PhysioEx 28B

PhysioEx 28B Worksheet Include in lab report 1

Metabolism Metabolism – broad term for all chemical reactions occurring in the body Involves catabolism Process of breaking down complex substances into simple substances Releases stored energy when bonds are broken in large molecules Involves anabolism Enzymes build up smaller molecules into more complex molecules Energy is stored when molecules are made Energy is either stored as adenosine triphosphate (ATP) or given off as body heat

Hormones Throxyine Most important hormone in maintaining body temperature and metabolism Found in thyroid Controlled by the pituitary gland Secretes thyroid-stimulating hormone (TSH). TSH Carried by the blood to the thyroid gland and causes the thyroid to produce more thyroxine

PhysioEx 28B Go to “exercise” → “endocrine system physiology” Complete exercises: - Metabolism - Hormone Replacement Therapy - Insulin and Diabetes Part I - Insulin and Diabetes Part II - Measuring Cortisol and Adrenocorticotrophic Hormone

Determining Baseline Metabolic Rates You will investigate the effects of thyroxine and TSH on an animal’s metabolic rate (see Figure 28B.1b). To begin, select Exercise 28B: Endocrine System Physiology from the drop-down menu and click GO. Before you perform the activities, watch the BMR Measurement video. To see an experiment in which basal metabolic rate is measured. Then click Metabolism. The opening screen will appear in a few seconds (see Figure 28B.1a). Select Balloons On/Off from the Help menu for help identifying the equipment onscreen (you will see labels appear as you roll the mouse over each piece of equipment). Select Balloons On/Off to turn this feature off before you begin the experiments. Complete Activity 1 and Chart 1.

Hormone Replacment Therapy Follicle-stimulating hormone (FSH) stimulates ovarian follicle Produces estrogen Menopause = hormone production is stopped Results in loss of bone density, which can result in osteoporosis and bone fractures Estrogen is used as postmenopausal treatments to prevent osteoporosis Calcitonin = hormone that inhibits osteoclast activity and stimulates calcium uptake for deposit in bone. In this experiment we will use three ovariectomized rats because they are no longer producing estrogen due to the removal of their ovaries. You will administer either estrogen therapy or calcitonin therapy, two types of hormone replacement therapy to obtain T-scores. T scores are interpreted as follows: normal 1 to 0.99; osteopenia (bone thinning) 1.0 to 2.49; osteoporosis 2.5 and below.

Insulin and Diabetes Insulin is produced by the beta cells of the endocrine portion of the pancreas. Helps regulate blood glucose levels How? Enables the body’s cells to absorb glucose from the bloodstream (see Figure 28B.4b). Type 1 diabetes mellitus results When insulin is not produced by the pancreas. When insulin is produced by the pancreas but the body fails to respond to it, type 2 diabetes mellitus results. In either case, glucose remains in the bloodstream, unable to be taken up by the body’s cells to serve as the primary fuel for metabolism.

Insulin and Diabetes Part 1 – Glucose Standard Curve The following experiment is divided into two parts. In Part I, you will obtain a glucose standard curve, which will be explained shortly.

Insulin and Diabetes Part II – Measuring Plasma Glucose Levels In Part II, you will use the standard curve to measure fasting plasma glucose levels in patients to diagnose diabetes mellitus.

Measuring Cortisol and Adrenocorticotrophic Hormone

Measuring Cortisol and Adrenocorticotrophic Hormone Hormone secreted by the adrenal cortex Function: Regulates stress Adrenocorticotropic hormone (ACTH), stimulates its release ACTH produce in anterior pituitary Corticotropin-releasing hormone (CRH) stimulates its release Increased levels of cortisol negatively feed back to inhibit the release of both ACTH and CRH. See Figure 28B.5b for the regulation of cortisol secretion. Hypercortisolism (Cushing’s syndrome or disease if it is due to an adrenal tumor) is increased cortisol in the blood Hypocortisolism can occur due to adrenal insufficiency. Addison’s disease - primary adrenal insufficiency in which the low cortisol is directly due to gradual destruction of the adrenal cortex, and ACTH levels are typically elevated as a compensatory effect.

Cortisol and ACTH Disorders

Measuring Cortisol and Adrenocorticotropic Hormone Start by selecting Measuring Cortisol and Adrenocorticotropic Hormone from the Experiment menu. A new screen will appear (Figure 28B.5a) with five patient plasma samples and an HPLC (high-performance liquid chromatography) column that will be used to simulate the measurement of cortisol and adrenocorticotropic hormone (ACTH). There is a syringe that will be used to inject the samples into the HPLC injector for analysis. The Cortisol and ACTH buttons are used to prepare the column with solvents used to separate the two different hormones. The detector will measure the amount of the hormone and convert it into a concentration value.