HUBS191 Lecture Notes PDF

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HUBS191 SUMMARY NOTES 2018Lecture 1: Introduction to HUBS 191Understand the special considerations of the Human Tissue Act (2008) and how they affect you.1. Voluntary donation of bodies2. Deceased person’s wishes can be overridden by objections of surviving spouse or relative3. No reference to how l...

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HUBS191 SUMMARY NOTES 2018

Lecture 1: Introduction to HUBS 191 Understand the special considerations of the Human Tissue Act (2008) and how they affect you. 1. Voluntary donation of bodies 2. Deceased person’s wishes can be overridden by objections of surviving spouse or relative 3. No reference to how long we can keep body parts 4. Avoid unnecessary mutilation of body – show respect. Consider the levels of organization that contribute to the human body.  Body  System – functionally related group of organs that are working together  Organ – collection of tissues  Tissue – composite of similar cells specialized by function  Cell  Organelles – tiny organ that aids functioning of cell  Molecular and atomic Describe the four basic types of tissue in the human body.  Tissues consist of specialized cells embedded within an extracellular matrix  They differ in the type of material making up ECM – water, proteins, collagen (strong), elastin (more elastic tissue), proteoglycans (firmness, structure and shape)  The way a tissue behaves depends on its constituents Epithelial  [Thin] layers/sheets of cells, v/ little matrix  Covers/protects body surfaces, lines cavities  E.g. skin, lining of tracts, glands (make hormones) Connective  (Where a strong and elastic structure is required)  Sparse cells, lots of matrix containing fibres  Supports structures, transports substances  E.g. bones, cartilage/tendons, fat, blood Muscle  Long fibre-like cells, strong fibres capable of pulling loads  Produces movement and heat (keeps us warm when cold)  Muscles: skeletal (attached to skeleton), smooth, cardiac Nervous  Highly cellular of many types, conducting and supporting  Communication and coordination between body arts  E.g. nerves, sensory organs, brain and spinal cord  Most diverse tissue  Conducting electricity in nervous system

Lecture 2: Homeostatic Principles: The importance of the internal environment and the concept of homeostasis.

Define ‘homeostasis’ and explain why extracellular fluid (ECF) composition is regulated in multicellular organisms.  Homeostasis = the maintenance of relatively constant conditions in the internal environment (ECF) in the face of external (or internal) change – so external environment less critical for multicellular organisms, allowing them to thrive in a variety of conditions. (External environment = threats and opportunities).  In our body there are mechanisms to maintain constancy, and any tendency towards change is automatically met with factors that resist change – there are co-operating mechanisms which act simultaneously or successively to maintain homeostasis.   Intracellular fluid (ICF) = fluid inside cells = 2/3 of total body water  Extracellular fluid (ECF) = cells immediate environment = 1/3 of total body water – supplies correct temp., pH, route for nutrient delivery & waste disposal etc. - 4/5 of ECF surrounds individual body cells as interstitial fluid (ISF) - 1/5 of ECF comprises plasma (non-cellular component of blood) – in blood vessels - ECF also includes various transcellular fluids inside epithelial-lined spaces, e.g. synovial fluid, ocular fluid, cerebrospinal fluid. Understand the importance of regulating selected ECF variables and be able to state their normal reference ranges. Sodium (Na+) = main extracellular cation  Largely determines ECF volume (so influences blood pressure)  Important in action potential generation in nerve and muscle tissue  Normal ECF concentration = 135-145 mmol/L Calcium (Ca++)  Important structural component of bones and teeth  Involved in neurotransmission and muscle contraction  Essential for blood clotting  Regulates enzyme function  Normal plasma concentration = 2.2 – 2.6 mmol/L - number would differ if total Ca++ ECF conc. Measured, but Ca++ can’t enter ISF very easily, so usually just plasma concentration is measured. Glucose = used by cells (especially neurons) to produce ATP (neurons affected significantly by low glucose levels)  Normal fasting concentration = 3.5 – 6 mmol/L  Non-fasting (random) = 3.5 – 8 mmol/L  Hypoglycaemia usually caused by too much insulin being administered manually. Potassium (K+) = most abundant intracellular cation  Main determinant of resting membrane potential (and very important in excitable tissue)  Normal concentration in ECF = 3.5 – 5 mmol/L pH – normal pH of ECF = 7.35-7.45  Less than this = acidosis = decreased neuronal function and loss of consciousness  More than this = alkalosis = ‘over-excitability’ of nerve and muscle – ‘pins and needles’, muscle spasms, convulsions Core body temperature = 36 – 37.5OC for optimal metabolic and physiological functioning.  Oral & axillary temperatures are usually about 0.5OC less than rectal (core)  Peripheral temperature is more variable – if our skin vets cooler for a while, it doesn’t matter, but if our organs cool down, we die.  Important because: at high temps proteins start to denature, at lower temps chemical reactions slow down, preventing normal cell function.  As cells of the nervous system become compromised, ability to thermoregulate is lost  rapid worsening of the initial condition and accelerated movement of temperature away from normal, leading towards death = viscous cycle = detrimental positive feedback loop. Outline selected transport mechanisms across cell membranes. Diffusion = Net movement from area of high concentration to low concentration until the substance is equally distributed over the whole area – rapid over short distances within cells and between cells and capillaries (usually this is less than 50 micrometers) - cells in cartilage/tendons are further away from blood vessels, so these areas take longer to heal when injured.

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Some substances are able to diffuse directly through lipid bilayer down their concentration gradient – lipid soluble gases (oxygen + carbon dioxide), steroid hormone (based on cholesterol = lipid, so can dissolve in membrane), anaesthetic agents (have to be able to cross blood brain barrier, so need to be lipid soluble).  Passive process – no energy input required.  A particle won't cross the membrane via diffusion if it's not lipid soluble, it has a high electrical charge or it's very big. Simple diffusion via membrane channels = Channels are usually specific and may be open/closed spontaneously (leak channels) or in response to various stimuli, e.g. chemicals (ligand gated) or change in membrane potential (voltage gated).  Water diffuses through protein channels = aquaporins.  Specific channels for many ions – K+, Na+, Ca++ (electrical charge makes it difficult to diffuse across the membrane) Carrier mediated passive transport (= facilitated diffusion) = Substance binds to carrier in one side of membrane, inducing carrier to change shape and release substance to other side (down concentration gradient).  a carrier is not the same as a channel.  E.g. glucose entry into cells when insulin is present. Primary active transport = Energy from hydrolysis of ATP used to move substances against their concentration gradient.  E.g. sodium-potassium pump – moves 3 Na+ out and 2 K+ in (uses 1 ATP each time) – maintains ionic gradients & helps regulate cell volume – more Na+ on outside of cell than inside, so cell needs to use this process to move Na+ out. Exocytosis and endocytosis = substances transported in or out of cell in membranous vesicles.  E.g. secretion of insulation by beta cells of pancreas (exocytosis)  E.g. phagocytosis of microbes by neutrophils (endocytosis) Define ‘osmosis’, ‘osmolarity’ and ‘tonicity’ and understand their relevance to cell volume. Osmosis = the net movement of water across a membrane down its own concentration gradient (towards the region of higher solute concentration) – differences in solute concentration across cell membranes can cause fluid shifts and create pressure that can damage cells. Pressure required to stop osmosis = osmotic pressure. Osmolarity = a measure of the total number of solute particles per litre of solution. Units = osmol/L or mosmol/L. Normally 275-300 mosmol/L in ECF and ICF.  If osmolarity of one compartment changes then water will diffuse via osmosis until equilibrium has been restored.  E.g. intravenous distilled water would ‘dilute’ the plasma and cause water to move into the interstitial compartment, then the intracellular fluid until equilibrium is reached – causing net water movement into the cell – it will swell and eventually burst. Tonicity = refers to the effect that a solution has on cell volume. - HYPERtonic solutions cause cell to SHRINK - HYPOtonic solutions cause cells to SWELL - ISOtonic solutions cause NO CHANGE in cell volume  If we're infusing fluids into bodies, we need to think about the tonicity of those solutions – clinical solutions shouldn’t produce unwanted fluid shifts. Note: Osmolarity is a property of a particular solution (independent of any membrane), while tonicity is a property of a solution with reference to a specific membrane. Note: a 300 mmol/L solution of urea has approx. the same concentration of solute particles as our body fluids (isosmotic), but isn’t isotonic because urea can enter blood cells easily via specific urea transport molecules in the cell membrane and there’s normally a low urea concentration inside the cell. 

If concentration of solutes on either side of the membrane is similar and they cannot easily cross the cell membrane then there is no osmotic gradient for net water diffusion and cell volume will remain unchanged  solution is isosmotic and isotonic.

Lecture 3: Homeostatic Control: Physiological control systems

Understand the basis of the cell’s ‘resting membrane potential’ and appreciate its physiological significance. Resting membrane potential (RMP): inside of cell membrane is negatively charged compared to its external surface – magnitude of this negativity is typically about -70mV (millivolts) (if the outside of the membrane is taken as zero mV)  RMP results from the separation of a small number (just a few needed) of oppositely charged ions across the lipid bilayer – overall concentrations of ions in the ICF and ECF aren’t significantly affected.  RMP is due to different concentrations of ions across the membrane and their respective permeabilities to it.  Cell membrane normally much more permeable to K+ than other ions, so K+ is the major determinant of the RMP. Define ‘regulated variable’, ‘set point’ and ‘reference range’.  Regulated variable (controlled variable) = the variable that our system senses and tries to keep stable  Set point = target value for that variable  Reference (normal) range = values of the regulated variable within acceptable limits. Explain why there is variability in controlled variable values between individuals and within individuals.  There is variation in regulated variables within and between ‘normal’ people (intra and inter individual variation)  For most physiological variables, body cells are healthy over a range of variables.  Within that Describe how negative feedback and feed-forward control systems operate to achieve homeostasis. Negative feedback (the most important types of feedback for physiological control) systems oppose the change in the regulated variable and move it back towards the set-point. Key components: 1. sensor 2. integrator 3. effector 4. communication pathways Physiological control pathways: NEURONAL HORMONAL

Lecture 4: Anatomical terms Explain the Anatomical Position.

Feed-forward = detection/anticipation of external or internal conditions or situations that could alter a regulated variable (disrupt homeostasis) if some sort of PREMPTIVE action was not taken  Why we feel cold before internal temperature decreases if external temp decreases.  Integration center establishes a future ‘predicted value’ for the regulated variable, compares this with the ‘set-point’ ad makes anticipatory corrections (if body doesn’t respond, temperature will drop)  E.g. Goosebumps and shivering when you enter a cold environment (physiological feed-forward), putting on more clothes/ seeking warm shelter/turning on heater if skin feels cold (behavioural feed-forward), putting on more clothes if it look scold outside (behavioural feedforward) Describe the physiological control systems for thermoregulation.  Radiation  Conduction  Convection  evaporation Define ‘positive feedback’ and outline a physiological example. Positive feedback = a response to a stimulus that moves the controlled variable even further away from the set-point (it reinforces the initial change).  Not common physiologically, often detrimental  Can be destabilizing and result in ‘vicious cycles’.  Can be useful in physiological situations where there’s a specific endpoint or purpose, e.g. childbirth and blood clotting. Childbirth example: Uterus contracts, pushes head of baby into birth canal, against cervix – stretch (variable) detected (by sensor), hypothalamus (integrator) alerted, so the pituitary gland (effector) is stimulated to release oxytocin, which increases contraction strength, which pushes baby's head further into birth canal etc. - this is positive feedback, but it will stop when the baby is out, so there's a specific endpoint. Blood clotting: Platelets will start sticking, then these attract a whole lot more - there's a snowball effect. The end point is sealing up artery and stopping blood loss, but if you can't switch off this process, then you have enough clotting factor in your body to clog up the entire vascular system in a few minutes - so this positive feedback cycle needs to be controlled very carefully.

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Upright Face forwards Feet together, toes pointing forwards Palms facing forwards Static

Define the terms used to describe spatial and positional relationships of human anatomy.  Superior = closer to head  Inferior = closer to feet  Anterior = closer to front  Posterior = closer to back  Medial = closer to midline (mid-sagittal plane)  Lateral = further from midline (mid-sagittal plane)  Proximal = closer to trunk (used in limbs only – in appendicular skeleton)  Distal = further from trunk (used in limbs only)  Deep = further from the surface  Superficial = closer to the surface  Sagittal plane = divides the body into left and right portions  Coronal plane = divides the body into anterior and posterior portions  Transverse plane = divides the body into superior and inferior portions Define and demonstrate terms of movements as related to joints.  Flexion = when angle decreases at a joint (fleshy parts of limb brought closer together)  Extension = when angle increases at a joint (moving fleshy parts away)  Dorsiflexion = toes brought up towards face (occurs at the ankle joint, in the sagittal plane)  Plantarflexion = toes pointing down towards the ground (occurs at the ankle joint, in the sagittal plane) - Plantarflexion & dorsiflexion are important movements for stabilizing the ankle joint while walking.  Abduction = movement at joint moving limb away from midline E.g. of the hip, shoulder  Adduction = movement at joint bringing limb towards midline  Circumduction = combination of flexion/abduction/extension/adduction (combination of angular movements) – NO ROTATION E.g. Wrist can circumduct but can’t rotate (as the joint isn’t round, it’s oval)  Rotation = rotation around the long axis of a joint (no change in angle so not circumduction) – can be lateral (away from midline) or medial (towards midline) E.g. sideways rotation of head – bony arrangement between axis and atlas allows rotation around the long axis through the neck only. Humerus has a round head, allowing us to rotate our upper limb laterally and medially.  Pronation = palm faces posterior (rotates radius over ulna)  Supination = palm faces anterior, forearm bones parallel  Inversion = sole of foot faces towards midline (occurs only at the ankle joint, where the tibia, fibula and tarsals meet).  Eversion = sole of foot turns away from midline (occurs only at the ankle joint, where the tibia, fibula and tarsals meet). HUBS Lab 1:  Opposition = movement of thumb to touch

Lecture 5: Bones - Structure of the Skeleton Describe the functions of the skeletal system.  Support = have hard tissues inside that support us and hold us upright.  Movement = Muscles are attached to bones by tendons, which move those bones when muscles contract.

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Protection = e.g. the cranial vault - bones wrap around the brain, protecting it & supporting it from underneath. Storage = e.g. for calcium; this is then drawn on by the rest of the body to maintain homeostasis. RBC formation = RBCs are formed inside bones, in the bone marrow. In children, all bones are filled with red bone marrow, but once finished growing, red marrow is only found at the ends of long bones and in the bones of the vertebral column. Blood cell formation = haemopoeisis.

Describe the gross structure of bones and explain how they reflect their functions.  Compact and cancellous bone is made of the same extracellular and intracellular materials, but have a different structure at the gross level due to their different function. Compact bone  Strength and load-bearing Cancellous/spongy bone  Shock absorption - Long bones = longer than they are wide; shaft/diaphysis + epiphyses; function as levers for movement. Thicker compact bone in diaphysis, cancellous bone inside epiphyses (surrounded by a thin shell of compact bone) - Short bones = near equal in width and length; weight bearing/shock absorption; mostly cancellous bone - Flat bones = mostly flat; protection – e.g. cranial bones; muscle attachment (scapula); thin plates of compact bone – some cancellous. - Irregular bones = variable shape and function (vertebrae – mostly cancellous, but have projections of compact on posterior side) Describe the structure of the human skeleton and explain how the structure reflects its function. Axial skeleton = central core of body – limbs move around axis.  Skull = cranium + facial bones + mandible  Vertebral column; vertebrae become wider in inferior direction as more shock absorption and weight bearing is required at the bottom of the spinal cord (needed for our function = bipedal locomotion). Cervical (7) = form the neck – most mobile region of column – needed so we can rotate heads. Thoracic (12) = where ribs join to form rib cage (12 ribs) – small, incremental movements can occur between these vertebrae Lumbar (5) = most inferior part of vertebral column – more movement here to help with movement s during locomotion – many stresses in the lumbar region because of this, so many lower back injuries in humans. Sacrum and coccyx – sacrum = 5 separate sacral vertebrae in children, which fuse during teen years.  Rib cage = ribs + sternum – rib cage moves as we breathe. Appendicular Skeleton = limbs (appendages) – these join onto the axial skeleton  Ulna has a hook-shaped epiphysis at the proximal end, Regions: which meets with humerus to form a very stable joint, but  Arm (humerus) – between shoulder and elbow has a round head at the distal end, which allows rotation of  Forearm (radius + ulna) – between elbow and wrist the radius around the ulna, for pronation and supination.  Thigh (femur) – between hip and knee  Leg (tibia + fibula) – between knee ad ankle Long Bones: Head of femur much more round than head of the Limb structure: humerus = way that the bones meet at the hip joint  1 proximal long bone – humerus/femur (very stable) is different to the way the flatter head of  2 distal long bones – radius + ulna/ tibia (medial) + fibula the humerus meets the scapula to form the shoulder (lateral) - radius can rotate around ulna, but tibia and fibula can’t do this as we want stability in our legs. joint.  Most stability at shoulder joint (rotator cuff) is provided  Hands (8 carpals, 5 metacarpals, 3 phalanges in each by muscles, whereas stability at hip provided by the finger, 2 phalanges in thumb) shape of the femoral head.  Feet (7 tarsals, 5 metatarsals, 3 phalanges in each toe, 2 phalanges in big toe) – overall function is to form one  Both have long diaphysis, and round heads at the big level for locomot...