Chapter 3 - Chapter 3: The Human Body: Are We Really What...

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Chapter 3: The Human Body: Are We Really What We Eat? Why Do We Want to Eat What We Want to Eat? Hunger: a physiologic drive for food that occurs when the body senses that we need to eat. Non-specific Appetite: a psychological desire to consume specific foods Anorexia: an absence of the appetite even with a physiological need for food The Hypothalamus Prompts Hunger in Response to Various Signals Region of brain tissue that is responsible for prompting us to seek food Triggers feelings of hunger or satiation (fullness) by integrating signals from nerve cells and chemicals throughout our bodies Role of Nerve Cells Signal comes from special cells lining the stomach and small intestine that detect changes in pressure according to whether the organ is empty or distended with food Role of Hormones Chemical messengers that are secreted into the blood-stream by one of the many glands of the body Presence in the blood helps regulate one or more body functions Glucose is our bodies’ most readily available fuel supply The Role of Amount and Type of Food Foods containing protein have the highest satiety value High-fat diets have a higher satiety value than high-carb diets Bulky meals tend to stretch the stomach and small intestine Beverages tend to be less satisfying than semisolid foods, and semisolid foods have a lower satiety value than solid foods. Environmental Cues Trigger Appetite Role of Sensory Data Role of Social and Cultural Cues Role of Learning Are We Really What We Eat? Atoms Bond to Form Molecules Atoms are tiny units of matter than cannot be broken down by natural means Food is Composed of Molecules Molecules Join to Form Cells Cells are the smallest unit of matter that exhibits the properties of living things, such as growth, reproduction, and metabolism. Cells Are Encased in a Functional Membrane Cell membrane – the boundary of an animal cell that separates its internal cytoplasm and organelles from the external environment Defines the cells boundaries: o Encloses the cell’s contents and acts as a gatekeeper o Either allowing or denying the entry and exit of molecules such as nutrients and wastes o Selectively permeable – allowing only some compounds to enter and leave the cells
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Chapter 3: The Human Body: Are We Really What We Eat? Cells Contain Organelles That Support Life o Cytoplasm – the interior of an animal cell, not including its nucleus o Organelle – a tiny “organ” within a cell that performs a discrete function necessary to the cell. o In terms of nutrition, the most important are: (a) Nucleus – genetic info, in the form of DNA, is located (b) Ribosomes – instructions from DNA to assemble proteins (c) Endoplasmic Reticulum (ER) – proteins assembled on the ribosomes enter this network of channels and are further processed and packaged for transport (c.i) Breakdowns lipids (c.ii)
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Chapter 3 - Chapter 3: The Human Body: Are We Really What...

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