Science Focus Topic 6 Notes: Body Systems in Humans | Print |

The Digestive System

Food enters your body through the mouth and then passes to the stomach and intestines.  It is broken down along the way into usable, soluble particles that can be used by different cells.  (Figure 2.26)

The Respiratory System

Breathing (the exchange of gases) moves air in (inhalation) and out (expiration) of our bodies.  (Figure 2.27)

The Circulatory System

Transports food and gases throughout our body (Figures 2.28 and 2.29)

How the Respiratory and Circulatory Systems Connect

The respiratory system exchanges oxygen and carbon dioxide, while the circulatory system transports those gases throughout the body.

The interaction between these two systems happens in the tissues of the lungs

Diffusion occurs between the alveoli (tissues of the respiratory system) and the capillaries (tissues of the circulatory system)

Oxygen goes from the alveoli to the capillaries and carbon dioxide goes from the capillaries to the alveoli

How the Digestive and Circulatory Systems Connect

The transfer of food particles, from the digestive system to the circulatory system, takes place at the inner lining of the small intestine, through millions of tiny, finger-like projections, called villi, which contain a network of capillaries. The transfer of food particles is possible because of absorption (the villi absorb the food particles from the capillaries and then transport the nutrients to the cells, to be used as fuel).

The Excretory System

Filters waste materials from the blood. (A Power Point Presentation on the Excretory System)

The Sensory Awareness System

Allows each of the systems of the body to respond to changing conditions and make adjustments in order to maintain a stable internal environment, allowing the cells to function properly.

-  Quivering muscles generate heat

-  90% of heat loss is through the skin (most of the rest is through the lungs)

-  Hairs on the skin stand on end when the tiny muscle cells near the surface contract, creating ? gooseflesh ? (goosebumps)

- Fluffing body hair (in animals with thick fur) reduces heat loss by improving insulation

- Feeling flushed (red and hot) happens because tiny blood vessels in the skin expand, which increases blood flow

- Sweating helps cool down your body as moisture evaporates from the skin surface

The nervous system helps to keep your body temperature stable by monitoring conditions outside, using temperature receptors in the skin.  The information is then transmitted to the hypothalamus (section of the brain which regulates body functions) which then decides what action needs to be taken ? increasing activity to raise the temperature or, reduce it to prevent heat loss.

Response to stimuli is co-ordinated by the nervous system (brain, spinal cord and nerves) and the endocrine system (glands that produce hormones).

Diet, exercise, drugs, injury and disease can affect body systems and how they perform their functions.

Summary Chart (Table 2.1 ? Page 153)