Cells All organisms are made up of cells Cells have particular properties –Discrete Boundaries – each cell has a membrane –Metabolism – each cell uses energy and creates waste –Replication –Function –Communication

Hormones Provide cell communication Indirect communication – signaling (like radio). This is called endocrine activity. Direct communication. This is called paracrine activity.

Cell Properties Each cell (except sex cells) contains identical DNA. Every cell has a complete set of instructions on how to work like any other cell. Redundant Why don’t all cells operate like all other cells?

Cell Communication Certain cells have receptors so that they can receive signals from proteins. Like puzzle pieces. Hormones are proteins – each with a particular shape.

Thyroid Function Thyroid gland (T3 and T4) controls cell metabolism, i.e., how the cell uses energy. Hypothalamus monitors the secretions of the thyroid gland (T3 and T4). If levels aren’t correct, then produces TRH. Pituitary gland (area called the adenohypophysis) has TRH receptors. TRH signals pituitary to produce TSH. Thyroid gland has TSH receptors, signaling it to produce T3 and T4.

TRH TSH T3, T4 Hypothalamus Pituitary Thyroid Negative Feedback

Thyroid Function

Diabetes Cells produce energy from glucose Insulin allows glucose to get from the bloodstream into the cells Insulin is produced by the pancreas (Islets of Langerhaus) When blood sugar increases, this causes the pancreas to secrete insulin Diabetes – when body can’t make and/or use insulin

Diabetes Type I – Juvenile diabetes: Immune system attacks and destroys insulin producing cells of the pancreas Type II – Adult onset: Cells don’t respond to insulin, insulin resistance Without glucose, cells burn fat for energy which creates ketones. When ketones build up in cells, they can poison cells.

Diabetes Insulin Shock – too much insulin Neurons (i.e., your brain) also depend on glucose as their source of energy. Neurons don’t need insulin to absorb glucose When too much insulin, then cells absorb all the available glucose, leaving none for the neurons. Dizziness, speech impairment, loss of consciousness – hypoglycemic coma