15e_Chap013_Chapter_Assessments-Study guide.docx - Copy

\ Chapter 13

Endocrine System-Study guide

\ \ 13.1 General Characteristics of the Endocrine System

1. Contrast the definitions of endocrine gland and exocrine gland.

The contrast in definition between the endocrine and exocrine gland is that the endocrine gland carries out internal secretions of the human body through the bloodstream while exocrine carries these hormones or processes through ducts or tubes to the surface.

\ 2. Explain the specificity of a hormone for its target cell.

A hormone is a secretion that affects the functions of other cells. A target cell is a cell that has a specific receptor for a certain hormone. So a hormone affects only its specific target cell.

glandular cells (where hormones are released)—---> blood stream —-> blood cells have receptors (Ex. Glycoprotein receptors) (makes it a target cell) —-> Hormones reach their target cell and act on that specific cell.

3. List six general functions of hormones.

help regulate metabolic processes.

control rates of certain chemical reactions.

aid in transporting substance through membranes.

help regulate water balance and electrolyte balance.

have a role in reproduction, development, and growth.

help regulate blood pressure.

\ 13.2 Hormone Action

4. Explain how hormones can be grouped on the basis of their chemical composition.

\ Hormones are chemicals produced by endocrine glands, which travel through the bloodstream and affect the functions of target tissues or organs. Chemically, hormones may be classified into two groups- steroids and nonsteroids. Steroid hormones are lipids, made from cholesterol and secreted by the adrenal cortex (aldosterone and cortisol), by testes (testosterone) and ovaries (estrogens). Nonsteroid hormones are a class of hormones that are primarily derived from proteins. Nonsteroids include amines, peptides, proteins, and glycoproteins. Amines (norepinephrine and epinephrine) are hormones derived from the amino acid tyrosine and synthesized in the adrenal medulla. Long chains of amino acids, linked into specific molecular structures make protein hormones (PTH, PRL). Parathyroid gland and anterior pituitary gland secrete protein hormones. Glycoproteins (FSH, LH, TSH) are a group of hormones consisting of carbohydrates jointed to proteins, secreted by the anterior pituitary gland. Short chains of amino acids synthesize the peptide hormones. The posterior pituitary gland and hypothalamus secrete peptide hormones (ADH, TRH).

5. List the steps of steroid hormone action.

(1) enters. the hormone enters the cell.
(2) receptor protein. hormone binds with receptor protein molecules inside the cell.
(3) nucleus. The hormone-receptor complex enters the nucleus.
(4) chromatin DNA protein complex. …
(5) triggers mRNA production. …
(6) specific protein

\ 6. List the steps of the action of most nonsteroid hormones.

\ 1. A nonsteroid hormone reaches a target cell

2. Nonsteroid hormones bind receptor molecules on the cell membrane

3. Hormone binding activates molecules of adenylate cyclase

4. Adenylate cyclase catalyzes conversion of ATP into cyclic adenosine monophosphate (cAMP)

5. cAMP activates existing proteins, causing a series of reactions leading to the cellular changes associated with the hormone's action

7. Explain how prostaglandins are similar to hormones and how they are different.

Unlike most hormones, which are produced by glands and transported in the bloodstream to act on distant areas of the body, the prostaglandins are produced at the site where they are needed. Prostaglandins are produced in nearly all cells and are part of the body's way of dealing with injury and illness.

13.3 Control of Hormonal Secretions

8. Diagram the three mechanisms that control hormone secretion, including negative feedback in each mechanism.

In the negative feedback system, an endocrine gland or controlling system is sensitive to the concentration of substances it regulates or of a product it controls. When the concentration increases to a certain level, the gland is inhibited (a negative effect), and its activity decreases. When the concentration decreases to a certain level, the gland is no longer inhibited and its production increases. The rapid response of this system keeps hormone levels relatively stable.

Mechanisms include:

1. Control of anterior pituitary gland secretions by the hypothalamus.

2. Stimulation of some glands directly by the nervous system.

3. Direct response by other glands to changes in the composition of the internal environment

13.4 Pituitary Gland

9. Describe the location and structure of the pituitary gland.

\ is about one centimeter in diameter and is attached to the hypothalamus at the base of the brain by the infundibulum. It is surrounded and protected by the sella turcica of the sphenoid bone. The pituitary gland is divided into two distinct lobes: the anterior (adenohypophysis) and the posterior (neurohypophysis).

\ 10. List the hormones that the anterior pituitary secretes.

secretes growth hormone (GH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL).

\ 11. Explain two ways that the brain controls pituitary gland activity.

The posterior lobe of the pituitary responds to nerve impulses from the hypothalamus. Primarily the releasing hormones from the hypothalamus control the anterior lobe of the pituitary. It does this by sending the releasing hormones in the blood through a capillary network in the hypothalamus, which merges to form the hypophyseal portal veins. It passes downward into the capillary network in the anterior lobe. Substances released from the hypothalamus are sent directly to the anterior lobe.

12. Releasing hormones come from which one of the following?

hypothalamus

13. Match the following hormones with their actions (the choices from the list on the right may be used more than once): A. milk synthesis, B. cell division, C. metabolic rate, D. acts on gonads, E. controls secretion of adrenal cortical hormones

1. growth hormone- b. cell division

2. thyroid stimulating hormone- c.metabolic rate

3. prolactin a. milk synthesis

4. adrenocorticotropic hormone- e.controls secretion of adrenal cortical hormones.

5. follicle-stimulating hormone – D. acts on gonads

6. luteinizing hormone – D. acts on gonads

\ 14. Explain how growth hormone produces its effects.

Growth hormone (GH), or somatotropin (STH), is a protein that causes cells to increase in size and mitotic rate. It increases protein synthesis and amino acid movement through cell membranes. GH also increases cellular respiration of fats by decreasing metabolism of carbohydrates.

\ 15. Describe the control of growth hormone secretion.

Growth hormone is especially secreted during sleep, and during low blood concentrations of proteins and glucose.

\ 16. Describe the anatomical differences between the anterior and posterior lobes of the pituitary gland.

The anterior lobe is composed of layers of epithelial tissues grouped around many blood vessels. The epithelial tissues contain five types of secretory cells responsible for hormone production: mammatropes, somatotropes, thyrotropes, corticotropes, and gonadotropes. The posterior pituitary lobe is made of pituicytes and nerve fibers originating in the hypothalamus.

17. Name and describe the functions of the posterior pituitary hormones.

Antidiuretic hormone (ADH)—ADH is a short polypeptide that inhibits water excretion from the kidneys.ADH can also have a contracting effect on blood vessels. This can cause a rise in blood pressure. This is especially important in cases of severe blood loss, when ADH is needed to help increase vascular resistance. For this reason, ADH is sometimes called vasopressin.

Oxytocin (OT)—OT is a short polypeptide that is responsible for uterine contractions of labor in childbirth and contracting cells of milk glands in lactating breasts so that milk is forced out during suckling. To a lesser extent, OT can play a role in antidiuretic mechanisms.

18. Under which of the following conditions would you expect an increase in antidiuretic hormone secretion?

an individual is rescued after three days in the without food or water

13.5 Thyroid Gland

19. Describe the location and structure of the thyroid gland.

The thyroid gland consists of two large lobes connected by a broad isthmus. It is found just inferior to the larynx, bilaterally and anterior to the trachea. It is a vascular structure encapsulated in connective tissue. The gland is composed of many secretory follicles. The follicles are lined with a single layer of cuboidal epithelium and are filled with a clear viscous glycoprotein called colloid. Extrafollicular cells (C cells) are found just outside the follicles.

20. Match the hormones from the thyroid gland with their descriptions.

A. most potent at controlling metabolism, B. regulates blood calcium, C. has four iodine atoms

1. thyroxine -4 iodine atoms

2. triiodothyronine - most potent at controlling metabolism

3. calcitonin - regulates blood calcium

\ 21. Define iodide pump.

This pump concentrates the iodides into the follicular cells where they combine with tyrosine in the synthesis of thyroid hormones.

\ \ 22. Diagram the control of thyroid hormone secretion.

Thyroid hormones are regulated by several factors. The most direct control is from thyroid stimulating hormone (TSH) from the anterior pituitary. TSH can also stimulate growth of the thyroid gland. Another factor is the hypothalamus. It secretes thyrotropin releasing hormone (TRH), which stimulates TSH release. External factors regulating thyroid hormone include extreme cold and emotional stress.

13.6 Parathyroid Glands

23. Describe the location and structure of the parathyroid glands.

The four parathyroid glands are located on the posterior surface of the thyroid gland, two on each side, arranged in a superior-inferior fashion. The parathyroid gland is a small yellowish-brown structure composed of many tightly packed secretory cells encapsulated in a connective tissue layer.

\ 24. Explain the general function of parathyroid hormone.

Parathyroid hormone (PTH) is also called parathormone. It is a protein that increases blood calcium ion levels and decreases blood phosphate ion levels by acting on the bones, kidneys, and intestines.

\ 25. Diagram the regulation of parathyroid hormone secretion.

Parathyroid hormone (PTH) is controlled by a negative feedback system between the parathyroid glands and the concentration of blood calcium ions. If blood calcium ion concentration is high, PTH secretion is inhibited.If blood calcium ion concentration is low, PTH secretion is increased. This causes bone resorption by osteocytes and osteoclasts which releases both calcium and phosphate ions into the bloodstream. Simultaneously, PTH causes the kidneys to keep calcium ions and excrete phosphate ions. Indirectly, PTH causes increased absorption of calcium ions from food in the intestines by influencing vitamin D metabolism.

13.7 Adrenal Glands

26. Distinguish between the adrenal medulla and the adrenal cortex.

The adrenal medulla is the central portion of an adrenal gland and consists of irregularly shaped cells grouped around blood vessels. The adrenal cortex is the outermost part of the adrenal gland and makes up the bulk of the gland. It is made of closely packed masses of epithelial layers that form three distinct zones: the zona glomerulosa, zona fasiculata, and zona reticularis—the outer, middle, and inner layers, respectively.

27. Match the adrenal hormones with their source and actions: A. cortex; sodium retention, B. cortex; male sex hormones, C. medulla;fight-flight-fight response, D. cortes; gluconeogenesis

1. cortisol D. cortex; gluconeogenesis

2. aldosterone A. cortex; sodium retention

3. epinephrine C. medulla; fight-flight-fight response

4. androgens B. cortex; male sex hormones

\ 28. Diagram control of aldosterone secretion.

\ When the adrenal cortex responds directly to changes in the concentration of potassium ions in blood plasma, it only slightly responds to a decrease in plasma sodium ions. Aldosterone secretion is indirectly regulated by juxtaglomerular cells in the kidneys that respond to changes in blood pressure and plasma sodium concentration. If either of these decreases, the juxtaglomerular cells release the enzyme renin. This enzyme decomposes the blood protein angiotensinogen, thus causing the release of the peptide angiotensin I. In the lungs, angiotensin I is converted into angiotensin II by the enzyme angiotensin-converting enzyme (ACE).When angiotensin II is carried to the adrenal cortex by the blood stream, it stimulates secretion of aldosterone.ACTH stimulates aldosterone secretion in response to other stimuli.

29. Diagram control of cortisol secretion.

is regulated by a negative feedback system. In response to increased glucose levels, the hypothalamus secretes CRH. This stimulates the anterior pituitary gland to secrete ACTH. The ACTH stimulates the adrenal cortex to secrete cortisol. As cortisol concentration increases, ACTH and CRH secretion decreases.

13.8 Pancreas

30. Describe the location and structure of the pancreas.

The pancreas is an elongated, flattened organ posterior to the stomach and the parietal peritoneum, and is attached to the duodenum by a duct. Structurally, the pancreas is composed of grouped cells called islets of Langerhans that are closely associated with blood vessels. The islets of Langerhans contain three types of cells: alpha, beta, and delta cells.

31. List the hormones the pancreatic islets secrete and their general functions.

Glucagon-is a protein secreted by alpha cells and is responsible for converting glycogen into glucose (glycogenolysis) in the liver, and noncarbohydrates into glucose (gluconeogenesis). Glucagon also stimulates the breakdown of fats into fatty acids and glycerol.

Insulin—Insulin is a protein secreted by beta cells that has the opposite effect of glucagon. In the liver, it stimulates formation of glycogen and inhibits conversion of noncarbohydrates. Insulin also promotes facilitated diffusion of glucose through the membranes of insulin target cells.

Somatostatin- is secreted by delta cells and inhibits glucagon and insulin secretion and helps regulate carbohydrates.

32. Diagram the control of pancreatic hormone secretion.

Glucagon and insulin are controlled by negative feedback systems sensitive to blood protein concentration.Glucagon release is stimulated when a low concentration of blood sugar is detected and inhibited as blood sugar concentration rises. Insulin release is stimulated when blood glucose concentration becomes too high. As blood glucose level concentration falls, insulin release is inhibited. Insulin and glucagon function together at various levels to keep blood glucose concentration relatively constant.

13.9 Other Endocrine Glands

33. Describe the location and general function of the pineal gland.

The pineal gland is small and oval, found deep between the cerebral hemispheres, and attached to the upper portion of the thalamus near the roof of the third ventricle. It is made up of pineal and neuroglial cells. The pineal gland secretes melatonin in response to periods of decreased light. It is believed that this aids in the regulation of circadian rhythms and inhibiting gonadotropins from the anterior pituitary gland. It may also help to regulate menstrual cycles.

34. Describe the location and general function of the thymus.

The thymus gland begins in childhood as a large substernal gland found in the mediastinum between the lungs, but diminishes in size with age. It plays an important role in immunity by secreting a group of hormones called thymosins that affect production of T lymphocytes (white blood cells).

\ 35. Name five additional hormone-secreting organs.

1.Ovaries

2.Placenta

3.Testes

4.Small intestine

5.Heart

6.Kidneys

7.Stomach lining

\ 13.10 Stress and Its Effects

36. Distinguish between a stressor and stress.

Stress is a condition in which potentially life-threatening changes occur in the body's internal environment. To maintain homeostasis, the body must react to counter these changes. A stressor is any factor that can cause these conditions

\ 37. List several factors that cause physical and/or psychological stress.

Extreme temperatures, decreased oxygen, infection, injuries, heavy exercise, and loud noise can cause physical stress. psychological stress: personal loss, thoughts of real or imagined dangers, unpleasant or lack of social interaction, anger, fear, grief, anxiety, depression, or guilt.

\ 38. Describe hormonal and nervous responses to stress.

Nerve impulses are transmitted to the hypothalamus. Blood glucose concentration increases, blood glycerol increases, blood fatty acids increase, heart rate increases, and blood pressure increases. Blood is shunted into skeletal muscles. Epinephrine intensifies. Increased ACTH increases the level of cortisol, etc. ADH promotes the retention of water, which increases blood volume. Renin increases. Aldosterone stimulates sodium retention by the kidneys.

13.11 Life-Span Changes

39. Levels of which hormones decrease with age? Which increase?

Growth hormone increases

Antidiuretic hormone increases

Calcitonin decreases

Thymosin decreases

Insulin increases

Parathyroid increases in women over 40