What is Anatomy?

The study of the structures of the Human body and their relationship to one another.

•Shape, Color, Size, and Position are all anatomical observations.

•Gross Anatomy – The study of large structures not requiring a micorscope •Microscopic Anatomy – The study of small structures with the aid of a microscope.

What is Physiology?

The study of How the parts of the body work. •Deals with the chemistry necessary to maintain homeostasis in the human body.

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What is Homeostasis?

The bodies ability to maintain a stable internal environment despite what the external environment is like.

2 Types 1. Negative Feedback Mechanisms.

2. Positive Feedback Mechanisms.

Negative Feedback Mechanism

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The response to the stimulus causing the imbalance is to “turn off” the stimulus returning the internal environment back to stable conditions.

Ex. Normal Body Temp 98.6 °F. Infections raise body temp. Mechanism sends white blood cells to fight infection. Body temp goes back to normal.

Positive Feedback Mechanisms

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The response to the stimulus causing the imbalance is to increase the stimulus thus causing the body to be even farther away from homeostasis. Effects can be long-term.

Ex. A rupture in a blood vessel releases a chemical that makes platelets sticky. These sticky platelets attract more platelets thus forming a “platelet plug”

Positive or Negative; What do you think?

The production and release of growth hormones is controlled by the pituitary gland and hypothalamus located in the brain. Released growth hormone binds to receptors on targeted cells in the body, promoting carbohydrate metabolism, protein synthesis and fat mobilization. Growth hormone also stimulates the liver and other tissues to secrete Insulin-like Growth Factor-1 (IGF-1). IGF-1 in turn acts on its target cells, i.e., chondrocytes (cartilage cells) and myoblasts (precursors of muscle cells) to stimulate muscle and bone growth.

Afferent Pathway Receptor (Detects Change) Control Center (Brain) Efferent Pathway Effector (Initiates response from brain) Stimulus (Causes Imbalance) Homeostasis Returns

Problem #1

How is the concept of homeostasis (or its loss) related to disease and aging? Provide examples to support your reasoning.

Taken from Text page 20

Problem #2

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When we begin to become dehydrated, we usually become thirsty. Which causes us to drink fluids. On the basis of what you now know about control systems, decide whether the thirst sensation is part of a negative or positive feedback control system and defend your choice.

Taken from Text Page 20

Try This!

Obtain a Thermometer.

Determine your temperature and record it.

Walk around the track at a BRISK pace.

As soon as you complete 2 laps, take your temperature again and record it.

Continue taking your temperature every minute until it returns back to its original number.

•How long did it take for your body to reach its original temperature?

•What else did you notice as your body temperature returned to normal?

•What type of homeostatic mechanism does this represent?