Co2 Carbon Dioxide Na & K Pump

7. Figure 3-3 The cell membrane Na & K Pump

8. Transport Methods • Moving things in and out of cell can be done in two broad ways: • Passive transport: requires no extra form of energy to complete • Active transport: requires some addition of energy to make it happen

9. Transport Methods (cont’d) • Passive transport can be divided into four types: • Diffusion • Osmosis • Filtration • Facilitated diffusion

10. Diffusion • Most common form of passive transport in which substance of higher concentration travels to area of lesser concentration • Examples: • Adding packet of powdered drink mix to pitcher of water • Smell of classmate’s perfume filling room • Necessary to move oxygen from lungs to blood stream, or carbon dioxide from blood stream to lungs

11. Figure 3-4 Two examples of diffusion

12. Osmosis • Another form of diffusion in which water travels through selectively permeable membrane to equalize concentrations of a substance • Dissolved substance called a solute

13. Osmosis cont • Water tends to travel across a membrane to equalize concentrations of a solute; ability of substance to pull water toward area of higher concentration called osmotic pressure • The greater concentration of solute, the greater osmotic pressure, or pull, it exerts to bring in water

14. Filtration • Differs from osmosis in that pressure is applied to force water and its dissolved materials across membrane • Similar to rush of people pushing through turnstile during rush hour • Example: pumping of heart, which forces blood flow into kidneys, where filtration takes place

15. Figure 3-6The process of filtration in the kidneys, where smaller solutes such as the electrolytes sodium and potassium pass through the membrane, while the larger blood protein and cells normally do not.

16. Facilitated Diffusion • A variation of diffusion in which a substance is helped in moving across the membrane, similar to an usher helping you to your seat • Glucose is the substance that is often passed into our bodies • It can be imagined as moving into an already revolving door – once it steps into the door it is pushed along by Insulin.

17. Pathology Connection: Cystic Fibrosis • Incurable, fatal genetic disease affecting 1/3000 Caucasian babies

18. Cystic Fibrosis (cont’d) • Etiology: malformation in membrane channels for chloride and sodium ions • Sodium and chloridedo not diffuse across cell membrane as they normally would • Fluid around cells becomes extremely salty due to excess sodium and chloride • Results in excessively thick mucus in respiratory, digestive, and reproductive systems; mucus can cause clogging in organs

19. Cystic Fibrosis (cont’d) • S/S may include • Difficulty breathing (SOB) • Nutritional deficits due to decreased absorption of nutrients • Increased risk of respiratory infection • Diabetes • Infertility (especially in males)

20. Cystic Fibrosis (cont’d) • RX: • No cure; treatments help extend and improve quality of life • Nutritional supplements • Antibiotics to prevent pneumonia • Mucus thinning drugs (Mucomyst-Ascetlsysteine) • With treatment today, average life span of patient is 35 years

21. Cystic Fibrosis (cont’d) • Diagnosis • Prenatal genetic testing • Postnatal genetic testing • Testing pulmonary function • Testing amount of sodium in sweat

22. Pathology Connection: Diabetes Mellitus • Lack of glucose transport into cells causes several problems • Lots of glucose hangs around in bloodstream, causing big osmotic problems for cells • Cells can’t make as much energy as they need when glucose can’t be transported

23. Types of DM • Type I results from the body's failure to produce insulin. 5-10% of diabetics have type I diabetes. Must take insulin to survive. • Type II results from Insulin resistance, a condition in which cells fail to use insulin properly. Most Americans who are diagnosed with diabetes have type 2 diabetes • Gestational: Pregnant women who have never had diabetes before but who have high blood sugar (glucose) levels during pregnancy. Affects about 4% of all pregnant women

24. Endocytosis • Used by cells for intake of liquid and food when substance too large to diffuse across membrane • Examples: • Phagocytosis: name for process if solid particle being transported • Pinocytosis: name for process if water being transported

25. Exocytosis • Transport of things out of cell • Some cells produce substance needed outside cell • Once substance is made, it is surrounded by membrane, forming a vesicle, and moves to cell membrane • Vesicle becomes part of cell membrane and expels its load out of cell

26. Pathology Connection: Familial Hypercholesterolemia • Blood cholesterol too high; caused by poor diet and exercise or inherited • Normally low density lipoprotein (LDL or “bad cholesterol”) binds to cholesterol, and allows it to be carried into cells via endocytosis; once inside, cholesterol used to make other lipids

27. Familial Hypercholesterolemia cont’d • LDL doesn’t move into cells, and stays in blood; causes 2 problems • Too little cholesterol gets into cells, and cells must make more cholesterol • LDL that cannot get into cells hangs around in blood; causes plaques in blood vessels which can lead to blood clots, strokes, and heart attacks • RX with diet modifications and cholesterol lowering drugs • 1/500 Americans have moderate form

28. Phagocytosis, Pinocytosis & Exocytosis

29. Cytoplasm • Gel-like substance composed of water, nutrients, and electrolytes, which looks a lot like white of raw egg • Required by cells for their internal environment to thrive and function

30. Nucleus • “Brains” of cell • Dictates activities of other organelles in cell • Has double walled nuclear membrane preventing materials from entering

31. Nucleus (cont’d) • Chromatin • Contains deoxyribonucleic acid (DNA); DNA contains blueprints, or specifications, for creation of new cells • Will eventually form chromosomes, which contain genes • Genes determine our inherited characteristics

32. Nucleus (cont’d) • Nucleolus • Spherical body made up of dense fibers found within cell nucleus • Major function is to synthesize ribonucleic acid (RNA) that forms ribosomes

33. Ribosomes • Organelles found on endoplasmic reticulum or found floating around in cytoplasm • Made of ribonucleic acid (RNA) and assist in production of enzymes and other protein substances needed for cell repair and reproduction • Can be considered “remodeler” of cell, taking existing structure and maintaining and repairing it

34. Centrosomes • Act as building contractor, building new structures as need arises • Contain centrioles that are involved in division of cell • Centrioles are tubular shaped and usually found in pairs

35. Mitochondria • Tiny bean-shaped organelles, act as power plant to provide up to 95% of bodies’ energy needs for cellular repair, movement, and reproduction • If cell needs more power, it increases number of mitochondria in cell • Liver cells, which are quite active, have up to 2,000 mitochondria in each cell

36. Mitocondria cont’d • Contain special enzymes that help to take in oxygen for use in producing energy • Energy produced is in form of ATP (adenosine triphosphate) created by mitochondria

37. Endoplasmic Reticulum • Series of channels set up in cytoplasm that are formed from folded membranes • Has two distinct forms: • One has sandpaper-like surface, with ribosomes on it, called rough endoplasmic reticulum; responsible for synthesis of protein • Second form has no ribosomes and appears smooth, called smooth endoplasmic reticulum; synthesizes lipids and steroids

39. Golgi Apparatus • Looks like a bunch of flattened membranous sacs • Once protein from the endoplasmic reticulum is received, it further processes and stores it • Takes processed protein to cell membrane where it is released • Salivary glands and pancreatic glands have higher numbers of Golgi apparati because they have higher level of secretion or storage

40. Lysosomes • Organelles containing powerful enzymes that take care of cleaning up intercellular debris and other waste • Lysosomes help keep us healthy; they destroy unwanted bacteria by participating in process of phagocytosis

41. Other Interesting Parts • Vesicles: vans which take stuff & travel to other sites within cell • Cytoskeleton: provides shape to cell and allow cell and its contents to be mobile • Flagella: whip-shaped tails that move some cells, like sperm, to other locations • Cilia: hair-like projections located on outer surface of some cells; move particles using wavelike motion

42. Pathology Connection: Organelle Disorders • Lysosomal storage disorder • Occur when lysosomes missing one of their enzymes • Results in some molecules not breaking down and accumulating in cells • Many kinds of lysosomal storage disorders • All are genetic • Most lack effective therapies

43. Pathology Connection:Tay Sachs Disease • Enzyme missing in lysosomes of nervous system cells • As result, glycoproteins accumulate in cells in nervous system • Build up causes inflammation and eventual cellular destruction • Symptoms includemental regression, dementia and paralysis appearing within first year of patient’s life • Found mostly in Ashkenazi Jews: German Jews

44. Tay Sachs con’t • Diagnosis: appearance of cherry red spot on back of patient’s eyes; abnormalities in startle reflex • No treatment; disease generally fatal within two or three years of onset • Availability of genetic test has decreased incidence in recent years

45. Pathology Connection:Cigarettes and paralyzed cilia • Smoking causes cilia in respiratory tract to become paralyzed • As a result, cannot keep lungs clean • Over time, can lead to chronic obstructive pulmonary disease (COPD) and other smoking-related lung problems • Passive smoking (second hand smoke exposure) also increases risk of lung problems

46. Enzymes • Facilitate important chemical reactions in body • One way is by speeding up reactions • Not used up by reactions that they facilitate; instead, act like carrier molecules • Very specific; each only facilitates (catalyzes) certain reactions

47. Pathology Connection: Phenylketonuria (PKU) • Genetic condition; enzyme disorder • Most common inCaucasians of Irish, Scottish, or Scandinavian descent • Patients missing enzyme: phenylalanine hydroxylase • Without enzyme, amino acid phenylalanine builds up in cells • Build up affects nervous system; causes progressive mental retardation if not treated

48. Phenylketonuria (PKU) con’t • Other signs include • Light pigmentation of skin, hair and eyes • Abnormalities of posture and gait • Epilepsy • Diagnosis • Blood tests & genetic tests • Every newborn in US routinely screened

49. Phenylketonuria (PKU) con’t • Treatment: low phenylalanine diet includes avoidance of high protein foods and products sweetened with aspartame (NutraSweet™) • Consequences of going “off diet” • Children: cognitive defects • Adults: depression, anxiety, or other neurological changes

50. Pathology Connection: Cancer • When body is healthy, cells grow in orderly fashion; control system prevents cells from reproducing too fast • Sometimes conditions are altered that trigger changes in way cells reproduce; this wild, uncontrolled reproduction can lead to too many cells being produced, creating a lump, or tumor • Tumors can generally be either benign or malignant !!!