Chapter 1: Introduction to Anatomy and Physiology

For the first lecture test, I should be able to… A. Define anatomy and physiology. 1. Explain how they are related. 2. Describe major specialties of each. B. Define homeostasis and explain its importance for survival. 1.Compare/contrast intrinsic and extrinsic regulation and provide an example of each. 2.Compare/contrast negative and positive feedback and provide an example of each. 3.Discuss the relationship between homeostasis and disease.

Anatomy Physiology Describes the structures of the body What they are made of Where they are located Associated structures Physiology Is the study of: Functions of anatomical structures Individual and cooperative functions Biochemistry, Biology, Chemistry, Genetics

Relationships between Anatomy and Physiology Gross anatomy, or macroscopic anatomy, examines large, visible structures Surface anatomy: exterior features Regional anatomy: body areas Systemic anatomy: organ systems Developmental anatomy: from conception to death Clinical anatomy: medical specialties

Relationships between Anatomy and Physiology Microscopic anatomy examines cells and molecules Cytology: study of cells and their structures cyt- = cell Histology: study of tissues and their structures

1-4 Relationships between Anatomy and Physiology Cell physiology: processes within and between cells Organ physiology: functions of specific organs Systemic physiology: functions of an organ system Pathological physiology: effects of diseases

1-5 Levels of Organization The Chemical (or Molecular) Level Atoms are the smallest chemical units Molecules are a group of atoms working together The Cellular Level Cells are a group of atoms, molecules, and organelles working together The Tissue Level A tissue is a group of similar cells working together The Organ Level An organ is a group of different tissues working together

1-5 Levels of Organization The Organ System Level An organ system is a group of organs working together Humans have 11 organ systems The Organism Level A human is an organism

Figure 1-1 Levels of Organization Cellular Level Chemical and Molecular Levels Heart muscle cell Protein filaments Complex protein molecule Atoms in combination 9

Figure 1-1 Levels of Organization Organism level Organ system level Organ Level Tissue Level Cardiac muscle tissue The heart The cardiovascular system 10

KEY CONCEPT The body is divided into 11 organ systems All organ systems work together Many organs work in more than 1 organ system

1-6 Homeostasis Homeostasis All body systems working together to maintain a stable internal environment Systems respond to external and internal changes to function within a normal range (body temperature, fluid balance)

1-6 Homeostasis Mechanisms of Regulation Autoregulation (intrinsic) Automatic response in a cell, tissue, or organ to some environmental change Extrinsic regulation Responses controlled by nervous and endocrine systems

1-6 Homeostasis Receptor Control center Effector Receives the stimulus Processes the signal and sends instructions Effector Carries out instructions CONTROL CENTER

Figure 1-2 The Control of Room Temperature RECEPTOR Information affects Normal condition disturbed Thermometer STIMULUS: Room temperature rises HOMEOSTASIS CONTROL CENTER (Thermostat) Air conditioner turns on Air conditioner turns off Normal room temperature RESPONSE: Room temperature drops 20° 30° 40° Room temperature (°C) Normal range 22 Normal condition restored EFFECTOR Sends commands to Air conditioner turns on Time In response to input from a receptor (a thermometer), a thermostat (the control center) triggers an effector response (either an air condi- tioner or a heater) that restores normal temperature. In this case, when room temperature rises above the set point, the thermostat turns on the air conditioner, and the temperature returns to normal. With this regulatory system, room temperature fluctuates around the set point. 15

1-7 Negative and Positive Feedback The Role of Negative Feedback The response of the effector negates the stimulus Body is brought back into homeostasis Normal range is achieved

Figure 1-3 Negative Feedback in the Control of Body Temperature RECEPTORS Temperature sensors in skin and hypothalamus Information affects Normal temperature disturbed CONTROL CENTER STIMULUS: Body temperature rises HOMEOSTASIS Thermoregulatory center in brain Normal body temperature Vessels dilate, sweating increases Vessels constrict, sweating decreases RESPONSE: Increased heat loss, body temperature drops 37.2 Normal temperature restored EFFECTORS Sends commands to Body temperature (°C) Normal range 37 • Sweat glands in skin increase secretion • Blood vessels in skin dilate 36.7 Time Events in the regulation of body temperature, which are comparable to those shown in Figure 12. A control center in the brain (the hypothalamus) functions as a thermostat with a set point of 37°C. If body temperature exceeds 37.2°C, heat loss is increased through enhanced blood flow to the skin and increased sweating. The thermoregulatory center keeps body temperature fluctuating within an acceptable range, usually between 36.7 and 37.2°C. 17

1-7 Negative and Positive Feedback The Role of Positive Feedback The response of the effector increases change of the stimulus Body is moved away from homeostasis Normal range is lost Used to speed up processes

Figure 1-4 Positive Feedback: Blood Clotting Wouldn’t you want to speed this up? Clotting accelerates Positive feedback loop Chemicals Chemicals Blood clot Damage to cells in the blood vessel wall releases chemicals that begin the process of blood clotting. The chemicals start chain reactions in which cells, cell fragments, and soluble proteins in the blood begin to form a clot. As clotting continues, each step releases chemicals that further accelerate the process. This escalating process is a positive feedback loop that ends with the formation of a blood clot, which patches the vessel wall and stops the bleeding. 19

1-7 Negative and Positive Feedback Systems Integration Systems work together to maintain homeostasis Homeostasis is a state of equilibrium Opposing forces are in balance Dynamic equilibrium — continual adaptation Physiological systems work to restore balance Failure results in disease or death