Chapter 1 – Introduction to anatomy and physiology A new language

Anatomical Position  Body erect  feet slightly apart  palms facing forward  thumbs point away from body

The new language – anatomical position  The anatomical position is extremely important in studying anatomy since it is universal.  This allows professionals to easily communicate with each other, even if they are from different countries or backgrounds  Regardless of the patient body position – you ALWAYS refer to anatomical position

Other concepts you need to know if you want to speak the language (you’ll do most of it in the lab)  Body planes  Dorsal and ventral cavities  Abdominopelvic quadrants and 9 regions  Organ systems  Membranes

Overview of Anatomy and Physiology  Anatomy – the study of the structure of body parts and their relationships to one another  Gross or macroscopic – large visible body structures (heart, lungs, kidney etc.)  Different ways to approach gross anatomy:  Regional – study of all the structure in a particular region of the body (leg, abdomen etc.)  Systemic – study a particular system at a time.  Microscopic – deals with structures that are too small to be seen with the naked eye  Cytology – relates to the cells  Histology – study of the tissues  Physiology – the study of the function of the body

Specialized Branches of Anatomy  Pathological anatomy – study of structural changes caused by disease  Radiographic anatomy – study of internal structures visualized by specialized scanning procedures such as X-ray, MRI, and CT scans  Molecular biology – study of anatomical structures at a subcellular level

Keep in mind  Anatomy explains physiology  Form and function are interrelated

The function and process  Those are 2 related topics of physiology  The function of a physiological system is the “why” of a system event  Why does the system exist and why does the event happen?  Why red blood cells transport oxygen?  They do so because the cells need oxygen to survive  The process is “how”  How do the RBC transport the oxygen?  The oxygen binds to hemoglobin

The levels of organization in the body, with the four primary tissue types EXTRACELLULAR MATERIAL AND FLUIDS CELLS combine to form TISSUES combine to form ORGANS interact in ORGAN SYSTEMS EPITHELIAL TISSUE CONNECTIVE TISSUEMUSCLE TISSUE NEURAL TISSUE

Necessary Life Functions  Maintaining boundaries – the internal environment remains distinct from the external environment  Cellular level – accomplished by plasma membranes  Organismal level – accomplished by the skin

Survival Needs  Nutrients – needed for energy and cell building  Oxygen – necessary for metabolic reactions  Water – provides the necessary environment for chemical reactions (60-8% of body weight)  Normal body temperature – necessary for chemical reactions to occur at life-sustaining rates (why is it important to maintain core body temperature?)  Atmospheric pressure – required for proper breathing and gas exchange in the lungs

Some environments in our body – fluid compartments  Fluids in the body are compose of water and solutes  There are 2 distinct fluid compartments  Intracellular fluid (ICF)  The cytosol of cells  Makes up about two-thirds of the total body water  Extracellular fluid (ECF)  Major components include the plasma and lymph  Minor components include all other extracellular fluids (water in dense CT, bone, fluid between visceral and parietal membranes.)

Cations and Anions in Body Fluids

Homeostasis  Homeo – unchanging + stasis – standing  The ability to maintain a relatively stable internal environment in an ever-changing outside world  The internal environment of the body is in a dynamic state of equilibrium – it is not a precise value  Homeostatic regulation is the adjustment of physiological systems to preserve homeostasis  It happens in an environment that is inconsistent, unpredictable and at times – dangerous

Important components of homeostasis in the ECF* Normal rangeApproximate short-term nonlethal limit units Oxygen mmHg Carbon dioxide mmHg Sodium ions mmol/L Potassium ions mmol/L Calcium ions mmol/L Chloride ions mmol/L Bicarbonate ions mmol/L Glucose Mg/dl Body temperature (37.0) ( ) 0 F ( 0 C) Acid-base pH Medical Physiology – Guyton and Hall, 11 th ed.

Maintaining homeostasis involves cooperation between systems

Homeostatic imbalances  If the body fails to maintain homeostasis it may result in a disease or pathological condition  Diseases divide into 2 groups according to their origin:  Internal failure of normal physiological process  Abnormal cell growth, Production of antibodies against the body’s own tissues, Premature cell death, Inherited disorders  External sources  Toxic chemicals, Trauma, Foreign invaders

Local and long-distance control pathways  Local / autoregulation/ intrinsic control – in the cell or tissue – autocrine or paracrine mechanisms (CO 2 levels in the tissue influence diameter of local capillaries)  Long distance control/extrinsic involves the nervous and endocrine systems.  The long distance neural control involves 3 components – sensor, integration center and effector  The endocrine cells receive the stimulus directly and respond by releasing hormones (will be discussed in APII).

Homeostatic control  Some aspects of control systems:  Tonic control – maintaining “moderate activity” – example – blood vessel diameter. Tonic control is not stopping or starting activity (similar to turning radio volume louder or softer)  Antagonistic control – for systems that are not under tonic control either by hormones or the nervous system (insulin and glucagon, sympathetic and parasympathetic)

Tonic control

Homeostatic Control Mechanisms components  The three components of control mechanisms:  Sensory receptor (NOT a membrane receptor) – monitors the environments and responds to changes (stimuli)  Control center – determines the set point at which the variable is maintained  Effector – provides the means to respond to stimuli  Pathways – afferent (sensory) and efferent (motor)

Homeostatic Control Mechanisms Change detected by receptor Stimulus: Produces change in variable Input: Information sent along afferent pathway to Receptor (sensor)Effector Control center Variable (in homeostasis) Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis Output: Information sent along efferent pathway to

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)

Positive Feedback  In positive feedback systems, the output enhances or exaggerates the original stimulus  Body is moved away from homeostasis  Normal range is lost  Used to speed up processes  Positive feedback is also known as a “vicious cycle” – if not stopped can lead to death Figure 1.6

Positive feedback is NOT homeostatic process