Introduction to Anatomy and Physiology


Levels of Organization:


Smallest --------------------------------------------------------------> Largest

Atoms --> Molecules --> Organelles --> Cells --> Tissues --> Organs --> Organ System --> Organism

Requirements for Human Life:


Oxygen
Water
Food
Temperature
Pressure

Homeostatic Regulation:

Homeostasis refers to a stable internal environment. Almost all the systems of the body (sorry reproductive) have the primary function of maintaining homeostasis.

Homeostatic regulation usually occurs through a receptor (a cell that picks up a signal) activating a control center (this processes the signal from the receptor) which then may activate an effector (a cell that sends a signal that changes the functioning of the body).

Negative Feedback:

An attempt to maintain homeostasis by returning a requirement for life back to its set point. For example, its very hot outside (environmental stimulus) so your body temperature rises (requirement for life moving away from its set point). Cells detect this (receptors) and the brain process that information (control center). The brain activates neurons to the skin (effector) which causes sweat to be produced and released (corrective mechanism activated). This sweat evaporates and lowers the elevated body temperature (requirement for life moving back to set point) which causes receptors to send signals to the control center which activates effectors to stop sweating (corrective mechanisms switched off).

external image nfeedback.gif
http://www.freethought-forum.com/images/anatomy/nfeedback.gif

Positive Feedback:

Occurs less frequently than negative feedback, is a temporary measure to move away from homeostasis. It functions by moving a requirement of life away from the set point. This movement away from the stimulus reinforces the mechanism moving the set away from the stimulus. Positive feedback is usually used to quickly correct a potentially life-threatening situation. If positive feedback is allowed to continue unchecked by negative feedback; death may result.

external image an-example-of-a-positive-feedback-loop-warming-leads-to-a-decrease-in-sea-ice-cover-which-in-turn-le.jpeg
http://politicalclimate.files.wordpress.com/2010/07/an-example-of-a-positive-feedback-loop-warming-leads-to-a-decrease-in-sea-ice-cover-which-in-turn-le.jpeg

A human example of this occurs during labor (during child birth). The baby's head pushes on the cervix of the mother. This sends a signal to the fundus of the uterus (the top) to contract its muscles and push harder. The baby is forced against the cervix harder which causes more rapid messages to the fundus of the uterus to push harder. The contractions get stronger and stronger until the baby is born, at which point negative feedback kicks in and lessens the contractions to prevent permanent damage to the muscles of the uterus.

Surface Anatomy

You must know the following body locations! (Found on page 17 of our text)
Frontalexternal image 1.jpg
Ocular
Otic
Nasal
Cervical
Thoracic
Mamma
Abdomen
Ubilicus
Pelvis
Manual
Pubis
Femoral
Pedal
Digits
Patella
Carpus
Brachium
Axilla
Oris
Cephalon
Facial
Cranium
Gluteus
Lumbar
Dorsum

Anatomical Directions

external image directional1_352151753.jpg
Anterior -- Posterior
Ventral -- Dorsal
Superior -- Inferior
Medial -- Lateral
Proximal -- Distal
Superficial -- Deep

Sectional Anatomy


external image plan.jpg

Body Cavities

1) Protect organs (brain, heart)
2) Allow organs to change in size and shape (lungs, heart, uterus, stomach)

We have two main body cavities:
Dorsal- contains the brain and spine is uninterrupted.
Ventral- divided into a thoracic cavity (with heart and lungs) and an abdominopelvic cavity (contains stomach, intestines, kidneys, etc.) by the diapraghm.