Week 1

Week 1

1. What are we made of?

   • Biomedical Sciences
     • anatomy - body structure
     • pharamcology - drugs and their actions
     • physiology - body functions
     • neuroscience - nervous system functions
     • biochemistry - chemistry involved in life
     • cell biolofy - how cells work
     • microbiology - microbes and their effects and treatments
     • nutrition - diet and health effects
     • pathology - what happens in disease
     • psychology/psychiatry - ab/normal mental function
   • Physists' Answer
     • percent by mass of each element present in the body
   • Biochemists' Answer
     • water - 60%
     • fat - men, 13-17%; women, 20-21%
     • proteins - 15%
     • rock - 10%
     • salts - 0.5%
   • Cell Biologists' Answer
     • cell organelles
     • membrane
     • nucleus
   • A Set of Tissues
     • epithelia
       • cover surfaces
       • form interfaces
       • absorption and secretion
     • muscle
       • contractile
       • movement
     • connective
       • package and divide
       • support
       • energy storage
       • space filling
     • neural
       • excitable cells
       • sensory and motor
       • transmit signals
       • process incoming information
   • Set of Regions
     • head and neck
     • thorax
     • abdomen
     • pelvis
     • upper limb
     • lower limb
   • Set of Systems
   • Body Fluid Compartments
     • total mass - 70kg
     • total body water - 42 L
       • intracellular fluid - 28 L
       • extracellular fluid - 14 L
         • plasma - 3.5 L
         • extravascular fluid - 10.5 L
     • highest concentrations in fluids
       • plasma - Na & Cl
       • interstitial - Na & Cl
       • intracellular - K & HPO4

2. Cell Biology

   • Membranes
     • separate 2 areas that need different conditions
     • phospholipid bilayer
     • phospholipids
       • polar head - charge effects whether it is hydrophobic or philic
       • fatty acid tail(s)
       • single tail - micelle
       • 2 tails - bilayer
     • triglycerides
       • glycerol backbone
       • 3 fatty acids
       • fatty acids can be saturated or unsaturated
       • unsaturated - bends in chain, fixed
       • saturated - floppy and straight
     • diglycerides
       • 2 fatty acids
       • third attachment is a phosphate attached to choline for example
     • cholesterol
       • stiffens backbone
       • planar fixed
       • changes membrane properties
     • carbohydrates act as signals to passing molecules
   • Energy
     • 3/4 of all energy used to pump K/Na in and out of cells
     • active transport - pumps against concentration gradient
     • cotransport
       • a substance in pumped in or out and by doing so all moves another molecule in or out
     • passive diffusion - doesn't require energy, goes down a cencentration gradient
     • pumps are proteins
   • Endosymbiotic Hypothesis
     • the arrival of eukaryotes
     • evidence
       • double membranes on mitochondria
       • mitochondria division isn't controlled by the cell
       • mitochondria have their own DNA
   • Nucleus
     • DNA storage
     • DNA synthesis
     • transcription
     • nuclear pores - allow molecules/DNA in and out
   • ER
     • synthesis or the membrane
     • synthesis of secretory proteins
   • Ribosomes
     • protein synthesis
     • attach to the ER via translocator complexes
   • Golgi Apparatus
     • packaging of molecules
   • Protein Movement
     • signals sticking into cytoplasm
     • package into vesicles with targetting signals on
     • send everywhere are retrieve from where it isn't used
     • motor proteins on cytoskeleton
   • Cytoskeleton
     • microfilaments - actin, cell periphery, microvilli
     • microtubules - tubulin, structural support, vesicle transport, form cilia, subcellular organisation
     • intermediate filaments - insoluble protein network, nuclei contain their own intermediate filaments (Lamins)
   • Proteasome
     • protein binds with polyubiquitin chain
     • protein then passes through preasome
     • protein broken down
   • Lysosome
     • breakdown of damaged organelles to be secreted
     • breakdown of foreign material by phagocytosis
     • autolysis to kill cell

3. Homeostasis

   • The Maintenance of Internal Environments Within the Body
   • Acts as a Buffer Against External Changes
   • The Brain
     • somatic nervous system - conscious
     • autonomic - unconscious
       • symapthetic
         • noradrenaline
       • parasympathetic
         • acetylcholine
       • different receptors change what happens with a signal
   • Negative Feedback
     • temperature control
     • a sensor leads to a reversal of the change in parameter it sensed
     • the set point is the point at which negative feedback trys to return the parameter to
     • 2 effectors - one for too great and one for too low
   • Positive Feedback
     • a sensor leads to an exaggeration of the paramenter it sensed
     • blood clotting
     • labour contractions
   • Local Autoregulation
     • capillary blood flow
     • sympathetic input causes dilation of smooth muscle
     • capillaries only 2/3 open - 20% maximal blood flow
     • factors that cause dilation
       • hypoxia
       • lactic acid
       • nitric oxide
       • potassium
     • vasomotor tone
     • implications of excerise
       • vasodilation causes a drop in blood pressure
       • locally produced acid enters the blood
       • detected by baro- and chemo- receptors which signal the brainstem nuclei
       • reflex changes in breathing and heart rate restore homeostasis
   • Hormones
     • control long term homeostasis
     • come in antagonistic pairs

4. Acid-Base Balance

   • Challenges
     • Diet - proteins and fats broken down into acidic products
     • Metabolism - in/complete carbohydrates, bicarb and lactic acid; incomplete fats, ketoacids
     • pathology - vomiting,renal failure,retention of CO2 acidosis; diarrhoea, diabetes, loss of CO2 alkalosis
   • Responses to Challenges
     • buffering - bicarbonate, protein and phosphate
     • respiratory compensation - excess CO2 blown off
       • peripheral
         • detect CO2 and protons
       • central
         • detect CO2
       • both drive an increase in rate and depth of breathing
     • renal compensation - acid secretion, bicarb synthesis and phosphate homeostasis
       • secretion of protons or bicarb into the urine
       • retention of bicarb
       • creation of bicarb
       • excretion of ammonia
       • regulation of buffers
     • buffering hides the problem
   • Disturbances
     • acidosis
       • respiratory - CO2 retention, impaired ventilation
       • metabolic - creation or ingestion of acids, renal failure, diarrhoea
     • alkalosis
       • respiratory - CO2 deficit, hyperventilation
       • metabolic - loss of acid, ingestion of antacids