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TOPIC 11: Animal Physiology, 1) B lymphocytes (B cells) are antibody…

- - - - eliminated = disease stops circulating in a region
        eradicated = disease is eliminated worldwide.
        SMALLPOX was targeted for erradication by WHO: it is an easily identifiable disease and transmission only occured by direct contact.
      - vaccination programmes have lead to a reduction in the incidence of infectious diseases (epidemiology is the study of patterns cause and effects of health and osease conditions in a population).
      - imrpovement of healthcare services, public sanitaiton (apart from vaccination) will also impact infectious disease rates.
    - - A zoonosis is a pathogen which can cross a species barrier.
        
        this is a global concern. the major factor contributing to the increased appearance of zoonic disease is the growth contact between animal lifestock and humans.
    - - an allergen is an environmental substance that triggers an immune response.
        
        mast cells are immune cells found in connective tissue that secrete histamine in response to infection.
        
        histamine is a chemical produced by mast cells in response to allergen.
        histamine can also be produced by basophils (WBC).
      - histamines causes the dilation of small blood vessels in the infected area cuasing the vessels to become leaky. increasing the flow of fluid containing immune components to the infected area.
      - Histamines cause allergic symptomps
        
        The release of histamine by mast cells causes an inflamatory response that results in allergic symptoms.
        
        histamine also produces allergic rashes or swelling that can lead to anaphylaxis
        
        anti histamines can be taken to decrease the effects of the allergic response.
        
        Itchy nose.
        
        Sneezing.
        
        Runny nose.
    - - Monoclonal antibodies are highly specific antibodies that are produced by a clone of cells, derived from a single cell.
      - to produce monoclonal antibodies, b-cells/plasma cells are fused to tumour cells to make hybridoma cells which can endlessly divide.
      - MONOCLONAL ANTIBODIES ARE PRODUCED BY HYBRIDOMA CELLS.
        
        a. mice injected with one type of antigen;
        
        b. cells from the spleen are removed;
        
        c. plasma cells that produce antibodies (are used);
        
        d. tumor cells that divide endlessly (are used);
        
        e. fusion of plasma cells with tumor cells / fusion produces hybridoma cells;
        
        f. selection of hybridoma cells;
        
        g. hybridoma cells are cultured in a fermenter;
        
        h. (hybridoma) cells divide endlessly and produce the desired antibodies;
      - Monoclonal antibodies to HCG are used to pregnancy test kits
        
        monoclonal antibodies can detect hCG. hcg is produced during pregnancy
        
        the urine of a pregnant woman contains hCG
        
        monoclonal antibodies can detect this
- - - - The grasshopper has 3 pairs of appendages. The exoskeleton of the hind leg is divded into the femur, fibia and tarsus 1) femur --> fibia --> tarsus
      - As the grasshopper jumps = when the extensor muscle contracts the flexor muscle relaxes = tibia elonagates.
        when the extensor muscle relaxes the flexor muscle contract = tibia flexes
        so extensor muscle is antagonistic to flexor muscle
      - The hind limbs of grasshoppers are specialized for jumping
  - - - muscle fibres contain a specialised rough endoplasmic reticulum called the sarcoplasmic reticulum that extends along the muscle fibre. this reticulum wraps around the myofibrin and contains calcium for muscle contractions and many atp.
    - - myofibrils are long striated structures inside muscle fibres with black and white bands.
      - each myofibril is made up of contractile sarcomeres.
        
        Myofibrils – rod-shaped bodies consisting of actin and myosin filaments
        
        Sarcolemma – plasma membrane of the muscle cell
        
        Mitochondria – large numbers; found dispersed around individual myofibrils
        
        myobrils contain repeating contractiel units called sarcomeres composed of two protein myofilaments
        
        Contains the thick filament (myosin) and thin filament (actin)
        
        Myosin contains a head which binds to the binding site on the actin; interaction between myosin and actin (cross-bridge) is responsible for muscle contraction
        
        Myosin is seen as dark bands while actin is seen as light bands
        
        Actin filaments are attached to a Z-line at one end
        
        Each mysosin filament is surrounded by six actin filaments
        
        A bands contain a full length of myosin and some of the actin filaments
        
        I bands contain only actin filaments. A band contains only myosin
        the H zone dissapears in contraction and shows the thick mysoisn filament.
        
        btw one sarcomrere shows two z lines with actin and mysosin in the middle
      - The contraction of the skeletal muscle is achieved by the sliding of actin and myosin filaments.
        
        during muscle contractions the myosin filaments pull the actin filaments inwards towards the centre of th sarcomere, allowing the sarcomere to shorten in length and the overall length of the muscle fibre = skeltal muscle
        
        a. actin and myosin slide past each other; mysosin heads pull actin filaments towards the centre
        
        b. action potential/depolarisation/nerve impulse arrives at end of motor neurone;
        
        c. neurotransmitter/acetylcholine released causing action potential (in muscle fibre);
        
        d. sarcoplasmic reticulum releases calcium ions;
        
        e. calcium ions cause binding sites on actin/for myosin to be exposed;
        
        f. myosin heads bind to sites on actin/form cross-bridges;
        
        g. myosin (head) moves actin filament using energy from ATP;
        
        h. actin moved towards the centre of sarcomere/M line/M band;
        
        i. sarcomeres shortened;
        
        j. (binding of) ATP causes release of myosin head from actin;
        
        k. conversion of ATP to ADP and Pi causes myosin heads to change angle;
        
        l. cycle (of events) repeated (during muscle contraction);
        
        cross bridges are formed as myosin heads bind to actin filaments = ligth band shortens in length but darker one remains same length
        (relaxed sarco has large light bands and z line is wider apart)
        (contracted sarco has shorrten light bands and a small z line)
        
        Calcium ions and the proteins tropomyosin and troponin control muscle contractions.
        
        in relaxes muscle tropomyosin blocks binding sites on actin filaments
        
        when a motor neuron sends a signal to a muscle fibre to contract the sarcoplasmic reticulum released calcium ions
        
        the calcium inos bind to troponin (a protein) whcih causes tropomyosin at the sarcomre to move.
        
        exposed binding sites allow myosin heads to bind to actin filaments = causing the contraction of the sarcomere
        
        ATP HYDROLYSIS and cross-bridge formation are necessary for the filaments to slide past eachother
        
        1) atp causes the breaking of the cross bridge by attaching to myosin heads
        2) myosin heads detach from actin fialments
        3) hydrolysis of atp to ADP and a P provides energy for the myosin head to change position (cocked back).
        4) ca2+ ions bind to troponin. troponin causes tropomyosin to move
        5) new cross bridges are formed by the binding of myosin heads to actin binding sites.
        6) energy stored in myosin heads allow it to pull the filaments and contract.
        
        THE SARCOMERE is the functional unit of myofibril in the muscle fibre that contains two protein microfilaments for muscle contractions.
- - - - blood (in the glomerulus) under high pressure caused by difference in diameter of (afferent and efferent) arterioles;
      - fluid plasma and small molecules forced into kidney tubule/Bowman’s capsule/ through fenestrations/basal membrane;
      - which prevent larger molecules/blood cells from passing through;
    - - the basement membrane separates the capillaries
      - there are gaps in the wall of the capillaries called fenestrations
      - smaller projections from the membrane are podocyte food processes, which attach the podocytes (specialised epithelial cells) to the membrane
      - the podocytes function as a barrier through which waste products are filtered from the blood
      - function of glomerulus is to filter the blood passing through it
    - - Fenestrations between the cells in the wall of the capillaries - allow fluid to escape, but not blood cells
      - The basement membrane that covers and supports the wall of the capillaries - it is made of negatively-charged glycoproteins, which form a mesh - it prevents plasma proteins from being filtered out, due to their size and negative charges
      - Podocytes forming the inner wall of the Bowman's capsule - these cells have extensions that wrap around the capillaries of the glomerulus and many short side branches called foot processes - very narrow gaps between the foot processes help prevent small molecules from being filtered out of the blood in the glomerulus
  - - - SODIUM IONS moved by active transport from filtrate to space outside the tubule
      - CHLORIDE IONS attracted from filtrate to space outside the tubule because of charge gradient set up by active transport of sodium ions
      - GLUCOSE AND AMINO ACIDS co-transported out of filtrate and into fluid outside the tubule, by co-transporter proteins in outer membranes of tubules cells
    - - The role of the loop of Henle is to create a solute concentration gradient in the medulla of the kidney.
      - The descending loop of Henle is permeable to water but impermeable to salt ions.
        
        As the filtrate flows down the descending loop (before the ascending loop)water flows out of the filtrate into the interstitial fluid of the medulla by osmosis
        
        As the filtrate flows down the descending loop (before the ascending loop)water flows out of the filtrate into the interstitial fluid of the medulla by osmosis
      - The ascending loop of Henle is permeable to salt ions but impermeable water.
        
        As the filtrate flows up the ascending loop Na+ ions are pumped out of the filtrate into the interstitial fluid of the medulla thus increasing the solute concentration in the medulla.
      - Therefore the medulla has a very high concentration of Na+ ions.
      - The flow of the filtrate in the descending and ascending loop is in opposite directions. This allows for a greater solute concentration gradient to be created in the medulla.
      - The filtrate now leaves the loop of Henle and enters the collecting duct where the water level is fine tuned.
        
        If the solute concentration in the blood is too high, osmoreceptors in the hypothalamus sense this and signal the pituitary gland to produce a hormone called ADH (anti-diuretic hormone).
        
        ADH causes special pores called aquaporins in the collecting duct to open, allowing water to be reabsorbed back into the blood, thus making the blood more dilute. SO ADH INCREASES THE PERMEABILITY OF THE COLLECTING DUCT
        
        If the solute concentration in the blood is too low, osmoreceptors in the hypothalamus sense this and signal the pituitary gland to reduce its production of ADH.
        
        This causes the aquaporins in the collecting duct to close, keeping the excess water in the filtrate, which excreted as dilute urine.
        
        osmoregulation occurs in the collecting duct: Osmoregulation is a form of homeostasis whereby the concentration of blood is kept within a certain range.
        
        The length of the loop of Henle is positively correlated with the need for water conservation in animals
        
        The longer the loop of henle, the more water will be reabsorbed.
        Therefore, animals that live in dry habitats such as the desert have a long loop of Henle. This means the medulla of the kidney is also thicker
        
        The type of nitrogenous waste in animals is correlated with evolutionary history and habitat.
        
        When animals breakdown amino and nucleic acids, nitrogenous waste is formed in the form of ammonia.
        Ammonia is highly basic, toxic and can be very reactive.
        
        Marine and freshwater organisms can release the ammonia directly into the surrounding water.
        
        Terrestrial organisms convert ammonia into a less toxic form (urea or uric acid) before excretion.
        What form depends on the animal's evolutionary history and habitat.
        
        Amphibians release waste AMMONIA AS UREA
        
        Birds and insects release ammonia as URIC ACID. Uric acid does not require water and is highly concentrated. This is beneficial to these organisms as they do not have to carry the extra water around
        
        Mammals release their waste in the less toxic form known as urea
        
        low solute conc in blood = minimal adh (production reduced) = aquaporins close = dilute volume of urine: collecting duct less permeable
        high sol conc in blood = more adh = aquaporins reabsorb water = conc urine (more permeable)
      - Consequences of dehydration and overhydration
        
        DEHYDRATION is the consequence of losing large amounts of water
        
        through excessive sweating, diarrhea, vomiting or urination, without the loss of equal amounts of solutes
        
        The body fluids become hypertonic
        This results in dark coloured urine, lethargy, a raised heart rate and low blood pressure
        
        OVERHYDRATION results when too much water is consumed and the body fluids become hypotonic
        
        drowsiness,
        blurred vision,
        muscle cramps,
        nausea
        
        Treatment of kidney failure by hemodialysis or kidney transplant.
        
        Common causes of kidney failure are diabetes and increased heart rate also obesity
        
        HEMODIALYSIS
        
        Blood is drawn from a vein in the arm and is passed through a dialysis machine for 3 to 4 hours, 3 times per week
        
        As the blood flows through the machine, it passed next to a semi-permeable membrane that contains dialysis fluid (THAT CONTAINS ALL BAD SHIT)
        
        Pores in the membrane allow small particles to diffuse in either direction; however, the pores are too small for plasma proteins and cells to pass through and therefore remain in the blood
        
        ALLOWS FOR:
        
        Urea or waste diffuse from the blood into the fluid
        
        Ideal concentrations of glucose and other metabolites
        
        Excess potassium is extracted out of the blood and calcium is added to the blood
        
        Correct total solute concentration – Allows for excess water to diffuse from the blood
        
        KIDNEY TRANSPLANT as a long-term treatment option for a kidney that is not working properly
        
        A better long term treatment for a kidney that is not working properly is a kidney transplant
        
        Either a living person provides one of their kidneys for transplant or kidneys are removed from someone that has recently died in order to give two kidneys to two individuals
        
        It is essential to have matching blood types and tissue matches to minimize the risk of rejection
        
        The kidney is grafted to the lower abdomen and the renal artery renal vein and ureter are connected to the individual
        
        Blood cells, glucose, proteins and drugs are detected in urinary tests.
        
        Urinalysis is a clinical procedure that examines/analysis urine to detect abnormalities and possible diseases
        
        Blood cells – blood cells in the urine is an indicator of a variety of diseases, including some cancers and infections
        
        Glucose – excess glucose in the urine is almost always an indicator of diabetes
        
        Proteins – Larger amounts of proteins in the urine are an indicator of kidney disease. Small amounts of some hormones such as insulin is normal
        
        Drugs – Many drugs pass from the body into the urine, therefore a urine test can be conducted to detect drug users in sports or for recreational users tested by the police
- - - - 1) germ cells in the fetal ovary divide by mitosis and the cells formed move to distribute themselves through the cortex of the ovary
        2) when the fetus is 5 months old these cells (primary follicles)
        grow and start to divide by meiosis
        3) by the 7th month, they are still in the first division of meiosis and a single layer of cells, called follicle cells, has formed around them
        4) no further development takes place until after puberty
        the cell that has started to divide by meiosis, together with the surrounding follicle cells, is called a primary follicle
        5) during the menstrual cycle a secondary oocyte will be formed
    - - 1) it happens in the testes, which are composed of a mass of narrow tubes, called seminiferous tubules,
        2) the seminiferous tubules are made of cells the outer layer of cells is called the germinal epithelium, with the most mature stages closest to the fluid-filled centre of the seminiferous tubule cells
        3) cells closest to the fluid-filled centre have developed tails and are now spermatozoa
        4) in the wall of the tubule are large nurse cells, called Sertoli cells, which nourish the sperm cells
      - the germinal epithelium cells divide endlessly to produce more diploid cells
        --> diploid cells grow larger and are called primary spermatocytes
        --> each primary spermatocyte divides by the first division of meiosis to produce secondary spermatocyte
        --> in the second division the spermatocyte produce 2 spermatids
        --> spermatids associate with sertoli cells/nurse cells which allow them to develop into spermatozoa (cell differentiation)
    - - The fertilization process occurs within the body of a female is called internal fertilization. (egg protection)
        
        Animals such as mammals have internal fertilization, where embryo develops inside mother, which enhances the protection to the embryo.
        
        Internal fertilization facilitates the survival of the embryo, selective fertilization, and longer protection and minimizes the wastage of gametes.
      - In external fertilization fusion of sperm and egg occurs externally of the female body. External fertilization needs water to facilitate their fertilization, so it occurs in wet environments. Female and male gametes are released to the water, and male gamete is mostly mobile.
        
        Fish and amphibians are examples.
        
        The advantage of external fertilization is that it produces a large number of offspring due to the external hazards.
      - COMPARISON
        
        OUTER SHELL • After the internal fertilization, egg will come out of the body having a thick shell whereas, in external fertilization, eggs are produced with thin tertiary membrane or without membrane .
        
        WATER • External fertilization needs water, whereas internal fertilization does not need water to fertilize.
        
        MOBILITY • Organisms involved in external fertilization have mobile male gametes with flagella, whereas organisms involved in internal fertilization has immobile male gametes.
        
        GAMETES WASTE • In internal fertilization, wastage of gametes is lower, whereas wastage of gametes is higher in external fertilization.
        
        GAMETES NUMBER • Organisms that involved in internal fertilization produce lower number of gametes, whereas organisms involved in external fertilization produce a large number of gametes.
        
        SURVIVAL • Survival of organisms that involved in internal fertilization is higher than the survival of organisms involved in external fertilization.
  - - - After the male and the female gametes combine to form a zygote, the zygote divides by mitosis to form a two-cell embryo.
        
        They two cells grow and replicate their DNA (mitosis) to form a four-cell embryo.
        
        As the embryo is developing, it is moving along the fallopian tube towards the uterus.
      - After continued cell divisions a blastocyst is formed from many cells and is ready for implantation into the endometrium.
      - the blastocyst reaches the uterus after having moved down the fallopian tube --> the outer layer of the blastocyst develops small finger-like projections that allow the blastocyte to penetrate the uterus lining --> blastocyst sinks into the endometrium to obtain a food supply: process called implantation
      - BLASTOCYST a ball of cells that forms early in a pregnancy
    - - The longer the gestation period, the greater the mass size and development at birth.
        
        altricial species are smaller, immature and helpless species.
        
        precocial species are mature, have open eyes at birth, are mobile and are larger.
    - - The male gamete (sperm) is small and motile and only contributes the male’s haploid nucleus to the zygote
      - The female gamete (egg) is large and non-motile and contributes all the organelles and cytoplasm to the zygote
  - - - embryo secretes HCG
      - which acts like pituitary LH,maintaining corpus luteum
      - which produces estrogen and progesterone, maintaining endometrium
      - stimulates growth of placenta
      - inhibits menstruation
      - by second trimester, HCG declines
      - corpus luteum disintegrates
      - placenta produces progesterone/estrogen
      - DETECT presence of HCG
      - can be detected in mother’s urine as a positive test of pregnancy commonly used in pregnancy test kits
    - - The placenta secretes estrogen and progesterone once the hcg levels decline and the corpus leteum deteriorates = it sustains preganancy
      - the placenta is needed because the fetus surface area to volume ratio becomes smaller as the fetus grows larger
        
        placenta is compsed of fetal tissues that is in conatct with the maternal tissue
        
        fetus develops memrbanes that develops the amniotic sac containing the amniotic fluid
      - As maternal blood enters the placenta it leaves the arteries and enters the inter-villous space, where it pools and surrounds the placental villi.
        
        The placental villi are finger-like fetal tissues that have a large surface area for the exchange of materials such as gases, nutrients and wastes.
      - Fetal blood that circulates in capillaries within the villi and microvilli is very close to the surface, allowing for efficient exchange of materials between the fetal and maternal blood.
        
        Materials such as oxygen, nutrients and vitamins diffuse into the fetal capillaries from the maternal blood in the inter-villous space, while carbon dioxide and wastes diffuse out of the fetal capillaries into the inter-villous space.
        
        One umbilical vein carries oxygenated and nutrient rich blood back to the fetus from the placenta.
      - The cells that separate the fetal and maternal blood form a semi-permeable placental barrier. Materials are exchanged between the maternal and the fetal blood in the placenta.
        Note: maternal and fetal blood is never mixed together.
    - - 1) at the end of pregnancy the fetus will secrete hormones that signal the placenta to stop producing progresterone
        (progesterone inhibits the secretion of oxytocin by the pituitary gland).
        2) Oxytocin secreted by the pituitary gland stimulates the muscle fibers in the uterus to begin to contract.
        3) As the muscles in uterus contract, receptors in the uterine wall signal the pituitary to produce more oxytocin.
        POSITIVE FEEDBACK MECHANISM: More oxytocin increases the frequency and intensity of the contractions, thus stimulating the production of even more oxytocin.
        4) Contractions of the muscles of the uterus will cause the amniotic sac to break, releasing the amniotic fluid (This is when the “water breaks” in childbirth).
        5) Relaxation of the muscles in the cervix causes it to dilate, eventually allowing the increasing contractions to push the baby out through the vagina and the cervix.
        6) The placenta is expelled “afterbirth” about 15 minutes after the baby is born.
        
        labor:
        
        progesterone decrease/estrogen increase: triggers formation of oxytocin receptors in uterus
        
        initiate uterine contractions
        
        positive feedback: uterine contractions, via nervous system, stimulate production of oxytocin, a hormone, by posterior pituitary into blood
        
        delivery:
        
        uterine contractions force fetal head against cervix, which dilates
        
        fetal head move through cervix, into vagina, exits
        
        afterbirth: placenta expelled