Copyright © 2010 Pearson Education, Inc. Homeostasis & Requirements of Life

Copyright © 2010 Pearson Education, Inc. Introductory Lecture for Bio 260 Adapted from Chapter 1, Marieb’s Human Anatomy and Physiology What should you emphasize? Principle of complimentarity Levels of structural organization Necessary life functions & survival needs Homeostasis

Copyright © 2010 Pearson Education, Inc. Overview of Anatomy and Physiology  Anatomy – the study of the structure of body parts and their relationships to one another  Physiology – the study of the function of the body structural systems

Copyright © 2010 Pearson Education, Inc. Physiology  The study of functions of specific organ systems Examples: Renal – kidney functions in filtering the blood and osmoregulation Neurophysiology – workings of the brain, neurons, and receptors Cardiovascular – operation of the heart and blood vessels  Functions of the body often best understood at the cellular or molecular level

Copyright © 2010 Pearson Education, Inc. Physiology  Essential tools for the study of physiology:  Ability to focus at many levels (from systemic to cellular and molecular)  Basic physical principles (e.g., electrical currents, pressure, and movement)  Basic chemical principles

Copyright © 2010 Pearson Education, Inc. Principle of Complementarity  Anatomy and physiology are inseparable. Function always reflects structure What a structure can do depends on its specific form

Copyright © 2010 Pearson Education, Inc. Levels of Structural Organization Chemical – atoms and molecules (Chapter 2) Cellular – cells and their organelles (Chapter 3) Tissue – groups of similar cells (Chapter 4) Organ – contains two or more types of tissues Organ system – organs that work closely together Organismal – all organ systems

Copyright © 2010 Pearson Education, Inc. Cardiovascular system Organelle Molecule Atoms 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. Smooth muscle cell Smooth muscle tissue Connective tissue Blood vessel (organ) Heart Blood vessels Epithelial tissue Smooth muscle tissue Figure 1.1

Copyright © 2010 Pearson Education, Inc. Overview of Organ Systems Note major organs and functions of the 11 organ systems (Fig. 1.3)

Copyright © 2010 Pearson Education, Inc. Figure 1.3a Nails Skin Hair (a) Integumentary System Forms the external body covering, and protects deeper tissues from injury. Synthesizes vitamin D, and houses cutaneous (pain, pressure, etc.) receptors and sweat and oil glands.

Copyright © 2010 Pearson Education, Inc. Figure 1.3b Bones Joint (b) Skeletal System Protects and supports body organs, and provides a framework the muscles use to cause movement. Blood cells are formed within bones. Bones store minerals.

Copyright © 2010 Pearson Education, Inc. Figure 1.3c Skeletal muscles (c) Muscular System Allows manipulation of the environment, locomotion, and facial expression. Main- tains posture, and produces heat.

Copyright © 2010 Pearson Education, Inc. Figure 1.3d Brain Nerves Spinal cord (d) Nervous System As the fast-acting control system of the body, it responds to internal and external changes by activating appropriate muscles and glands.

Copyright © 2010 Pearson Education, Inc. Figure 1.3e Pineal gland Pituitary gland Thyroid gland Thymus Adrenal gland Pancreas Testis Ovary (e) Endocrine System Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells.

Copyright © 2010 Pearson Education, Inc. Figure 1.3f (f) Cardiovascular System Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc. The heart pumps blood. Heart Blood vessels

Copyright © 2010 Pearson Education, Inc. Figure 1.3g Lymphatic vessels Red bone marrow Thoracic duct Thymus Spleen Lymph nodes (g) Lymphatic System/Immunity Picks up fluid leaked from blood vessels and returns it to blood. Disposes of debris in the lymphatic stream. Houses white blood cells (lymphocytes) involved in immunity. The immune response mounts the attack against foreign substances within the body.

Copyright © 2010 Pearson Education, Inc. Figure 1.3h Nasal cavity Bronchus Pharynx Larynx Trachea Lung (h) Respiratory System Keeps blood constantly supplied with oxygen and removes carbon dioxide. The gaseous exchanges occur through the walls of the air sacs of the lungs.

Copyright © 2010 Pearson Education, Inc. Figure 1.3i Liver Oral cavity Esophagus Large intestine Stomach Small intestine Rectum Anus (i) Digestive System Breaks down food into absorbable units that enter the blood for distribution to body cells. Indigestible foodstuffs are eliminated as feces.

Copyright © 2010 Pearson Education, Inc. Figure 1.3j Kidney Ureter Urinary bladder Urethra (j) Urinary System Eliminates nitrogenous wastes from the body. Regulates water, electrolyte and acid-base balance of the blood.

Copyright © 2010 Pearson Education, Inc. Figure 1.3k-l Prostate gland Ductus deferens Penis Testis Scrotum Ovary Uterine tube Mammary glands (in breasts) Uterus Vagina Overall function is production of offspring. Testes produce sperm and male sex hormone, and male ducts and glands aid in delivery of sperm to the female reproductive tract. Ovaries produce eggs and female sex hormones. The remaining female structures serve as sites for fertilization and development of the fetus. Mammary glands of female breasts produce milk to nourish the newborn. (k) Male Reproductive System (l) Female Reproductive System

Copyright © 2010 Pearson Education, Inc. Organ Systems Interrelationships  All cells depend on organ systems to meet their survival needs  Each organ system does not function independently, but work cooperatively to perform necessary life functions Example: Digestive and respiratory systems, in contact with the external environment, take in nutrients and oxygen

Copyright © 2010 Pearson Education, Inc. Figure 1.2 Digestive system Takes in nutrients, breaks them down, and eliminates unabsorbed matter (feces) Respiratory system Takes in oxygen and eliminates carbon dioxide Food O2O2 CO 2 Cardiovascular system Via the blood, distributes oxygen and nutrients to all body cells and delivers wastes and carbon dioxide to disposal organs Interstitial fluid Nutrients Urinary system Eliminates nitrogenous wastes and excess ions Nutrients and wastes pass between blood and cells via the interstitial fluid Integumentary system Protects the body as a whole from the external environment Blood Heart Feces Urine CO 2 O2O2 Organ Systems Interrelationships  Nutrients and oxygen are distributed by the blood  Metabolic wastes are eliminated by the urinary and respiratory systems

Copyright © 2010 Pearson Education, Inc. Necessary Life Functions 1.Maintaining boundaries – the internal environment remains distinct from the external environment Plasma membranes of cells Skin of an organism 2.Movement (contractility) Of body parts (skeletal muscle) Of substances (cardiac and smooth muscle)

Copyright © 2010 Pearson Education, Inc. Necessary Life Functions 3.Responsiveness – ability to sense changes in the environment (internally & externally) and respond to them Withdrawal reflex Control of breathing rate 4.Digestion Breakdown of ingested foodstuffs Absorption of simple molecules into blood

Copyright © 2010 Pearson Education, Inc. Necessary Life Functions 5.Metabolism – all the chemical reactions that occur in the body that allow the organism to function Catabolism and anabolism 6.Excretion – The removal of wastes from metabolism and digestion Urea, carbon dioxide, feces

Copyright © 2010 Pearson Education, Inc. Necessary Life Functions 7.Reproduction – producing the next generation Cellular – an original cell divides and produces two identical daughter cells for growth or repair Organismal – sperm and egg unite to make a whole new person (production of offspring) 8.Growth – increase in size of a body part or of the entire organism

Copyright © 2010 Pearson Education, Inc. Survival Needs 1.Nutrients Sources of energy to power chemical reactions and building materials Carbohydrates, fats, proteins, minerals, vitamins 2.Oxygen Essential for energy release (ATP production)

Copyright © 2010 Pearson Education, Inc. Survival Needs 3.Water Most abundant chemical in the body Provides the environment for chemical reactions 4.Normal body temperature Affects rate of chemical reactions 5.Appropriate atmospheric pressure For adequate breathing and gas exchange in the lungs

Copyright © 2010 Pearson Education, Inc. Homeostasis  Homeostasis – ability to maintain a relatively stable internal environmental conditions in an ever-changing outside world  The internal environment of the body is in a dynamic state of equilibrium

Copyright © 2010 Pearson Education, Inc. Homeostatic Control Mechanisms  Involve continuous monitoring and regulation of many factors (variables)  Variables (O 2 level, body temperature, blood pressure, etc) alter body functions  Nervous and endocrine systems accomplish the communication via nerve impulses and hormones

Copyright © 2010 Pearson Education, Inc. Components of a Control Mechanism 1.Receptor (sensor) Monitors the environment Responds to stimuli (changes in controlled variables) 2.Control center Determines the set point at which the variable is maintained Receives input from receptor Determines appropriate response

Copyright © 2010 Pearson Education, Inc. Components of a Control Mechanism 3.Effector Receives output from control center Provides the means to respond to stimuli Response acts to reduce or enhance the stimulus (feedback)

Copyright © 2010 Pearson Education, Inc. Stimulus produces change in variable. Receptor detects change. Input: Information sent along afferent pathway to control center. Output: Information sent along efferent pathway to effector. Response of effector feeds back to reduce the effect of stimulus and returns variable to homeostatic level. ReceptorEffector Control Center BALANCE Afferent pathway Efferent pathway IMBALANCE Figure 1.4 Homeostatic Control Mechanisms

Copyright © 2010 Pearson Education, Inc. Negative Feedback  In negative feedback systems, the response reduces or shuts off the original stimulus  Produces an opposite effect to the current state

Copyright © 2010 Pearson Education, Inc. Negative Feedback  Example (non-biological) – Regulation of room temperature by a thermostat  Examples (biological) – Regulation of body temperature (a nervous mechanism) Regulation of blood glucose by insulin and glucagon (an endocrine mechanism)

Copyright © 2010 Pearson Education, Inc. Figure 1.5 Signal wire turns heater on Signal wire turns heater off Response; temperature rises Response; temperature drops Stimulus: rising room temperature Stimulus: dropping room temperature Balance Effector (heater) Effector (heater) Set point Control center (thermostat) Heater off Set point Receptor-sensor (thermometer in Thermostat) Control center (thermostat) Heater on Imbalance Receptor-sensor (thermometer in Thermostat) Regulation of Room Temperature by a Thermostat

Copyright © 2010 Pearson Education, Inc. Figure 1.5 Sweat glands activated Shivering begins Stimulus Body temperature rises BALANCE Information sent along the afferent pathway to control center Information sent along the afferent pathway to control center Afferent pathway Afferent pathway Efferent pathway Efferent pathway Information sent along the efferent pathway to effectors Information sent along the efferent pathway to effectors Stimulus Body temperature falls Receptors Temperature-sensitive cells in skin and brain Receptors Temperature-sensitive cells in skin and brain Effectors Sweat glands Effectors Skeletal muscles Control Center (thermoregulatory center in brain) Control Center (thermoregulatory center in brain) Response Evaporation of sweat Body temperature falls; stimulus ends Response Body temperature rises; stimulus ends Regulation of Body Temperature

Copyright © 2010 Pearson Education, Inc. Pancreatic Hormones and Blood Sugar

Copyright © 2010 Pearson Education, Inc. Positive Feedback  The response enhances or exaggerates the original stimulus  May exhibit a cascade or amplifying effect  Usually controls infrequent events – Examples: Enhancement of labor contractions by oxytocin (Chapter 28) Platelet plug formation and blood clotting

Copyright © 2010 Pearson Education, Inc. Initiation of Labor

Copyright © 2010 Pearson Education, Inc. Feedback cycle ends when plug is formed. Positive feedback cycle is initiated. Positive feedback loop Break or tear occurs in blood vessel wall. Platelets adhere to site and release chemicals. Released chemicals attract more platelets. Platelet plug forms Figure 1.6 Platelet Plug Formation and Blood Clotting

Copyright © 2010 Pearson Education, Inc. Homeostatic Imbalance  Disturbance of homeostasis or the body ’ s normal equilibrium Increases risk of disease Contributes to changes associated with aging May allow destructive positive feedback mechanisms to take over (e.g., heart failure)