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 isletsOne 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 organellesOne organelle: plasma membrane
Plasma membrane: hundreds of types of moleculesOne 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
Negative Feedback:
Concentration of glucose in blood
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
Approximate normal ranges for selectedblood measurements:
Arterial pH 7.35 - 7.43Bicarbonate 21.3 - 28.5 mEq/LSodium 136-151 mEq/LCalcium 4.6 - 5.2 mEq/LOxygen 17.2 - 22 ml / 100 mlUrea 12 - 35 mg / 100 mlAmino acids 3.3 - 5.1 mg / 100 mlProtein 6.5 - 8 g / 100 mlTotal lipids 350 - 850 mg / 100 mlGlucose 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
2) In discussing parts of the human body, we also use a number of terms of relative position:
Superior (cranial): Inferior (caudal):
Superficial: Deep:
Proximal:Distal:
Anterior (ventral):Posterior (dorsal):
Medial:Lateral:
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
5) Finally: As we discuss the human body, get your brain to think three-dimensionally and focus on relationships . . .
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