1. Biology 211 Anatomy & Physiology I
Orientation
to the
Human Body

2. Throughout this course, we will focus on three "major concepts" which are central to the understanding of anatomy and physiology: a) Adaptation of anatomical structures to carry out specific physiological functions b) A "structural heirarchy" in both anatomy and physiology, from atoms to the entire organism. c) Homeostasis maintained by feedback mechanisms

3. 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
Each function is divided among many systems
and
Each system has multiple functions

4. 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

5. 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.

6. 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.

7. 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 damages the plasma membranes of oligodendrocytes so they can’t properly produce myelin, while all other organelles of these cells and all other cells remain healthy.

8. 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

9. Homeostasis involves feedback mechanisms:
Positive Feedback: When a small change occurs, the
body responds by producing a greater change
in the same direction.
Allows rapid response and magnification
Examples: Blood clotting
Immunity
Negative Feedback: When a small change occurs, the
body responds by producing change in the
opposite direction.
Causes return to the original condition
Examples: Body temperature
Blood glucose concentration

10. Positive Feedback
Blood Clotting
The body responds to a
small clot by forming
an even larger clot

11. Negative Feedback: Temperature Regulation
The body responds to an increase in temperature by
decreasing the temperature, or
The body responds to a decrease in temperature by
increasing the temperature

12. Concentration of glucose in blood
Negative Feedback:
Concentration of glucose in blood
The body responds to
an increase in blood
glucose by lowering
its concentration, or
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

13. 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
The body responds to
an increase in blood
glucose by lowering
its concentration, or
The body responds to a
decrease in blood
glucose by increasing
its concentration

14. For example, in the blood:
Negative feedback is the mechanism your body uses to keep literally thousands of things within “normal” limits (homeostasis).
For example, in the blood:
Arterial pH
Bicarbonate mEq/L
Sodium mEq/L
Calcium mEq/L
Oxygen ml / 100 ml
Urea mg / 100 ml
Amino acids mg / 100 ml
Protein g / 100 ml
Total lipids mg / 100 ml
Glucose mg / 100 ml

15. 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

16. 1) In discussing the organization of the human body and its parts, we often establish our "point of view" according to three planes or sections:
Coronal
or Frontal
Plane
Horizontal
or Transverse
Plane
Sagittal
Plane

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

20. 2) In discussing parts of the human body, we also use a number of terms of relative position:
Superior (cranial): Toward head or upper part of structure
Inferior (caudal): Toward sacrum or lower part of structure
Anterior (ventral): Toward the front
Posterior (dorsal): Toward the back
Medial: Toward the midline of the body or of a structure
Lateral: To side of midline of the body or of a structure
Proximal: Closer to center or origin
Distal: Away from center or origin
Superficial: Toward the surface of the body or of a structure
Deep: Toward the center of the body or of a structure

21. 3) Various regions of body have specific names:
Anterior

22. Various parts of body have specific names:
Posterior

23. 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
brachial
carpal
For example: The _________ region is immediately distal
to the antebracheal region

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

25. Secondary Body Cavities (Formed in place as organs develop)
Examples:
- Pericardial cavity around heart
- Pleural cavities around lungs
- Synovial cavities between bones
- Nasal cavity
- Oral cavity
- Orbital cavities
- External, Middle, and Inner ear cavities

26. 5) Finally: Positional relationships are very important, so as we discuss the human body, get your brain to think three-dimensionally and focus on those relationships . . .