A&P1 CH1 Organization of the Body

Anatomy

Structure of body parts and relations

Gross

Large parts, visible to eye (what you can see)

Includes: Regional, Systemic, Surface

Microscopic

Cannot see with eye, use microscopes

Includes: Cytology (Study of Cells) & Histology (Study of Tissues)

3. Tissues

Similar cells with common function (cells that act alike and look alike).

ex. Epithelial, Connective, Muscle, Nervous

Development

Structure changes

Includes: Embryology (Developmental changes from fertilization to birth)

Physiology

Function of body, includes how parts work and associated activities.

“Function reflects structure”

1. Atoms, molecules, organelles

Not alive

2. Cell

“Where life begins”

4. Organ

Composed of more than 1 tissue

5. Organ System

Organs working together

6. Organismal

Entire organism

10 Necessary Life Functions (Characteristics of Life)

Organization, Maintaining Boundaries, Movement, Responsiveness/excitability, Digestion, Metabolism, Excretion, Reproduction, Growth, & Development

Maintaining Boundaries

So that internal environment remains distinct from the external environment.

Movement

Activities to produce action/motion.

Responsiveness/excitability

Ability to sense changes in environment and elicit response. (Response to stimuli)

Ex. Temperature increases, you start to sweat.

Digestion

Breakdown of nutrients to simple molecules for cell to use.

Metabolism

All chemical reactions in the body: catabolism and anabolism

Metabolic rate

How fast your body builds and breaks stuff down

Catabolism

Breaks down molecules to release energy.

Anabolism

Builds tissues and requires energy.

Excretion

Removal of wastes.

Ex. CO2, Urine

Reproduction

At cellular and organismal level.

Skin cells (within us, asexually)

Embryos (outside of us, sexually)

Survival Needs

Nutrients, oxygen, water, certain temperature range, certain atmospheric pressure range.

Homeostasis

Ability to maintain relatively stable internal conditions even though the outside world changes continuously.

Ex. Heart rate, blood sugar, BP, oxygen levels, temperature

3 Components of Homeostatic Control

Receptor, Control Center, Effector

Receptor

Sensor that monitors environment and responds to change in some stimulus by sending information to the control center via afferent path (taking information to the control center).

Control Center “The Brain”

Determines the set point, analyzes input, determines appropriate response, and sends information to effector via efferent path (EE “EXit” leaving to go to effector, sending a response)

Ex. It’s cold → Control Center → sends signals telling your body to shiver

Effector

Provides a means for the control center’s response.

Negative Feedback Mechanisms

Output shuts off the original effect of the stimulus or reduces its intensity after response occurs (turn off a given reaction after a certain amount).

“We don’t need anymore proteins so stop making them!”

Positive Feedback Mechanisms

The result or response enhances the original stimulus so that the response is accelerated (get a given response and you want more/response until you get the result you want).

Ex. Contractions (for labor), blood clotting

Homeostatic Imbalance w/age

The body control systems become less efficient and our internal environment becomes less and less stable.

(Body breaks down, unable to maintain BP, kidney functions, oxygen, etc.) otherwise we would live forever!

Homeostatic Imbalance w/Faulty Negative Feedback Systems

Overwhelmed by positive feedback mechanisms.

Ex. Too much blood clotting can lead to strokes and heart attacks