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Calcium homeostasis

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Calcium plays a structural role in the body as a component of bones and teeth but also as a biological trigger with roles in enzyme stimulation, neurotransmitter release, exocrine and endocrine simulation, muscle contraction, heartbeat, blood clotting. Homeostasis aims to closely regulate the plasma concentration of Ca2+ at 2.25-2.75mmol/L and intracellular concentration of 0.1micromol/L (10^-7M). Regulation involves antagonistic hormones: parathyroid hormone (which stimulates ca2+ absorption), calcitonin (reduces osteoclastic activity and reduces reabsorption of intestinal calcium) as well as activated vitamin D3 (important in intestinal calcium absorption). Extracellular calcium balance is regulated with hormones affecting intestinal absorption and excretion, kidney reabsorption and excretion and bone deposition and resorption. Cellular concentration is regulated by exchanging calcium with the extracellular fluid (Figure 1). body calcium is 1% in ICF, 0.1% in ECF and 99% in bone

Introduction to the endocrine system

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The endocrine system refers to the collection of glands that produce hormones that regulate bodily functions. The neuroendocrine system is how neural tissues (hypothalamus) communicates with the endocrine system to regulate homeostasis. Hormones are chemical products released in small quantities into the blood stream to exert effects on target organs. It is a form of extrinsic homeostatic control. Different organs and glands are responsible for releasing specific hormones which serve a specific function (Figure 1). Hormone release is regulated by neural mechanisms (hypothalamus, autonomic nervous system), releasing hormones (i.e hormones released by the pituitary gland that trigger release of hormones in a distant gland), direct or indirect regulation by nutrient or ion ( e.g glucose triggering insulin production, plasma Ca2+, PO4- and parathyroid hormone). Figure 1 The hypothalamus is a small region in the centre of the brain below the thalamus and near the pituitary gland. Th

Fluid compartments and sodium balance

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The human body derives support and nourishment from the external environment but its function is relatively independent of it. This independence comes from the fact that the tissues are contained from the external environment and is constituted by a separate internal environment that consists mainly of fluids circulating the body. 60% of the body is composed of fluids much of which are extracellular fluids (interstitial fluids and vascular fluid). Vascular fluid refers to the fluid portion of blood i.e blood plasma. Interstitial fluids are the fluids that surround the cells of the body which is filtered from Vascular fluid through capillaries. It brings nutrients to cells and drains waste products from them towards lymph vessels. Most cells are within 50 microns of a capillary which ensures rapid diffusion of nutrients from circulation to interstitial fluid to cells and vice versa. ECF is in  intimate contact with 4 organs that interface with external environment: alimentary canal, 

Introduction to homeostasis

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Homeostasis is the maintenance of stable conditions in the internal environment. The internal environment is constantly disturbed by stress (stimuli that imbalances the internal environment). This stress can be external (heat, cold, lack of oxygen) or internal (pain, tumours). Control systems are in place to keep the physical and chemical state of the aqueous internal environment constant. Organ homeostatic control systems can be intrinsic/local (e.g autoregulation of tissue blood flow) or extrinsic/distant (e.g ANS, hormonal signalling). A breakdown in homeostasis is a feature of many disease states. Consider the balance of an organism as a see-saw and stresses as destabilising elements. In general, phyisological control systems will use receptors/sensor to detect an imbalance of a variable, send information down an afferent pathway to the control center which will process this signal and sent efferent  signals to the effector that will feedback to influence the magnitude of stimu

Physiology

Phyisology is the branch of biology dealing with normal function of the body. The lectures in the primary orientation will deal with these functions by exploring the various systems that underlie daily function of the human body. An understanding of phyisology is essential to understand the other subjects of pathology and pharmacology. Pathology will explore what happens when these systems break down and pharmacology will explore the medications that target the physiological systems of the body. An understanding of cell biology and biochemistry will explore the body at a cellular and subcellular level and you will see how these contribute to the larger functions of the body. The lectures in order are as follows: Homeostasis Sensation and local anaesthetic Pain Masticatory muscles Mastication Autonomic and enteric nervous systems Saliva Respiration The cardiovascular system

First post!

So I've been working on Dental Tidbits for a while and I'm entering a different stage in my career. I've signed up for the RACDS primary orientation course this year and I've just received a copy of the lecture notes. To be honest a lot of it looks like uni stuff (which i've long forgotten) but there is a fair amount of content to churn through. I do get the sense that supplemental texts will be very important to consolidate and extend knowledge from the lecture notes and I'm not sure how i'm going to manage to get my hands on them. I'm actually quite proud of the fact that I bought no textbooks over the course of my 5 year degree. I know that there will be copies of the text books in the ADA NSW library but this is a fair inconvenience to travel interstate for this. There may be some "non legal" copies on line that I may have to access or maybe some copies in the medical university libraries in Brisbane which is also a bit of a trek. Anywa