Biology 211 Anatomy & Physiology I Orientation to Anatomy

Throughout this course, we will focus on three "major concepts" which are central to the understanding of anatomy and physiology: a) b) c)

First major concept: All complex animals share a number of basic physiological functions for which anatomical structures are specifically adapted, including: - Protection of internal body environment from external environment - Maintenance of stable internal environment - Responsiveness - Ingestion, digestion, elimination - Metabolism - Excretion - Reproduction

Second major concept: The structures and functions of all complex animals are based on a “structural heirarchy” These are interdependent. Abnormalilties at one level will affect all higher levels

Example #1: Your body consists of trillions of cells of at least 400 different types About a dozen types: Lymphocytes One type of lymphocyte: CD4 cell Suppose a virus attacks and destroys your CD4 cells, while all other cells (including all other lymphocytes) remain healthy.

Example #2: Your body consists of trillions of cells of at least 400 different types Four types found in pancreatic islets One type of islet cell: beta cell, which produces insulin Suppose your body attacks and destroys the beta cells, while all other cells (including other islet cells) remain healthy.

Example #3: Your body consists of trillions of cells of at least 400 different types One type of cell in nervous system: oligodendrocyte Oligodendrocytes: dozens of organelles One organelle: plasma membrane Plasma membrane: hundreds of types of molecules One type of molecule: myelin Suppose your body attacks and destroys the myelin in the plasma membranes of oligodendrocytes, while all molecules and all other cells remain healthy.

Third major concept: Homeostasis: A state of "dynamic (changing) equilibrium (balance)" in which the body's internal environment is maintained within narrow limits even when the external environment changes significantly. For example: You must maintain a steady internal body temperature of approximately 37oC even if the external temperature changes from -20oC to over 100oC. Homeostasis requires communication among many different organelles, cells, tissues, and organs

Homeostasis involves feedback mechanisms: Positive Feedback: Examples: Negative Feedback: Examples:

Positive Feedback Blood Clotting

Negative Feedback: Temperature Regulation

Eating increases blood glucose. Blood glucose stimulates pancreatic islets to secrete insulin. Insulin stimulates muscle cells and liver cells to absorb glucose from blood. Absorption of glucose by liver & muscle lowers its concentration in blood. This returns blood glucose to original level Negative Feedback: Concentration of glucose in blood

Fasting lowers blood glucose. Blood glucose stimulates pancreatic islets to secrete glucagon. Glucagon stimulates muscle cells and liver cells to release glucose back into blood. Release of glucose by liver & muscle increases its concentration in blood. This returns blood glucose to original level Negative Feedback: Concentration of glucose in blood

Approximate normal ranges for selected blood measurements: Arterial pH 7.35 - 7.43 Bicarbonate 21.3 - 28.5 mEq/L Sodium 136-151 mEq/L Calcium 4.6 - 5.2 mEq/L Oxygen 17.2 - 22 ml / 100 ml Urea 12 - 35 mg / 100 ml Amino acids 3.3 - 5.1 mg / 100 ml Protein 6.5 - 8 g / 100 ml Total lipids 350 - 850 mg / 100 ml Glucose 75 - 110 mg / 100 ml

Next: A few basic concepts of anatomy which we will use throughout this course 1) Planes or sections 2) Terms indicating relative positions 3) Regions of the body 4) Primary and secondary body cavities 5) Three-dimensional relationships

1)

How a structure appears depends on the plane in which you view it:

2) In discussing parts of the human body, we also use a number of terms of relative position: Superior (cranial): Inferior (caudal): Anterior (ventral): Posterior (dorsal): Medial: Lateral: Proximal: Distal: Superficial: Deep:

3) Various regions of body have specific names: Anterior

Various parts of body have specific names: Posterior

You should be able to identify the regions shown on these diagrams. For example: The region of the upper limb between the shoulder and elbow is the_________ region For example: The _________ region is immediately distal to the antebracheal region

4) Primary Body Cavities (Formed by folding of the embryo)

Secondary Body Cavities (Formed in place as organs develop) Examples: -

5) Finally: As we discuss the human body, get your brain to think three-dimensionally and focus on relationships . . .