By N. Roy. Clayton College of Natural Health. 2018.
Francis-West - Chapter 11 Limb Dev (bone not well covered in this textbook) Before we Are Born (5th ed cheap 800mg cialis black overnight delivery. Scleretome has 2 components upper loose (pathway for artery and nerve) and lower compact Vertebra (http://embryology discount cialis black 800mg online. Adult vertebral column 33 total - 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 5 coccygeal Intervertebral Disc Structure - annulus and nucleus pulposus dense region of sclerotome. Chondroblasts in existing cartilage divide and form small groups of cells (isogenous groups) which produce matrix to become separated from each other by a thin partition of matrix. Mesenchymal cells surrounding the cartilage in the deep part of the perichondrium (or the chondrogenic layer) differentiate into chondroblasts. These sutures gradually fuse at different times postnatally, firstly the metopic suture in infancy and the others much later. Osteogenesis Formation of mature osteoblasts - the mesenchymal stem cells initially form preosteoblasts that then differentiate. These cells differentiate first into mitotically active cells, myoblasts, which contain a few myofilaments. Myoblasts undergo frequent divisions and coalesce with the formation of a multinucleated, syncytial muscle fibre or myotube. In the course of the synthesis of the myofilaments/myofibrils, the nuclei are gradually displaced to the periphery of the cell. Skeletal Muscle Stages Myoblast - individual progenitor cells Myotube - multinucleated, but undifferentiated contractile apparatus (sarcomere) Myofibre (myofiber, muscle cell) - multinucleated and differentiated sarcomeres primary myofibres - first-formed myofibres, act as a structural framework upon which myoblasts proliferate, fuse in linear sequence secondary myofibers - second later population of myofibres that form surrounding the primary fibres. The electrical properties of the motor neuron will regulate the contractile properties of all associated myofibres. Each somite pair level gives rise to a group of skeletal muscles supplied by a specific segmental spinal nerve. The muscle arises from a specific somite and the spinal nerve arises from a specific level of the spinal cord (identified by vertebral column). In humans this corresponds to the following spinal nerves (from top to bottom) and muscular functions: C3,4 and 5 supply the diaphragm for breathing. Puberty Musculoskeletal mass doubles by the end of puberty regulated growth by - sex steroid hormones, growth hormone, insulin-like growth factors accumulation of (peak) bone mass during puberty relates to future osteoporosis in old age Abnormalities Additional abnormalities will be covered in the limb development lecture. They have a similar protein structure, with 3 immunoglobulin-like domains in the extracellular region, a single membrane spanning segment, and a cytoplasmic tyrosine kinase domain. The function of the pathway will be to alter the cell directly or indirectly by changing gene expression. Mesoderm outside the embryo and covering the amnion, yolk and chorion sacs is extraembryonic mesoderm. These paired dorsal lateral streaks of cells migrate throughout the embryo and can differentiate into many different cell types(=pluripotential). These cells allow continuous bone remodelling and are also involved in calcium and phosphate metabolism. In the nervous system, it is secreted by the notochord, ventralizes the neural tube, inducing the floor plate and motor neurons. Tbx - T-box genes (transcription factor) involved in mouse forelimb (Tbx4) and hindlimb (Tbx5) specification. The mechanism of Wnt distribution (free diffusion, restricted diffusion and active transport) and all its possible cell receptors are still being determined. Images 2009 Lecture 14 From Embryology Contents Limb Development Introduction This lecture is an introduction to the events in limb development. Initially somites develop and then begin to differentiate forming sclerotome, dermomyotome and then dermatome and myotome. The lateral portion of the hypaxial myotome edge migrates at level of limbs (upper limb first then lower) and mixes with somatic mesoderm. The appendicular skeleton consists of: Shoulder girdle, Upper limb (arm, hand), Pelvic girdle, Lower limb (leg, foot). Limb Axis Formation Four Concepts - much of the work has been carried out using the chicken and more recently the mouse model of development. Axial myoblasts form the myotome Lateral myoblasts migrate to the limb bud (c) Dermotome skin elements (dermis, hypodermis). Origin of limb muscle cells - Migrations traced by grafting cells from a quail embryo into a chick embryo two species very similar in development quail cells recognizable by distinctive nucleoli Quail somite cells substituted for somite cells of 2 day chick embryo wing of chick sectioned a week later found muscle cells in chick wing derive from transplanted quail somites Dorsal/Ventral Muscle Mass Forelimb Muscles Limb Muscle - Differentiation, Skeletal muscle differentiates the same 1. The nephron, the functional unit of the kidney, is also a classical epithelial/mesenchyme type of interaction. The urinary system is developmentally and anatomically associated with genital development, often described as the urogenital system. Adult nephron structure Nephron Development disorganised mesenchymal cells become a highly organised epithelial tubule Condensation - groups of about 100 cells condense tightly together to form a distinct mass Epithelialisation - condensed cells lose their mesenchymal character and gain epithelial At end of this period formed a small epithelial cyst complete with a basement membrane, cell-cell junctions and a defined cellular apico- basal polarity. Bladder Structure Can be described anatomically by its 4 layers from outside inward: Can be described anatomically by its 4 layers from outside inward: Serous - the superior or abdominal surfaces and the lateral" surfaces of the bladder are covered by visceral peritoneum, the serous membrane (serosa) of the abdominal cavity, consisting of mesthelium and elastic fibrous connective tissue. Detrusor Muscle The adult detrusor muscle consists of three layers of smooth Bladder histology (involuntary) muscle fibres. Anatomically can be described in two parts the abdominal part (pars abdominalis) and pelvic part (pars pelvina). The ureter is composed of three layers: outer fibrous layer (tunica adventitia), muscular layer (tunica muscularis) and mucous layer (tunica mucosa). The muscular layer can also be subdivided into 3 fibre layers: an external longitudinal, a middle circular, and an internal longitudinal. During migration from the sacral region the two metanephric blastemas can come into contact, mainly at the lower pole.
The pituitary gland under the brain sends signals to the ovaries to increase or decrease sex hormone (oestrogen) production buy cialis black 800 mg with visa. A tumour or cancer of the pituitary gland or ovaries may result in excessive hormone levels and breast milk production 800mg cialis black free shipping. Other causes of an abnormal nipple discharge include breast cancer that involves the milk ducts (brown or blood stained discharge), kidney failure (may prevent the excretion of the normal amount of oestrogen and the levels of hormone increase), under or over active thyroid gland (hypothyroidism and hyperthyroidism), Cushing syndrome (over production of steroids, or taking large doses of cortisone) and excessive stimulation of a woman’s nipples for a prolonged period of time may result in a reflex which increases oestrogen levels and results in milk production. Examples include methyldopa and reserpine (used for serious high blood pressure) and tricyclic antidepressants. If a woman intends to breastfeed, the doctor will examine the breasts during an antenatal visit, and if the nipples are flat or inverted, a nipple shield may be worn to correct the problem. The shield fits over the nipple drawing it out gently, making it protrude enough for the baby to feed. Stimulating the nipple by rolling it between finger and thumb, and exposing the breasts to fresh air (but not direct sunlight) may also help. It is a shallow dish shape, has a tab handle on one edge and a hole in the centre through which the nipple partly protrudes. A nuchal translucency scan is a form of ultrasound scan that measures the amount of fluid in the nuchal cord in the neck of a foetus between weeks 11 and 14 of pregnancy. An abnormal result indicates a higher risk of the foetus having Down syndrome or other spinal cord defects (eg. It is usually combined with a blood test (triple tests) to measure hormone levels that may also be abnormal in women with a Down syndrome pregnancy. These tests are only indicative and an amniocentesis or chorionic villus sampling is necessary to confirm the diagnosis. Unfortunately, if an abnormality is found, there is no treatment available for the foetus, but the mother is given the option of an abortion. They consist of a pair of blades with handles at one end for the doctor to grip, an open cup shape at the other end to encompass the baby’s head and a joint in the middle that enables the forceps to be either manipulated together or separated. They come in many shapes and sizes depending on their purpose, the size of the baby, how far the baby has progressed through the birth canal and the position of the head. Wrigley obstetric forceps are the smallest, and most commonly used as an aid to lift out the head in the very last stage of labour. This fluid acts to protect the foetus from bumps and jarring, recirculates waste, and acts as a fluid for the baby to drink. It may be caused by abnormal development of the foetus, or abnormal function of the placenta, but in most cases, there is no reason for the problem. The condition is diagnosed by an ultrasound scan, and if proved, further investigations to determine the cause of the condition follow. All the eggs (ova) a woman will ever have - and considerably more than she will ever need - are contained in her ovaries when she is born. By puberty these are reduced to about 300,000, and only about 400 will be released during the childbearing years. The number of ova in the ovaries steadily decreases during middle life, and at by the time menopause starts only 25,000 are left. The ovum (egg) is the largest single cell in the body, but still needs a powerful microscope to be seen. When puberty is reached, a cycle is established in which a few of the egg cells develop each month, with one reaching full maturity. A woman is fertile and can become pregnant a day or two either side of ovulation - and not at other times. When an egg is released, it is swept into the adjacent Fallopian tube, the other end of which connects with the uterus. It is this hormone that causes the lining of the uterus to thicken and the body to prepare for pregnancy. When the egg is released, the production of the second hormone, progesterone, increases, preparing the lining (endometrium) still further and bringing it to total readiness for a fertilised egg. If there is no conception, the oestrogen and progesterone levels fall suddenly and the uterine lining is shed during menstruation. It is the female hormones that also give a woman her secondary sexual characteristics, for instance her broader hips than the male, her breasts, pubic and armpit hair, and her rounder, more feminine shape. This test is more reliable than the usually performed lecithin- sphingomyelin ratio in diabetic mothers. As the foetus grows, it floats in a fluid-filled sac like a water-filled balloon (the amniotic sac), and the foetus drinks the amniotic fluid and excretes into it through the kidneys. The amniotic sac and its fluid act as a very effective shock absorber so that the foetus can survive unharmed quite serious injuries to its mother (eg. One side of the sac is especially modified into the placenta, while the rest is a fine but tough transparent membrane. The foetus is connected to the placenta by the umbilical cord, which contains three intertwined blood vessels (a vein and two arteries), which convey nourishment from the mother to the foetus and waste products the other way. Doctors will check the cord after birth, and if only one vein is present instead of two, it is probable that the baby will have some hidden birth defect. Infections (particularly viruses such as German measles) may also pass to the foetus through the placenta. Several minutes after the birth, the placenta (the afterbirth) is expelled by further contractions of the uterus, assisted by gentle traction on the cord by the doctor or midwife. This complication of pregnancy is more common in women who have had a previous caesarean section as the placenta tends to attaches abnormally to the caesarean scar in the uterus. Abruption may be caused by high blood pressure in the mother, or injury to the mother, but in the vast majority of cases, no specific cause can be found.
Excitable Tissue: Tissue capable of producing electrical signals when excited includes muscle and nerve cialis black 800mg amex. Feed forward mechanism: a response designed to prevent an anticipated change in a controlled variable cheap 800 mg cialis black with visa. Fibrinogen: soluble plasma protein that is changed to thread like molecules that form the blood clot. First messenger: an extracellular chemical messenger that binds with the membrane receptor and activates an intracellular second messenger to achieve desired cellular response. Frank-Starling law of the heart: intrinsic control of the heart, such that increased venous return resulting in increased end-diastolic volume leads to an increased strength of contraction and increased stroke volume; that is, the heart normally pumps out all of the blood returned to it. Golgi complex: a cellular organelle that processes raw materials into finished product and sorts and directs for final destination. Granulocytes: Leukocytes that contain granules such as neutrophils, eosinophils and basophils. Helper T- cells: T- cells enhancing the activity of other immune response effector cells. Hyperpolarization: an increase in membrane potential from resting potential, becoming even more negative. Internal environment: The body extracellular fluid region having plasma and interstitial fluid. Left ventricle: the heart chamber that pumps blood in to the systematic circulation. Lysosome: Cell organelles having powerful hydrolytic enzymes that destroy unwanted material within the cell. Macrophage: large tissue bound phagocytic cells Mean arterial blood pressure: the pressure responsible for driving blood forward through the arteries in to the tissues throughout the cardiac cycle. Motor neurons: neurons that innervate skeletal muscles Motor unit: is motor nerve plus all of the muscle fibers innervated. Multi-unit smooth muscle: muscle with multiple discrete cells independent of each other Myelinated fiber: neuronal axon covered at regular intervals with insulative myelin. Negative feed: a regulatory mechanism in which a change in the controlled variable triggers a response that opposes the change, thus maintaining a steady state of the variable. Paracrine: a local chemical messenger exerting effects only on nearby cells in the immediate vicinity of secretion. Phagocytosis: a type of endocytosis Plaque: a deposit of cholesterol and other lipids, perhaps calcified, in the thickened, abnormal smooth muscle with in blood vessels as a result of altherosclersis. Positive feedback: a regulatory mechanism in which the inputs and outputs in control system continue to enhance each other so that the variable moves further from steady state value. Purkinje fibers: Small terminal fibers that extend from the bundle of it is and rapidly transmit an action potential throughout the ventricular myocardium. Refractory period: Period when an activated membrane is refractory to further stimulation preventing action potential from spreading backward. Right atrium: the heart chamber that receive venous blood from the systemic circulation. Right Ventricle: the heart chamber that pumps blood in to the pulmonary circulation. Saltatory condition: propagation of action potential in a myelinated fiber with the impulse jumping from one node of Ranvier to another. Sarcoplasmic reticulum: reservoir of ionic calcium Second messenger: an intracellular chemical messenger activated by extracellular chemical that triggers preprogramed biochemical events, resulting in control of cellular activity. Signal transduction: The sequence of events, which carry signals from first chemical messenger conveyed to the cell. Vasoconstriction: the narrowing of a blood vessel lumen as a result of contraction of the vascular circular smooth muscle. Vasodilatation: the enlargement of a blood vessel lumen as a result of relaxation of the vascular circular smooth muscle. Venous return: the volume of blood returned to each atrium per minute from the veins. After this chapter the student is expected to: • relate the structural organization of the respiratory system to its function • describe the functional importance of the intraplueral fluid , the parietal and visceral pleura • know the structural and functional features that distinguish the respiratory zone of the airways from the conducting zone • define and describe the alveolar-capillary unit • know the definitions fractional concentrations (of dry gas) and partial pressure of gases • know the normal values of partial pressure of oxygen and carbondioxide in arterial and mixed venous blood • know how exchange of gases occur between the blood and tissues • know the control mechanisms involved in respiration Introduction The major functions of the respiratory system can be divided in two categories: respiratory and non-respiratory. The respiratory system must obtain oxygen from the environment and must eliminate carbondioxide produced by cellular metabolism. These processes must be coordinated so that the demand for oxygen is met and so that the carbondioxide that is produced is eliminated. The respiratory system is well designed to carry out gas exchange in an expeditious manner. It participates in + maintaining acid-base balance, since increase in Co2 in the body lead to increased H the lungs also metabolize naturally occurring compounds such as angiotensin I, 229 prostaglandins and epinephrine. Functional anatomy of the respiratory system Functionally, the respiratory air passages are divided into two zones: a conductive zone and a respiratory zone. The airway tree consists of a series of highly branched hollow tubes thatdecrease in diameter and become more numerous at each branching. Trachea, the main airwayin turn branches into two bronchi, one of which enters each lung. Within each lung, these bronchi branch many times into progressively smaller bronchi, which in turn branch into terminal bronchioles analogous to twigs of a tree. The terminal bronchioles redivide to form respiratory bronchioles, which end as alveoli, analogous to leaves on a tree.
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