AP Biology- Chapter 45 Hormones
Distinguish between alpha and beta cells in the pancreas and explain how their antagonistic hormones (insulin and glucagon) regulate carbohydrate metabolism
1.Alpha- release glucagon when blood sugar is too low (fasting or exercise) 2.Beta- release insulin when blood sugar is too high (carb intake
Explain what changes may be triggered by a signal transduction pathway initiated by the binding of a water-soluble hormone to a receptor in the plasma membrane of a target cell.
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List the hormones of three categories of steroid hormones produced by the gonads. Describe variations in their production between the sexes.
Androgens- Produced by testes (males) mainly testosterone and functions by helping develop male secondary sex characteristics during puberty Estrogens- Mainly estradiol; responsible for maintenance of female reproductive system and development of female sex characteristics Progestins- Mainly progesterone; function is to prepare and maintain tissues of uterus for growth and support of embryo Secretions are controlled through cascade pathways. They are synthesized by gonadotropins (FSH and LH) from the pituitary glands which is in turn controlled by the hypothalamus.
Describe several examples of invertebrate hormones that function in the control of reproduction and development
Animals can react differently when exposed to the same hormone. Many hormones have multiple effects on animals and could also have different effects on different animals. For example, tissues in animals vary in their response to adrenaline. Adrenaline causes some of the tissues to contract and others to restrict blood flow. An example of a given hormone having a different effect for a different species is thyroxine. Thyroxine helps to regulate metabolism in many animals but frogs also use thyroxine in order to help them in the resorption of the tadpole's tail to turn to adult.
Describe an example of a simple hormone pathway with negative feedback
EX} Osmoregulation of digestive tract In negative feedback, the effector response reduces the initial stimulus, and eventually the response ceases. This prevents overreaction by the system. Negative feedback regulates many endocrine and nervous mechanism
Explain the role of tropic hormones in coordinating endocrine signaling throughout the body
Follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid-stimulating hormone (TSH) are similar glycoproteins. FSH and LH are also called gonadotropins because they stimulate the activities of the gonads. TSH promotes normal development of the thyroid gland and the production of thyroid hormones. Adrenocorticotropic hormone (ACTH) is a peptide hormone that stimulates the production and secretion of steroid hormones by the adrenal cortex. signals to the brain stimulate release of an anterior pituitary tropic hormone. The tropic hormone then acts on its target endocrine tissue, stimulating secretion of a hormone that exerts systemic metabolic or developmental effects.
Describe the nature and location of intracellular receptors for hormones that pass easily through cell membranes. Explain how their role compares to the signal-transduction pathway noted above, and describe the changes they are likely to trigger within the target cell
Hormones that pass easily through the cell membrane are lipid soluble hormones. Receptors for these types of hormones are located within the cell; therefore, these hormones pass through the plasma membrane of cell in order to bind to these receptors. On the other hand, signal transduction pathways bind to receptors located on the plasma membrane in order to activate these types of reactions
List the hormones of the thyroid gland and explain their roles in development and metabolism. Explain the causes and symptoms of hyperthyroidism, hypothyroidism, and goiter.
Hyperthyroidism is caused by excessive secretion of the thyroid hormones. This causes high body temperature, profuse sweating, weight loss, irritability, and high blood pressure. Hypothyroidism results from having too little thyroid function. Symptoms include weight gain, lethargy, and intolerance to cold. Goiter results from the swelling of the thyroid gland. This results in the neck or voice box. Triiodothyronine (T3)- This helps to stimulate and maintain metabolic processes. thyroxine (T4)- (same as above) Most of the time one iodine is removed from it to produce (T3) Calcitonin- Lowers blood calcium levels
Distinguish between paracrine and autocrine signals
Local regulators are divided into two types: Paracrine signals act on cells near the secreting cell Autocrine signals act on the secreting cell itself
Define and give an example of a neurohormone
Neurohormones are a class of hormones that originate from neurons in the brain and diffuse through the bloodstream. example:
Describe the function of the positive feedback by oxytocin signaling
PICTURE ON POWERPOINT
List the three major classes of molecules that function as hormones.
Polypeptides (water soluble) Amines derived from amino acids (water soluble) Steroid hormones (lipid soluble)
List the hormones of the adrenal cortex and describe their functions.
The adrenal cortex produces the glucocorticoids and mineralocorticoids. The glucocorticoids is a steroid that raises blood glucose levels. The mineralocorticoids are steroids that promote reabsorption of Na+ and K+ in kidneys. Glucocorticoids is regulated by ACTH, Adrenocorticotropic hormone, and the mineralocorticoids are regulated by K+ in blood and angiotensin II
List the hormones of the adrenal medulla, describe their functions, and explain how their secretions are controlled.
The adrenal medulla is the central portion of the adrenal glands. This develops from neural tissues during embryonic development. The adrenal medulla produces epinephrine and norepinephrine. These hormones are created in response to stress. These hormones help create more energy by increasing the availability of energy sources in order to deal with the stress. This is controlled by neurons which send them impulses to activate whenever stress appears.
Explain how the hypothalamus and pituitary glands interact and how they coordinate the endocrine system
The hypothalamus and pituitary glands interact within the endocrine system. The hypothalamus sends signals to the pituitary glands in order for them to release these hormones. For example, if the hypothalamus sends the pituitary gland a signal to release the oxytocin hormone, then the posterior part of the pituitary gland will release it.
Note the location of the parathyroid glands and describe the hormonal control of calcium homeostasis.
The parathyroid glands are located in the posterior surface of the thyroid. This plays a major role in calcium homeostasis because of the release of parathyroid hormone (PTH). Whenever calcium blood levels fall below set point, PTH is released and raises the calcium levels in blood through direct and indirect means. Directly, PTH stimulates calcium reabsorption through the renal tubules and indirectly influences it by promoting creation of Vitamin D.
Describe the location of the pineal gland. Explain the significance of its secretion of melatonin
The pineal gland is a small mass of tissue located in the center of the brain. This gland helps secretes melatonin. Melatonin is significant because it regulates function related to light and to seasons marked by changes in daylight. Basically, it is controlled by the light/dark cycles of the seasons. If night is longer, then melatonin is released more.
Describe the location of the pituitary. List and explain the functions of the hormones released from the anterior and posterior lobes.
The pituitary gland is located at the base of the hypothalamus. Anterior growth hormones - stimulates bone growth and metabolic functions prolactin - stimulation of milk production and secretion follicle stimulating hormone - stimulation of ova and sperm luteinizing hormone - stimulates ovaries and testes thyroid stimulating hormone - stimulates thyroid gland adrenocorticotropic hormone - stimulates adrenal cortex to secrete glucocorticoids Posterior oxytocin - stimulates contraction of uterus and regulation of milk release antidiuretic hormone - promotes retention of water in kidney
Discuss how and why different target cells exposed to the same hormone may respond in diverse ways
The same hormone may have different effects on target cells that have: Different receptors for the hormone Different signal transduction pathways Different proteins for carrying out the response A hormone can also have different effects in different species
Distinguish between hormones and local regulators
chemical signals that communicate regulatory messages within the body Hormones reach all parts of the body, but only target cells are equipped to respond Local regulators are chemical signals that travel over short distances by diffusion Local regulators help regulate blood pressure, nervous system function, and reproduction
