Chapter 25 Hormones Power Point Lectures for Campbell

Chapter 25 Hormones Power. Point® Lectures for Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey Lectures by Chris C. Romero, updated by Edward J. Zalisko © 2010 Pearson Education, Inc.

Biology And Society: A Hormonal Fountain of Youth? • Menopause: – Typically occurs around age 50 – Is caused by decreasing levels of – Estrogen – Progesterone © 2010 Pearson Education, Inc.

• Hormone replacement therapy (HRT): – Has been used to relieve negative symptoms of menopause but – May cause increased risks of stroke and cancer • Bioidenticals are: – Synthetic human hormones – Produced by chemically modifying plant-derived hormones © 2010 Pearson Education, Inc.

HORMONES: AN OVERVIEW • Hormones are: – Regulatory chemicals that affect specific sites in the body – Produced by most plants and animals – Made by endocrine glands © 2010 Pearson Education, Inc.

• The endocrine system: – Consists of all hormone-secreting cells – Is the body’s main system for internal chemical regulation © 2010 Pearson Education, Inc.

• Endocrine cells secrete into the bloodstream hormones that: – Can affect many cells in many different body organs but – Only affect target cells, cells that have receptors for that specific hormone © 2010 Pearson Education, Inc.

Endocrine cell Membraneenclosed sacs Blood vessel Hormone molecules Target cell Adrenal glands (type of endocrine gland), which sit atop the kidneys Receptor protein Figure 25. 1

• There are two general mechanisms by which hormones trigger changes in target cells. – Water-soluble hormones trigger responses without ever entering their target cells. © 2010 Pearson Education, Inc.

Watersoluble hormone Receptor protein Target cell Plasma membrane Relay molecules Signal transduction pathway Cytoplasmic response Nucleus or Gene regulation Figure 25. 2 -3

– Lipid-soluble hormones trigger responses after entering the target cell. © 2010 Pearson Education, Inc.

Lipidsoluble hormone Target cell Plasma membrane Receptor protein Nucleus Hormonereceptor complex Gene regulation Figure 25. 3 -4

THE HUMAN ENDOCRINE SYSTEM • The human endocrine system consists of about a dozen major glands that may have: – Only endocrine functions or – Endocrine and non-endocrine functions © 2010 Pearson Education, Inc.

• The major endocrine glands in humans are spread about the human body. © 2010 Pearson Education, Inc.

Hypothalamus Pituitary gland Thyroid gland Parathyroid glands (embedded within thyroid) Adrenal glands (atop kidneys) Pancreas Ovaries (female) Testes (male) Figure 25. 4

• Hormones have a wide range of target cells and effects. © 2010 Pearson Education, Inc.

Table 25. 1

Table 25. 1 a

Table 25. 1 b

The Hypothalamus and Pituitary Gland • The hypothalamus: – Is part of the brain – Is the main control center of the endocrine system – Receives information from nerves about the: – Internal condition of the body – External environment © 2010 Pearson Education, Inc.

• The pituitary gland: – Is a pea-sized structure that hangs below the hypothalamus – Responds to signals from the hypothalamus – Secretes hormones that influence many body functions © 2010 Pearson Education, Inc.

Brain Hypothalamus Posterior pituitary Bone Anterior pituitary Figure 25. 5

• The pituitary gland consists of two parts: – The posterior pituitary: – Stores hormones – Secretes hormones made in the hypothalamus – The anterior pituitary: – Synthesizes its own hormones, such as FSH and LH – Secretes hormones directly into the blood © 2010 Pearson Education, Inc.

• The hypothalamus: – Operates through the posterior pituitary – Directs the activities of the kidneys © 2010 Pearson Education, Inc.

Hypothalamus ADH Posterior pituitary Blood vessel Anterior pituitary ADH Kidneys (ADH increases water reabsorption and prevents dehydration) Figure 25. 6

• The anterior lobe of the pituitary also secretes growth hormone (GH), which: – Promotes development and enlargement of all parts of the body – Can lead to: – Dwarfism, if too little GH is produced – Gigantism, if too much GH is produced © 2010 Pearson Education, Inc.

(a) Overproduction of GH during development (b) Overproduction of GH during adulthood (c) Underproduction of GH during development Figure 25. 7

• Endorphins: – Are produced by the anterior pituitary – Act as natural painkillers © 2010 Pearson Education, Inc.

The Thyroid and Parathyroid Glands • The thyroid gland, located in the neck just under the larynx, produces: – Calcitonin, which lowers calcium levels in the blood – Several hormones involved in controlling: – Oxygen consumption – Metabolism – Development © 2010 Pearson Education, Inc.

• Hypothyroidism: – Results from too little thyroid hormone in the blood – Can result from: – Dietary deficiencies of iodine – A defective thyroid gland © 2010 Pearson Education, Inc.

• Hyperthyroidism – Results from too much thyroid hormone in the blood – Can lead to: – Overheating – Profuse sweating – High blood pressure – Protruding eyeballs © 2010 Pearson Education, Inc.

• The parathyroid glands: – Are four disk-shaped glands embedded within the thyroid – Produce parathyroid hormone, which raises calcium levels in the blood © 2010 Pearson Education, Inc.

• Calcitonin and parathyroid hormone (PTH) are antagonistic hormones, because they have opposite effects on calcium levels in the blood. Blast Animation: Signaling: Endocrine © 2010 Pearson Education, Inc.

Calcitonin Thyroid gland releases calcitonin Stimulates Ca 2+ deposition in bones Reduces Ca 2+ uptake in kidneys Ca 2+ level in blood falls to set point Stimulus: Rising blood Ca 2+ level (imbalance) Ca 2+ level Homeostasis: Normal blood calcium level Ca 2+ level Stimulus: Falling blood Ca 2+ level (imbalance) Ca 2+ level in blood rises to set point Parathyroid glands release parathyroid hormone (PTH) Stimulates Increases + 2 Ca release Ca 2+ uptake from bones in kidneys Increases Ca 2+ uptake in intestines PTH Parathyroid gland Figure 25. 8 -6

The Pancreas • The pancreas produces two antagonistic hormones that play important roles in managing the body’s energy supplies: – Insulin reduces blood sugar levels – Glucagon increases blood sugar levels © 2010 Pearson Education, Inc.

Body cells take up more glucose Insulin Pancreas releases insulin into the blood Liver takes up glucose and stores it as glycogen Stimulus: Rising blood glucose level (for example, after eating a carbohydrate-rich meal) Blood glucose level falls to a set point; stimulus for insulin release diminishes Glucose level Homeostasis: Normal blood glucose level Glucose level Blood glucose level rises to set point; stimulus for glucagon release diminishes Stimulus: Declining blood glucose level (for example, after skipping a meal) Pancreas releases glucagon into the blood Liver breaks down glycogen and releases glucose to the blood Glucagon Figure 25. 9 -6

• Diabetes mellitus is a hormonal disease in which body cells are unable to absorb glucose from the blood either because: – There is not enough insulin produced (type 1, or insulin-dependent diabetes) or – The target cells do not respond normally to insulin (type 2, or non-insulin -dependent diabetes) • Diabetes can be treated. © 2010 Pearson Education, Inc.

Figure 25. 10

The Adrenal Glands • The adrenal glands are paired structures resting atop the kidneys. • Each adrenal gland consists of two glands: – The adrenal medulla – The adrenal cortex © 2010 Pearson Education, Inc.

• The adrenal medulla secretes epinephrine and norepinephrine, hormones that: – Enable the body to respond to stress – Produce the fight or flight response © 2010 Pearson Education, Inc.

• Stressful stimuli activate nerve cells in the hypothalamus that send signals to stimulate the adrenal medulla. © 2010 Pearson Education, Inc.

• The adrenal cortex: – Is also stimulated by the hypothalamus – Secretes two hormones that provide a slower, longer-lasting response to stress: – Corticosteroids – Glucocorticoids Blast Animation: Signaling via Steroid Hormones © 2010 Pearson Education, Inc.

STRESS Adrenal medulla Adrenal gland Adrenal cortex Kidney Nerve signals Hypothalamus Releasing hormone Nerve cell Spinal cord (cross section) Nerve cell Anterior pituitary Blood vessel ACTH Adrenal medulla Epinephrine and norepinephrine Short-term stress response 1. Glycogen broken down to glucose; increased blood glucose 2. Increased blood pressure, breathing rate, heart rate, and metabolic rate 3. Change in blood flow patterns, leading to increased alertness and decreased digestive activity Adrenal cortex ACTH Corticosteroids Long-term stress response 1. Proteins and fats broken down and converted to glucose, leading to increased blood glucose 2. Immune system may be suppressed Figure 25. 11

The Gonads • The gonads secrete sex hormones that: – Affect growth and development – Regulate: – Reproductive cycles – Sexual behavior © 2010 Pearson Education, Inc.

• Males and females have the same three types of sex hormones: – Estrogens – Progestins – Androgens © 2010 Pearson Education, Inc.

• Estrogens: – Maintain the female reproductive system – Promote the development of specific female features © 2010 Pearson Education, Inc.

• Progestins, including progesterone, are primarily involved in preparing the uterus to support a developing embryo. © 2010 Pearson Education, Inc.

• Androgens, including testosterone, stimulate the development and maintenance of the male reproductive system. © 2010 Pearson Education, Inc.

The Process of Science: Can Pollution Cause Sex Changes? • Observation: All of the female mosquitofish collected in a Florida stream had anatomical features and behaviors normally found only in males. • Question: Was pollution from a nearby paper mill the cause of these changes? • Hypothesis: Runoff from the mill contained endocrine disruptors. © 2010 Pearson Education, Inc.

• Experiment: Water and fish were analyzed from above and below the paper mill. • Results: Female fish with masculine features were found only downstream of the paper mill. © 2010 Pearson Education, Inc.

Paper mill discharging waste water C re ek Contaminated sample sites Uncontaminated sample sites Normal female Female with male organ Eleve n Mile Normal male Perdido Bay Figure 25. 12