Physiology Essentials 100 Lecture Notes PDF

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Summary

 Anatomy – the study of body structures  Physiology – the study of how living organisms perform their functions  Homeostasis – existence of a stable internal environment (vital for an organism’s survival)  Pathology – the study of abnormal body structure  Pathophysiology – the study of abnormal...

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Physiology Essentials 100 – BIOL 1051          

Anatomy – the study of body structures Physiology – the study of how living organisms perform their functions Homeostasis – existence of a stable internal environment (vital for an organism’s survival) Pathology – the study of abnormal body structure Pathophysiology – the study of abnormal body function Disorder (condition, illness, or sickness) – an irregularity, disturbance or interruption of normal or regular bodily function Disease – a particular distinctive process in the body with a specific cause and characteristic symptoms Sign – an objective indication of disease (something measured eg. change in heart rate or blood pressure) Symptom – a subjective indication of disease (something described eg. Tiredness or nausea) Clinical manifestation – clinical overarching terms for signs and symptoms

Medical Terminology:  Universal language enabling scientists/clinicians for communication between them  Medical terms made up of basic building blocks or ‘word parts’ o Word roots – basic meaningful parts of a term, cannot be broken down into another term with another definition eg. ‘kinein’ movement o Prefixes – word elements that are attached at the beginning of words to modify their meaning but cannot stand alone eg. ‘a’ without o Suffixes – word elements or letters added to the end of a word or word part to form another term eg. ‘ia’ state or condition o Akinesia (A-kines-ia) a condition without movement

Anatomical Terminology:  Superior – above  Inferior – below  Medial – toward midline 1

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Lateral – away from midline Proximal – towards point of attachment of a limb to the trunk Distal – away from point of attachment of a limb to the trunk Superficial – near surface Deep – far from surface Posterior – back surface Anterior – front surface Dorsal – back Ventral – belly Caudal – toward the tail

Anatomical Planes:

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cavities: Closed, fluid-filled cavities that contain organs of the trunk Protect organs Permit changes in organ shape Organs enclosed by these cavities are known as viscera

Levels of organisation:  Chemical level o Atom: smallest stable units of matter composed of subatomic particles  Protons = positive electrical charge

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 Neutrons = neutral electrical charge  Electrons = negative electrical charge o Element: pure substance composed of atoms of only one kind o Molecule: chemical structure held together by shared electrons eg. O2 o Compound: pure chemical substance made up of atoms of two or more different elements in fixed proportion eg. NaCl Cellular Level – cells are smallest living units in the body Tissue level – group of cells working together to perform one or more specific functions Organ level – organs are made of two or more tissues working together to perform a specific function Organ system level – group of organs that interact to perform a particular function Organism level – an individual life form made up of 11 organ systems that interact to perform a particular function

Organ Systems: Integumentary system  Major organs – skin, hair, sweat glands, nails  Functions – protect against environment hazards and help regulate body temperature Skeletal system  Major organs – bones, cartilage, ligaments  Functions – provide support and protection for other tissues, store calcium and other minerals and form blood cells Muscular system  Major organs – skeletal muscles and tendons  Functions – movement, protection and support for other tissues and muscle contraction generates heat Nervous system  Major organs – brain, spinal cord, peripheral nerves, sense organs  Functions – direct immediate responses to stimuli, coordinate or moderate activities of other organ systems, provide and interpret sensory information about external and internal conditions and cognition and memory Respiratory system  Major organs – nasal cavities, sinuses, larynx, trachea, bronchi, lungs, alveoli  Functions – deliver air to lung alveoli (where gas exchange occurs), provide oxygen to and remove carbon dioxide from, bloodstream, produce sounds for communication and facilitate odour detection Cardiovascular system  Major organs – heart, blood, blood vessels  Functions – distribute blood cells, water, and dissolved substances (eg. Nutrients, waste products, oxygen and carbon dioxide) and distribute heat and assist in maintenance of body temperature Lymphatic system  Major organs – spleen, thymus, lymphatic vessels, lymph nodes 3

Physiology Essentials 100 – BIOL 1051 Functions – defend against infection and disease and return tissue fluids to the bloodstream Endocrine system  Major organs – pituitary gland, pancreas, gonads, thyroid gland, adrenal glands, endocrine tissues in other systems  Functions – direct long-term changes in the activities of other organ systems, adjust metabolic activity and energy use and control many structural and functional changes during development Digestive system  Major organs – teeth, tongue, pharynx, esophagus, stomach, small and large intestine, liver, gallbladder, pancreas  Functions – process and digest food, absorb nutrients and conserves water and store energy sources Urinary system  Major organs – kidneys, ureters, urinary bladder and urethra  Functions – excrete waste products from the blood, control water balance by regulating volume of urine produced, regulate blood ion concentrations and pH and help regulate blood pressure 

Homeostasis (homeo = unchanging + stasis = standing)  Homeostasis – maintenances of a stable internal environment within a normal range eg. Body temperature, BP, HR, BGL and is vital for organism survival  Homeostatic regulation – adjustment of physiological processes to preserve homeostasis o Two general mechanisms: autoregulation and extrinsic regulation  Homeostatic regulatory mechanism – receptor, control centre, effector, negative feedback, positive feedback  Purpose of physiological processes – prevent harmful changes in the composition of body fluids and the environment inside our cells  Autoregulation: o Adjustment in response to a local environmental change (eg. When tissue oxygen levels decrease, nearby cells release a chemical that widens, or dilates, local blood vessels)  Extrinsic regulation: o Adjustment in response to an environmental change, results from activities of the nervous system or endocrine system

o Nervous system – rapid, short-term, evokes a very specific response (eg. Removing hand from hot surface – excessive heat produces a painful, localised disturbance of homeostasis)

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o Endocrine system – endocrine organs/tissue release hormones (chemical messages) into bloodstream, hormones affect tissues and organs throughout the body, delay between stimulus (environmental change) and response, response can last for days (eg. Long-term regulation of blood volume and composition) Homeostatic regulatory mechanism consists of 3 components: o Receptor – sensor that is sensitive to (detects) a particular stimulus or environmental change (eg. Thermometer) o Control centre – receives and processes the information supplied by the receptor and sends out commands (eg thermostat) o Effector – cell or organ that responds to the commands of the control centre activity either opposes or enhances the stimulus (eg air conditioner) Negative feedback o Effector activates by control centre opposes (negates) the original stimulus o Counteracts or minimises a change (variation outside the set point triggers an automatic response that corrects the situation) o Common (eg. Control of body temperature and blood pressure) Positive feedback o Initial stimulus produces a response that amplifies or enhances the original change in conditions o Uncommon (because it produces extreme responses) o Typically found when a dangerous or stressful process must be completed quickly to restore homeostasis (eg. Blood clotting and labour contractions during childbirth)

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Homeostatic regulatory mechanism requires coordinated activity in multiple organ systems (eg. Homeostatic regulation of blood pressure involves cardiovascular system, nervous system, urinary

system, and endocrine system) o Each organ system functions to maintain a state of equilibrium (balance) to keep vital conditions within a normal range o Any adjustment made by one organ system has a direct and/or indirect effect on a variety of other systems Homeostatic imbalance – caused by: infection, injury, genetic abnormality Failure of homeostatic mechanisms to fully compensate leads to malfunction of the organ system (disorder – disturbance or abnormality of function and indicates incomplete health) (disease – specific term reserved for the characteristic or distinguishing features that correspond to a particular pathophysiological condition

Cells:  Smallest living unit of an organism  Each cell maintains homeostasis at the cellular level  Human body contains two general classes of cells o Sex cells (germ or reproductive cells) - sperm in males and oocytes (or eggs) in females o Somatic cells (our focus) – all other cells in the body (terminology: soma, body) Somatic Cells:  Structure: o Intracellular: inside of the cell. 6

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o Extracellular: surrounding environment outside of the cell o Plasma membrane: outer boundary o Cytoplasm: material between plasma membrane and nucleus o Nucleus: control centre for cellular operations Plasma Membrane: Consists of – lipids (42% of plasma membrane), proteins, cholesterol and carbohydrates o Function – physical barrier intracellular and extracellular environment, regulates exchange of molecules (eg. Nutrients + waste products) between intracellular and extracellular environment (selectively permeable), sense changes in extracellular environment (eg. Composition, concentration, or pH of extracellular fluid – via receptors that allow cell to recognise and respond to specific molecules) o Structural support – specialised connections between plasma membranes of neighbouring cells or between plasma membranes and extracellular materials, give tissues stability Phospholipid bilayer – hydrophilic head (water 100 000 proteins Determines cell structure and function be controlling: o Type and amount of protein that is synthesised and under which circumstances that protein synthesis occurs Most cells contain one nucleus (exceptions eg. Skeletal muscle cells – many nuclei, mature red blood cells – no nucleus) Structure – contains nucleic acids (eg. DNA and RNA) Nucleic acids store and process information at the molecular level inside cells in two classes o Deoxyribonucleic acid – encode the information (provide recipe) for building proteins and enzymes, controls cell structure and function (via protein synthesis) and cellular metabolism (via enzyme synthesis) *DNA nucleotides PAIR OF STRANDS o Ribonucleic acid – builds specific proteins using the information provided by DNA *RNA nucleotides SINGLE STRAND Nucleic acids contain nucleotides that consist of a sugar molecule, phosphate group, and nitrogenous base – DNA a+t, g+c o Adenine o Guanine o Cytosine o Thymine o Uracil  Nitrogenous base pairs are linked with weak hydrogen bonds DNA in the nucleus wraps around histones to form nucleosomes Nucleosomes form coils that can be tight or loose o Chromosomes = tight o Chromatin = loose Information storage: DNA contains the recipe for making (synthesising) proteins Gene: o Section of a DNA strand that specifies the amino acids needed to produce a specific protein o Each gene comes in various forms called alleles o Resultant proteins give an organism its’ inherited features (eg. Eye colour) o Genetic code = the chemical language of cells

Protein synthesis: 8

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DNA to mRNA = the process of TRANSCRIPTION o Gene on DNA produces messenger RNA (mRNA) the template for protein synthesis o mRNA leaves nucleus and attaches to a ribosome DNA->transcription->mRNA->translation->protein o Free ribosomes synthesise proteins that will be released into cytosol o Fixed ribosomes synthesise proteins that will be passed to rough endoplasmic reticulum (ER) o Rough endoplasmic reticulum modifies proteins and passes it toward Golgi apparatus o Further modification and packaging of protein and glycoprotein occurs in golgi apparatus o Vesicle carries modified protein away from golgi apparatus. One type of vesicle becomes a lysosome o Two other vesicle types move to plasma membrane  Secretory vesicles – fuse to membrane and empty contents into extracellular space  Membrane renewal vesicles – add new proteins (and lipids) to plasma membrane

Transport of Molecules (across plasma membrane)  Plasma membrane is a barrier between the cytoplasm and extracellular fluid o But nutrients and waste products are transported across the plasma membrane o Thus, plasma membrane is selectively permeable (permits free passage of some substances and prevents passage of others)  Transport is either passive or active: o Passive – requires no energy expenditure (eg diffusion, osmosis and facilitated diffusion) o Active – requires the cell to expend energy (ATP) (eg. Endocytosis, exocytosis and active transport)  Passive transport 1 – diffusion o Net movement of a substance from an area of high concentration to an area of lower concentration (concentration gradient = difference between high and low concentrations) o Down the concentration gradient = movement of a substance from an area of higher concentration to an area of lower concentration

o Simple diffusion = gases (oxygen and carbon dioxide) and lipid-soluble molecules (fatty acids) 9

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o Channel-mediated diffusion (use of channel protein) = small water soluble molecules and ions (potassium) Passive transport 2 – osmosis o Diffusion of water across a semi-permeable membrane (channel mediated diffusion) to remove concentration gradient between intracellular and extracellular environment Passive transport 3 – facilitated diffusion o Integral proteins bind specific ions or organic substrates and carry them across the plasma membrane (down their concentration gradient) via carrier-mediated/facilitated diffusion (passive transport of large water-soluble molecules eg. Glucose) Active transport 1 – active transport o Integral proteins bind specific ions and carry them across the plasma membrane (against their concentration gradient) via carrier-mediated transport (eg. Exchange pump) (ATP is used to pump sodium and potassium across the plasma membrane) Active transport 2 – exocytosis o Vesicle fuses with the plasma membrane to move substances out of the cell (bulk transport – can be more than one molecule at a time) Active transport 3 – endocytosis o Extracellular materials are packaged in vesicles at the plasma membrane and transported into the cell – there are three types (also bulk transport of more than one molecule at a time)  Receptor mediated endocytosis = hormones  Pinocytosis = nutrients “liquids”  Phagocytosis = bacteria “solids”

Intercellular Communication  Inter = between  Intra = within  5 types or ‘mechanisms’ of intercellular communication o Endocrine communication o Paracrine communication o Autocrine communication o Synaptic communication o Direct communication  Endocrine communication o When a cell releases a chemical message (hormone) into the bloodstream to affect the activity of specific (target) cells in another part of the body o Hormone = chemical that is secreted by one cell and travels through the bloodstream to affect the activity of specific cells in another part of the body  Alters operations of target cells by changing the typs, quantities or activities of enzymes and structural proteins 10

Physiology Essentials 100 – BIOL 1051 Target cells can be located in different parts of the body and thus a single hormone can alter the activity of multiple tissues and organs at the same time  Effect on target cells is slow to appear and typically lasts for days o Hormones are effective in coordinating cell, tissue and organ activities on a sustained, long-term basis Paracrine communication o When a cell releases a chemical message into the extracellular fluid to transfer information from cell to cell, primarily within a single tissue (eg. At a local level) – chemicals involved are called ‘paracrines’ o Most cells release paracrines but only specialised cells produce hormones Autocrine communication o When the chemical messages affect the same cells that secrete them o Chemicals involved are called ‘autocrines’ (eg. Prostaglandins – secreted by smooth muscle cells to cause contraction of those cells) Synaptic communication o When a neuron releases a chemical message (neurotransmitter) at a chemical synapse with target cell o Rapid, fast and short-lasting form of intercellular communication that is ideal for ‘crisis management’ (eg. Immediate response to stressful situation) Direct communication o Occurs between two cells of the same type, and the cells must be in physical contact o Two cells exchange ions and molecules across gap junctions via diffusion (and thus function as a single entity) o Rare (eg. Coordinate ciliary movement among epithelial cells, coordinate contraction of cardiac muscle cells, facilitate propagation of action potentials across electrical synapses in the nervous system) 

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Physiology Essentials 100 – BIOL 1051

Mitosis:  Involves nuclear division and DNA replication  Function in adults: o Replace damaged cells or cells that have undergone programmed cell death (apoptosis) o Not all somatic cells can undergo mitosis o Tumour = abnormal cell growth and division

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Physiology Essentials 100 – BIOL 1051 Tissue:  Four types of tissue – connective, epithelial, nervous, muscle  Tissue is a group of cells working together to perform specific functions  Connective: o Functions:  Fills internal spaces  Provides structural support and protection for other tissues/organs  Transports fluids and dissolved materials within the body  Store energy o Consists of:  Specialised cells  Extracellular protein fibres (collagen fibres, reticular fibres, or elastic fibres)  Fluid called ‘group substance’ o Classification:  Connective tissue proper (loose or dense)  Fluid connective tissue  Supporting connective tissue  Epithelial: o Layers of cells that cover internal and external surfaces (internal – thoracic cavity and inner surface of blood vessels. External – skin and lining of respiratory, digestive, reproductive and urinary tracts) o Glands – structures that produce fluid secretions (glands are attached to or derived from epithelia) o Functions:  Provide physical protection  Control permeability  Aid sensation (nervous system function)  Produce specialised secretions o Consists of:  Epithelial cells – have an exposed surface (faces exterior of body or an internal space) and a base  bound closely together by cell junctions  attach to underlying connective tissue via basement membrane  avascular (lack blood vessels)  receive nutrients via diffusion or absorption  regeneration (via cell division) o Epithelial cells are not all the same  Some are specialised to perform specific functions (eg. Some have microvilli – controlling permeability via absorption or secretion. Or some have motile cilia – for providing protection via movement of substances over the epithelial surface)  Differ in shape  Differ in number of layers of cell...