Ch. 1 – Characteristics of Life & Organization of the Human Body

What is the difference between Anatomy and Physiology?

A. Anatomy- study of the structures of an organism -Examples of 4 subcategories:

1. Gross anatomy- large, what you can see

2. Microscopic anatomy - tiny Cytology= study of cells Histology= tissues

3. Developmental Anatomy -structure of an embryo (embryology)

4. Pathological anatomy- diseased structures

B. Physiology- study of the functions of an organism

Virtually all processes in the body occur in order to maintain Homeostasis What is Homeostasis?

Homeostasis- an organism’s maintenance of a relatively constant internal state within set ranges. Examples: Temp.= ~ 98.6 °F b.p.= ~ 120/80 mmHg glucose= ~ 90-130 mg/dl Blood pH= 7.4 hydration= ~60% H2O MANY, MANY more!

Homeostatic control mechanisms- -known as a feedback control loop -virtually all of the body’s organ systems can be involved -there are three basic components: -Sensor (or receptor) – senses a change (the “stimulus”) -Integrator, (control center) – interpret the change -Effector – produces response to the change

Example: SENSOR: pressure sensor in the walls of the heart and major arteries senses low blood pressure (stimulus) and sends a signal to the brain. INTEGRATOR: Medulla oblongata in the brain determines degree in which b.p. must be corrected and send a signal back to the heart. EFFECTOR: the heart begins to beat faster thereby increasing pressure (response).

NEGATIVE feedback loop- -creates a response that opposes the initial stimulus or change. (reverses the change) -works to stabilize physiological variables -are responsible for maintaining homeostasis

POSITIVE feedback loop- -amplifies or reinforces the change that is occurring CANCER! -can be harmful or disasterous  -a few healthy positive feedback mechanisms= childbirth, bloodclotting, sneeze

What are the levels of organization in the human body? -chemical (subatomic, atomic, molecules, macromolecules) -organelles -cells (differentiated to perform unique functions) 100 Trillion! -tissues -organs -organ system (see below) -organism (human)

11 Body Systems (see pg. 8-12) Outer Protection: Integumentary (skin) Skeletal

11 Body Systems (see pg. 8-12) Support & Movement: Skeletal Muscular

11 Body Systems (see pg. 8-12) Nervous Endocrine (glands and hormones) Communication, Control, and Integration: Nervous Endocrine (glands and hormones)

11 Body Systems (see pg. 8-12) Transportation & Defense: Cardiovascular (circulatory) Lymphatic (immune)

11 Body Systems (see pg. 8-12) Processing, Regulation, and Maintenance: Respiratory Digestive Urinary (excretory)

11 Body Systems (see pg. 8-12) Reproduction: Reproductive