Animal Physiology Dr. Kashif Asghar Email: drkashifasghar@gmail.com

Pathophysiology: how physiological processes are altered in disease or injury

Physiology

How Organism function

Levels of organization of human body

Chemical and Molecular Level Molecular composition of the human body Water 67% Proteins 20% Carbohydrates 3% Lipids 10% Elemental composition Hydrogen 62% Oxygen 26% Carbon Nitrogen 1.5% Other Elements: Calcium Phosphorus Potassium Sodium Sulfur Chlorine Magnesium Iron Iodine Trace elements 0.2% 0.06% 0.05% 0.04% 0.03% 0.0005% 0.0000003% (see caption)

Levels of Organization: Cellular Basic units of structure and function

Levels of Organization: Tissue Epithelial tissue Connective tissue Muscle tissue Nervous tissue Cells with similar functions grouped into the 4 primary tissues

Skin—The Largest Organ Outer layer of protective cornified epidermis Next layer the dermis contains connective tissue, glands, blood vessels (BVs), nerves Inner layer the hypodermis contains adipose tissue, BVs, nerves

Stem Cells Most cells in organs are highly specialized or differentiated Many organs retain small populations of adult stem cells less differentiated so can become many cell types Example: bone marrow stem cells can give rise to all of the different blood cell types

Body-Fluid Compartments Our body has both intracellular and extracellular compartments: Intracellular - inside cells (cytoplasm) Extracellular - outside cells (blood plasma, interstitial fluid) Compartments separated by the cell’s plasma membrane

Levels of Organization: Organ System Chemical or Molecular Levels Atoms in combination Complex protein molecules Protein filaments Organ System Level The heart Cellular Level Heart muscle cell Tissue Level Cardiac muscle tissue Organ Level Cardiovascular Reproductive Urinary Digestive Respiratory Lymphoid Endocrine Nervous Muscular Skeletal Integumentary Organism

Levels of Organization: Organ System Organ System Level Cardiovascular Reproductive Urinary Digestive Respiratory Lymphoid Endocrine Nervous Muscular Skeletal Integumentary Organism Level Organs located in different regions of the body that perform related functions are grouped into systems

Organismal Level Chemical level Atoms combine to form molecules. Cellular level Cells are made up of molecules. Tissue level Tissues consist of similar types of cells Organ level Organs are made up of different types of tissues. Organ system level Organ systems consist of different organs that work together closely. Organismal level The human organism is made up of many organ systems. Cardiovascular system Organelle Molecule Atoms Smooth muscle cell Smooth muscle tissue Connective tissue Blood vessel (organ) Heart Blood vessels Epithelial tissue 1 2 3 4 5 6

History of Physiology Arist (384 – 322 BCE) – speculated on body function Erasistratus (304 -~250 BCE) considered the father of physiology - applied physical laws to the study of human function Galen (130 -201 A.D.) - believed the working body was not understandable without knowledge of its structure William Harvey (1578–1657)-blood pumped in a closed system of vessels Claude Bernard (1813 – 1878) – internal environment remains constant despite everchanging external environment Walter Cannon (1871 – 1945) – coined the term ‘homeostasis’

Introduction to basic concepts of physiology Scientific Method Levels of Organization Homeostasis - Feedback loops

Homeostasis Our organ systems work together to maintain homeostasis despite constant challenges

Homeostasis Maintenance of a state of dynamic constancy internal conditions are stabilized above and below a physiological set point by negative feedback loops

Homeostasis and Negative Feedback Loops All physiological parameters have a set point ‘X’ Sensor: Detects deviation from set point Integrating center: Determines response Effector: Produces response to re-establish X

Homeostasis Negative feedback loops – body temperature, blood sugar, blood pressure Example: control of body temperature Set point: 37 °C Sensor: Temperature receptors Integrating center: Brain Effector: sweat glands/muscles

Control of blood glucose level (Insulin & Glucagon)

Homeostasis: Negative Feedback Example: control of blood sugar Set point: 5 mmol/L Sensor: pancreatic cells Integration: Endocrine system Effector: insulin and glucagon

Homeostasis: Negative Feedback Example: control of blood pressure Set point: normal blood pressure Sensor: barorecptors Integration Center: brain Effector: heart / arteries

Homeostasis and Positive Feedback Does not maintain homeostasis and is rare Occurs when the body needs to amplify a process Producing blood clots Creates the LH surge that causes ovulation Between the uterus and oxytocin secretion during childbirth

Scientific Method Discovery-based science - making observations and measurements regarding the natural world Hypothesis-based science -conduct and analyze experiments to test a hypothesis 1. develop a testable hypothesis to answer a scientific question based on natural observations 2. design and conduct experiments in an objective, unbiased, repeatable manner 3. analyze data and form conclusions that either support or deny the hypothesis

Discovery-based Science Is there a difference in resting heart rate between people who exercise and those who don’t? - Measure heart rate in people who exercise - Measure heart rate in people who don’t exercise - Analyze data and from conclusions Study establishes a correlation (relationship) between exercise and heart rate but not causation

Hypothesis-based Science Hypothesis - a tentative answer to a question - an explanation on trial

Scientific Method Hypothesis-based science: Form hypothesis: question to be answered People who exercise regularly have lower resting heart rate Treatment group: individuals subject to the test condition Randomly choose a group who must exercise (experimental group) Control group: similar individuals not subjected to treatment Randomly choose a group that is not allowed to exercise (control) Dependent variable: outcome you are measuring Heart rate Unbiased: double-blind (placebo) study Random groups Analyze data and form conclusions “Controlled experiment” establishes causation

Scientific Method to Develop New Drugs Biomedical research - test effectiveness & toxicity of a new drug - first in vitro (tissue culture) then in vivo (animal models) Clinical trials performed: Phase I Trials: Toxicity and metabolism tested in healthy human volunteers (no toxic effects observed) Phase II Trials: Effectiveness and toxicity tested in target population (effective with minimal toxicity) Phase III Trials: Widespread test of drug in diverse population (gender, ethnicity, other health problems) Phase IV Trials: Drug is tested for other potential uses (sent to FDA for approval)

Circulatory system