Introductory Physiology Lectures 1 – 8 PDF

1 Introductory Physiology Lectures 1 – 8 Foundations for understanding Systems & Integrated Physiology 1 Overview and Scientific Process Think! How the body 2-3 Systems, tissues, cells (gene...

1 Introductory Physiology Lectures 1 – 8 Foundations for understanding Systems & Integrated Physiology 1 Overview and Scientific Process Think! How the body 2-3 Systems, tissues, cells (genes), body water is organised Basis for 4-7 Transport processes (across cell membranes) Understanding Bio-electric potentials (and ion distribution) System Function Just 1 of 11 8 Nerve Physiology systems Slide 8 - www.youtube.com/watch?v=-1aZj6v6dxc 2 Module Objective Lay foundation for understanding Systems & Integrated Physiology... & … the relationship between normal physiological processes and disease … … in the context of homeostasis 3 Lecture 3: Epithelial Tissue & Body Water Learning Objectives Epithelial Tissue Overview of body water Mechanisms of water and solute transport Concept of water balance and kidney function Homeostasis - fundamental principle of physiology 4 Tissue IV – Epithelial Function Protects, secretes, absorbs, excretes Location Covers body surfaces (inside & out) and glands Distinguishing Characteristics No blood vessels, reproduced readily, tightly packed cells Defines boundary of body compartments 5 Check Out your own Epithelial Cells Skin - normally dry Sweat glands (secrete sweat onto skin) Mouth - normally moist Lips - interface between skin/mouth (no sweat glands – lips get dry) Lungs - exchange gases (moisture levels tightly regulated) Gut - absorb nutrients Kidneys - absorb and filter Blood vessels 6 Epithelial Cells form Membranes… … which define boundaries between body compartments Stratified or Monolayers Apical Basolateral Basement membrane Apical surface - exposed to outside or internal open space Basolateral surface - basement membrane links to connective tissue Cells held to each other by tight junctions Keratinised (dead/dry) or non-keratinised (alive/moist) e.g. outer skin layer e.g. inside mouth, lungs 7 … and glands Which secrete into or out of the body Pancreas Endocrine - Insulin secreted into blood Exocrine - digestive enzymes secreted into GIT Testes/ovaries Endocrine - testosterone/estrogen into blood Exocrine - sperm and ova 8 … and glands Which secrete into or out of the body Exocrine glands Endocrine glands secrete via ducts secrete inside the body e.g. tear glands Kidneys - Renin sweat glands salivary Pineal Gland - Melatonin glands* gastric *why are these glands glands* classified as “Outside”? 9 Inside versus Outside Inside blood or lymph system Outside Skin, lung, kidney tubules or digestive tract 10 Lecture 3: Epithelial Tissue and Body Water Learning Objectives Epithelial Tissue Overview of body water and mechanisms of water/solute transport Concept of water balance and Kidney function Introduce homeostasis - fundamental principle of physiology  Water 11 Why do we lose water when we exercise? How do we know how much to drink to replace it? How does body maintain water balance? Why does eating salty popcorn make us thirsty? Why does alcohol dehydrate us? Why does drinking coffee the morning after the night before make us more dehydrated? 12 Body Water – Volume and Composition Total Body H2O of 70 kg human = 42 L That’s a lot of water (55-60% by mass) - equivalent of 74 pints ! N.B. Expt to calculate body water - see extra slides on CANVAS 13 Body Water – where is it? Total Body H2O of 70 kg human = 42 L 14 Some is inside cells… There are ~50 million million cells in the body 15 … so the rest must be outside those cells There are ~50 million million cells in the body 16 Body Water – where is it? Vote with your feet Everyone stand up Sit down if you think most of the water is inside our cells intracellular fluid Stay standing it you think most of the water is outside our cells extracellular fluid 17 Total Intracellular Fluid (ICF) = 28 L 67% of all water is within the 50 million million cells in the body 18 Intersititial fluid is the Total Extracellular Fluid = 14 L extracellular fluid that surrounds cells Interstitial fluid is not intracellular fluid 3 L of plasma 11 L of interstitial (liquid component fluid (solution of blood) bathing cells) Latin Extra - outside Inter – between Intra – within 33% of all water surrounds the 50 million million cells in the body 19 Body Water – Composition of ICF and ECF Different solutes/concentrations, but osmolarity is same in both = no net water movement ECF 14 L ICF 28 L Example Plasma Muscle Cell Solutes (mM) Na+ 150 (high) 10 (low) K+ 5 (low) 150 (high) Ca2+ 2 (high) 0.0004 (low) Other ~123 (variable) ~120 (variable) Osmolarity (mOsm) ~280 ~280 See Lecture 4 and Lab 1 20 Daily balance of H2O (on a typical day) Daily loss - kidneys (urine) 1.5 L - lungs 0.3 L - skin/sweat 0.6 L - faeces 0.1 L 2.5 L Intake must match loss to avoid dehydration Mathematically, we could last almost 17 days (2.5 L x 17 = 42.5 L) Physiologically, 3 days without any water intake could be fatal Exercise, external temperature, coffee/alcohol/salt intake and/or disease can dramatically affect rate of water loss… …so how do we take in water, get rid of excess water, and monitor this to make sure we maintain our 42 litres of body water?  How does H2O cross epithelia and enter body? 21 Drink water i) Absorbed in gut ii) Reabsorbed in kidney  How does H2O cross epithelia and leave body? 22 i) Secretion & evaporation: lungs & skin ii) Secretion and/or lack of absorption (diarrhoea) in gut (Micro/Path) iii) Filtration/ secretion and/or lack of reabsorption in kidney 23 Water can cross epithelia… … but it cannot cross a lipid bilayer (so, how does it get in & out?) Filtration of Blood in Kidneys Gaps between cells in glomerulus (Re)Absorption/Secretion in other Epithelial Cells Transport proteins form pores in the membrane (lecture 4) 24 Filtration in Kidneys It’s half of what the kidneys do Plasma is continually filtered through kidneys All water and small solutes (