Chapter 18 Flashcards
1
Q
Hormone
A
A molecule that is released in one part of the body but regulates the activity of cells in other parts of the body. Most hormones enter interstitial fluid and then the bloodstream. The circulating blood delivers hormones to cells throughout the body.
2
Q
Exocrine glands
A
Secrete their products into ducts that carry the secretions into body cavities, into the lumen of an organ, or to the outer surface of the body. Include sudoriferous (sweat), sebaceous (oil), mucous, and digestive glands.
3
Q
Endocrine glands
A
Secrete hormones, which circulating blood delivers to target tissues. Include the pituitary, thyroid, parathyroid, adrenal, and pineal glands.
4
Q
Endocrine system
A
All endocrine glands and hormone-secreting cells. Include the hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue, and placenta.
5
Q
Receptors
A
A specific protein that hormones, like neurotransmitters, chemically bind to to influence their target cells.
6
Q
Down-regulation
A
A decrease in the number of target cell receptors when a hormone is present in excess. Makes a target cell less sensitive to a hormone.
7
Q
Up-regulation
A
An increase in the number of target receptors when a hormone is deficient. Makes a target cell more sensitive to a hormone.
8
Q
Circulating hormones
A
Hormones that pass from the secretory cells that make them into interstitial fluid and then into the blood. Most endocrine hormones are this.
9
Q
Local hormones
A
Act locally on neighboring cells or on the same cell that secreted them without entering the bloodstream.
10
Q
What are the two types of local hormones? Describe them
A
- Paracrines: local hormones that act on neighboring cells.
- Autocrines: local hormones that act on the same cell that secreted them.
11
Q
What are the three types of lipid-soluble hormones?
A
- Steroid hormones
- Thyroid hormones (T3 and T4)
- Nitric oxide (NO)
12
Q
What are the three types of water-soluble hormones?
A
- Amine hormones
- Peptide hormones and protein hormones
- Eicosanoid hormones (prostaglandins (PGs) and leukotrienes (LTs))
13
Q
What are the three functions of transport proteins?
A
- They make lipid-soluble hormones temporarily water-soluble, thus increasing their solubility in blood.
- They retard passage of small hormone molecules through the filtering mechanism in the kidneys, thus slowing the rate of hormone loss in the urine.
- They provide a ready reserve of hormone, already present in the bloodstream.
14
Q
Free fraction
A
Molecules of a lipid-soluble hormone that are not bound to a transport protein. Diffuses out of capillaries, binds to receptors, and triggers responses.
15
Q
What is the action of lipid-soluble hormones?
A
Bind to receptors inside target cells.
16
Q
What is the action of water-soluble hormones?
A
Cannot diffuse through the lipid bilayer of the plasma membrane and bind to receptors inside the target cells, like lipid-soluble hormones. Instead, they bind to receptors embedded in the plasma membranes of target cells.
17
Q
First messenger
A
The hormone. Causes production of a second messenger.
18
Q
Second messenger
A
Is located inside the cell, where specific hormone-stimulated responses take place (Eg. Cyclic adenosine monophosphate AKA cyclic AMP (cAMP)).
19
Q
Permissive effect
A
When the action of one hormone on its target cell requires simultaneous or recent exposure to a second hormone. Sometimes the permissive hormone increases the number of receptors for the other hormone, and sometimes it promotes the synthesis of an enzyme required for the expression of the other hormone’s effects.
20
Q
Synergistic effect
A
When the effect of two hormones acting together is greater than the sum of their individual effects.
21
Q
Antagonistic effects
A
When one hormone opposes the actions of another hormone.
22
Q
What three things is hormone secretion regulated by?
A
- Signals from the nervous system
- Chemical changes in the blood
- Other hormones
23
Q
Pituitary gland
A
AKA hypophysis; the “master” endocrine gland; secretes several hormones that control other endocrine glands. Contains cells that secrete 7 different hormones that play important roles in the regulation of virtually all aspects of growth, development, metabolism, and homeostasis.
24
Q
What two parts can the pituitary gland be divided into?
A
- Anterior pituitary
- Posterior pituitary
25
Anterior pituitary
AKA adenohypophysis; accounts for about 75% of the total weight of the gland and is composed of epithelial tissue.
26
What two parts can the anterior pituitary be divided into? Describe them
1. Pars distalis: larger portion.
2. Pars tuberalis: forms a sheath around the infundibulum.
27
Posterior pituitary
AKA neurohypophysis; accounts for about 25% of the total weight of the gland and is composed of neural tissue.
28
What three parts can the posterior pituitary be divided into? Describe them
1. Pars nervosa: the larger bulbar portion
2. Infundibulum
3. Pars intermedia: atrophies (shrinks) during human fetal development and ceases to exist as a separate lobe in adults.
29
Hypothalamus
The “master” of the pituitary gland; is the major link between the nervous and endocrine systems. Contains cells that secrete 9 different hormones that play important roles in the regulation of virtually all aspects of growth, development, metabolism, and homeostasis.
30
Infundibulum
Stalk that attaches the pituitary gland to the hypothalamus.
31
What are the five types of anterior pituitary cells?
1. Somatotrophs
2. Thyrotrophs
3. Gonadotrophs
4. Lactotrophs
5. Corticotrophs
32
What hormone(s) do somatotrophs secrete? Describe them
Secrete growth hormone (GH), also known as human growth hormone (hGH) or somatotropin. GH stimulates general body growth and regulates aspects of metabolism.
33
What hormone(s) do thyrotrophs secrete? Describe them
Secrete thyroid-stimulating hormone (TSH), also known as thyrotropin. TSH controls the secretions and other activities of the thyroid gland.
34
What hormone(s) do gonadotrophs secrete? Describe them
Secrete two gonadotropins: follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH both act on the gonads (testes and ovaries). In men, they stimulate the testes to produce sperm and to secrete testosterone. In women, they stimulate the ovaries to mature oocytes (eggs) and to secrete estrogens and progesterone.
35
What hormone(s) do lactotrophs secrete? Describe them
Secrete prolactin (PRL), which initiates milk production in the mammary glands.
36
What hormone(s) do corticotrophs secrete? Describe them
Secrete adrenocorticotropic hormone (ACTH), also known as corticotropin, which stimulates the adrenal cortex to secrete glucocorticoids such as cortisol. Some corticotrophs, remnants of the pars intermedia, also secrete melanocyte-stimulating hormone (MSH).
37
What five releasing hormones does the hypothalamus secrete?
1. Growth hormone-releasing hormone (GHRH) (AKA somatocrinin)
2. Thyrotropin-releasing hormone (TRH)
3. Corticotropin-releasing hormone (CRH)
4. Prolactin-releasing hormone (PRH)
5. Gonadotropin-releasing hormone (GnRH)
38
What does growth hormone-releasing hormone (GHRH) stimulate the secretion of?
Stimulates secretion of growth hormone.
39
What does thyrotropin-releasing hormone (TRH) stimulate the secretion of?
Stimulates secretion of thyroid-stimulating hormone.
40
What does corticotropin-releasing hormone (CRH) stimulate the secretion of?
Stimulates secretion of adrenocorticotropic hormone.
41
What does prolactin-releasing hormone (PRH) stimulate the secretion of?
Stimulates secretion of prolactin.
42
What does gonadotropin-releasing hormone (GnRH) stimulate the secretion of?
Stimulates secretion of FSH and LH.
43
What two inhibiting hormones does the hypothalamus secrete?
1. Growth hormone-inhibiting hormone (GHIH) (AKA somatostatin)
2. Prolactin-inhibiting hormone (PIH) (AKA dopamine)
44
What does growth hormone-inhibiting hormone (GHIH) suppress the secretion of?
Suppresses secretion of growth hormone.
45
What does prolactin-inhibiting hormone (PIH) suppress the secretion of?
Suppresses secretion of prolactin.
46
In the hypophyseal portal system, blood flows from capillaries in the hypothalamus into portal veins that carry blood to capillaries of the anterior pituitary. In other words, the hormones carried by the system allow communication between the hypothalamus and anterior pituitary and establish an important link between the nervous system and the endocrine system. The ______, branches of the internal carotid arteries, bring blood into the hypothalamus. At the junction of the median eminence of the hypothalamus and the infundibulum, these arteries divide into a capillary network called the ______. From the primary plexus, blood drains into the ______ that pass down the outside of the infundibulum. In the anterior pituitary, the hypophyseal portal veins divide again and form another capillary network called the ______. ______ drain blood from the anterior pituitary.
Superior hypophyseal arteries; primary plexus of the hypophyseal portal system; hypophyseal portal veins; secondary plexus of the hypophyseal portal system; Hypophyseal veins
47
Neurosecretory cells
Clusters of neurons that synthesize the hypothalamic releasing and inhibiting hormones in their cell bodies and package the hormones inside vesicles, which reach the axon terminals by fast axonal transport, where they are stored.
48
Tropic hormones
AKA tropins; the anterior pituitary hormones that act on other endocrine glands.
49
Growth hormone (GH)
AKA somatotropin; stimulates liver, muscle, cartilage, bone, and other tissues to synthesize and secrete insulin-like growth factors (IGFs), which in turn promote growth of body tissues. GH acts directly on target cells to enhance lipolysis and decrease glucose uptake.
50
Insulin-like growth factors (IGFs)
AKA somatomedins; small protein hormones that growth hormone (GH) indirectly secretes its growth-promoting effects through.
51
What are the three specific functions of IGFs?
1. Increase growth of bones and soft tissues
2. Enhance lipolysis
3. Decrease glucose uptake
52
How is GH secretion regulated?
Secretion of GH is stimulated by growth hormone-releasing hormone (GHRH) and inhibited by growth hormone-inhibiting hormone (GHIH).
53
Thyroid-stimulating hormone (TSH)
AKA thyrotropin; stimulates synthesis and secretion of thyroid hormones by thyroid gland.
54
Follicle-stimulating hormone (FSH)
In females, initiates development of oocytes and induces ovarian secretion of estrogens. In males, stimulates testes to produce sperm.
55
Luteinizing hormone (LH)
In females, stimulates secretion of estrogens and progesterone, ovulation, and formation of corpus luteum. In males, stimulates testes to produce testosterone.
56
Prolactin (PRL)
Together with other hormones, promotes milk production by mammary glands.
57
Lactation
Consist of milk production and ejection.
58
Adrenocorticotropic hormone (ACTH)
AKA corticotropin; stimulates secretion of glucocorticoids (mainly cortisol) by adrenal cortex.
59
Melanocyte-stimulating hormone (MSH)
Exact role in humans is unknown but may influence brain activity; when present in excess, can cause darkening of skin.
60
The posterior pituitary ______ synthesize hormones, and it stores and releases two hormones. It consists of axons and axon terminals of more than 10,000 hypothalamic neurosecretory cells. The cell bodies of the neurosecretory cells are in the ______; their axons form the ______. This tract begins in the hypothalamus and ends near blood capillaries in the posterior pituitary. The neuronal cell bodies of both the paraventricular and the supraoptic nuclei synthesize the hormones ______ and ______, also called vasopressin. The axon terminals in the posterior pituitary are associated with specialized neuroglia called ______. These cells have a supporting role similar to that of astrocytes.
Doesn't; paraventricular and supraoptic nuclei of the hypothalamus; hypothalamic-hypophyseal tract; oxytocin (OT); antidiuretic hormone (ADH); pituicytes
61
Blood is supplied to the posterior pituitary by the ______, which branch from the internal carotid arteries. In the posterior pituitary, the inferior hypophyseal arteries drain into the ______, a capillary network that receives secreted oxytocin and antidiuretic hormone. From this plexus, hormones pass into the ______ for distribution to target cells in other tissues.
Inferior hypophyseal arteries; capillary plexus of the infundibular process; hypophyseal veins
62
What controls oxytocin (OT) secretion?
Neurosecretory cells of hypothalamus secrete OT in response to uterine distension and stimulation of nipples.
63
What controls antidiuretic hormone (ADH) secreation?
Neurosecretory cells of hypothalamus secrete ADH in response to elevated blood osmotic pressure, dehydration, loss of blood volume, pain, or stress; inhibitors of ADH secretion include low blood osmotic pressure, high blood volume, and alcohol.
64
What is the action of oxytocin (OT)?
Stimulates contraction of smooth muscle cells of uterus during childbirth; stimulates contraction of myoepithelial cells in mammary glands to cause milk ejection.
65
What is the action of antidiuretic hormone (ADH)?
AKA vasopressin; conserves body water by decreasing urine volume; decreases water loss through perspiration; raises blood pressure by constricting arterioles.
66
Osmoreceptors
Neurons in the hypothalamus that monitor changes in blood osmolarity.
67
Thyroid gland
Butterfly-shaped; located just inferior to the larynx (voice box). Composed of right and left lateral lobes, one on either side of the trachea.
68
Isthmus
Connect right and left lateral lobes of the thyroid gland.
69
Thyroid follicles
Microscopic spherical sacs that make up most of the thyroid gland.
70
Follicular cells
Cells that make up the wall of each follicle by extending into the lumen (internal space) of the follicle. When the follicular cells are inactive, their shape is low cuboidal to squamous, but under the influence of TSH they become active in secretion and range from cuboidal to low columnar in shape. Produce the two thyroid hormones.
71
Parafollicular cells
AKA C cells; lie between follicles. Produce calcitonin (CT).
72
Basement membrane
Surrounds each follicle.
73
Colloid
Lumen of the thyroid follicle.
74
What are the 8 steps involved in the synthesis and secretion of thyroid hormones (T3 and T4)?
1. Iodide trapping
2. Synthesis of thyroglobulin (TGB)
3. Oxidation of iodide
4. Iodination of thyrosine
5. Coupling of T1 and T2
6. Pinocytosis and digestion of colloid
7. Secretion of thyroid hormones
8. Transport in the blood
75
What are the actions of thyroid hormones?
Increase basal metabolic rate; stimulate synthesis of proteins; increase use of glucose and fatty acids for ATP production; increase lipolysis; enhance cholesterol excretion; accelerate body growth; contribute to development of nervous system.
76
Basal metabolic rate (BMR)
The rate of energy expenditure (used) under standard or basal conditions (awake, at rest, and fasting). When MMR increases, cellular metabolism of carbohydrates, lipids, and proteins increases.
77
Calorigenic effect
A phenomenon in which cells produce and use more ATP, BMR increases, more heat is given off, and body temperature rises.
78
What controls thyroid hormone secretion?
Secretion is increased by thyrotropin-releasing hormone (TRH), which stimulates release of thyroid-stimulating hormone (TSH) in response to low thyroid hormone levels, low metabolic rate, cold, pregnancy, and high altitudes; TRH and TSH secretions are inhibited in response to high thyroid hormone levels; high iodine level suppresses T3/T4 secretion.
79
What are the actions of calcitonin (CT)?
Lowers blood levels of Ca2+ and HPO4 2− by inhibiting bone resorption by osteoclasts and by accelerating uptake of calcium and phosphates into bone extracellular matrix.
80
What controls CT secretion?
High blood Ca2+ levels stimulate secretion; low blood Ca2+ levels inhibit secretion.
81
Parathyroid glands
Normally four in number, are embedded in the posterior surface of the thyroid gland.
82
What are the two kinds of epithelial cells within the parathyroid gland? Describe them
1. Chief cells: more numerous cells; produce parathyroid hormone (PTH), AKA parathormone.
2. Oxyphil cell
83
What are the actions of parathyroid hormones?
Increases blood Ca2+ and Mg2+ levels and decreases blood HPO4 2− level; increases bone resorption by osteoclasts; increases Ca2+ reabsorption and HPO4 2− excretion by kidneys; promotes formation of calcitriol, which increases rate of dietary Ca2+ and Mg2+ absorption.
84
What controls parathyroid hormone secretion?
Low blood Ca2+ levels stimulate secretion; high blood Ca2+ levels inhibit secretion.
85
Adrenal glands
AKA suprarenal glands; pair of glands – one of which lies superior to each kidney in the retroperitoneal space. Have a flattened pyramidal shape.
86
During embryonic development, the adrenal glands differentiate into two distinct regions. What are they?
1. Adrenal cortex
2. Adrenal medulla
87
Adrenal cortex
Large peripheral region that comprises 80-90% of the gland. Secretes steroid hormones that are essential for life.
88
What three zones does the adrenal cortex get subdivided into?
1. Zona glomerulosa
2. Zona fasciculata
3. Zona reticularis
89
Zona glomerulosa
Outer zone. Its cells, which are closely packed and arranged in spherical clusters and arched columns, secrete mineralocorticoids.
90
What are the actions of mineralocorticoids (mainly aldoesterone)?
Hormones that affect mineral homeostasis. Increase blood levels of Na+ and water; decrease blood level of K+.
91
Zona fasciculata
Middle zone. Is the widest of the three zones and consists of cells arranged in long, straight columns. The cells of the zona fasciculata secrete mainly glucocorticoids.
92
What are the actions of glucocorticoids (mainly cortisol AKA hydrocortisone; also includes corticosterone and cortisone)?
Affects glucose homeostasis. Increase protein breakdown (except in liver), stimulate gluconeogenesis and lipolysis, provide resistance to stress, dampen inflammation, depress immune responses.
93
Zona reticularis
Inner zone. Are arranged in branching cords. They synthesize small amounts of weak androgens.
94
What are the actions of androgens (mainly dehydropiandrosterone (DHEA))?
Steroid hormones that have masculinizing effects. Assist in early growth of axillary and pubic hair in both sexes; in females, contribute to libido and are source of estrogens after menopause.
95
What controls mineralocorticoids (mainly aldoesterone) secretion?
The renin-angiotensin-aldosterone (RAA) pathway controls secretion of aldosterone. Increased blood K+ level and angiotensin II stimulate secretion.
96
Gluconeogenesis
Conversion of a substance other than glycogen or another monosaccharide into glucose.
97
What controls glucocorticoid (mainly cortisol) secretion?
ACTH stimulates release; corticotropin-releasing hormone (CRH) promotes ACTH secretion in response to stress and low blood levels of glucocorticoids.
98
Corticotropin-releasing hormone (CRH)
Promotes the release of ACTH from the anterior pituitary.
99
What controls androgen (mainly dehydroepiandrosterone (DHEA)) secretion?
ACTH stimulates secretion.
100
Adrenal medulla
Small central region that comprises 10-20% of the gland. Secretes epinephrine and norepinephrine (NE), also called adrenaline and noradrenaline, respectively. Enhance effects of sympathetic division of autonomic nervous system (ANS) during stress.
101
Chromaffin cells
Hormone-producing cells of the adrenal medulla. Are innervated by sympathetic preganglionic neurons of the ANS. Hormone release can occur very quickly. Secrete an unequal amount of hormones – about 80% epinephrine and 20% norepinephrine (NE).
102
What controls epinephrine and NE secretion?
Sympathetic preganglionic neurons release acetylcholine, which stimulates secretion.
103
Pancreas
Is both an endocrine gland and an exocrine gland. Is a flattened organ that measures about 12.5–15 cm (5-6 in.) in length, and is located in the curve of the duodenum, the first part of the small intestine, and consists of a head, a body, and a tail.
104
Acini
Clusters in which roughly 99% of the exocrine cells of the pancreas are arranged into. Produce digestive enzymes, which flow into the gastrointestinal tract through a network of ducts.
105
Pancreatic islets
AKA islets of Langerhans; 1-2 million tiny clusters of endocrine tissue that are scattered among the exocrine acini.
106
What are the four types of cells in the pancreatic islet?
1. Alpha AKA A cells
2. Beta AKA B cells
3. Delta AKA D cells
4. F cells
107
Alpha AKA A cells
Constitute about 17% of pancreatic islet cells and secrete glucagon.
108
What controls glucagon secretion?
Negative feedback. Decreased blood level of glucose, exercise, and mainly protein meals stimulate secretion; somatostatin and insulin inhibit secretion.
109
What are the actions of glucagon?
Raises blood glucose level by accelerating breakdown of glycogen into glucose in liver (glycogenolysis), converting other nutrients into glucose in liver (gluconeogenesis), and releasing glucose into blood.
110
Beta AKA B cells
Constitute about 70% of pancreatic islet cells and secrete insulin.
111
What controls insulin secretion?
Negative feedback. Increased blood level of glucose, acetylcholine (released by parasympathetic vagus nerve fibers), arginine and leucine (two amino acids), glucagon, GIP, GH, and ACTH stimulate secretion; somatostatin inhibits secretion.
112
What are the actions of insulin?
Lowers blood glucose level by accelerating transport of glucose into cells, converting glucose into glycogen (glycogenesis), and decreasing glycogenolysis and gluconeogenesis; increases lipogenesis and stimulates protein synthesis.
113
Delta AKA D cells
Constitute about 7% of pancreatic islet cells and secrete somatostatin.
114
What controls somatostatin secretion?
Pancreatic polypeptide inhibits secretion.
115
What are the actions of somatostatin?
Inhibits secretion of insulin and glucagon; slows absorption of nutrients from gastrointestinal tract.
116
F cells
Constitute the remainder of pancreatic islet cells and secrete pancreatic polypeptide.
117
What controls pancreatic polypeptide secretion?
Meals containing protein, fasting, exercise, and acute hypoglycemia stimulate secretion; somatostatin and elevated blood glucose level inhibit secretion.
118
What are the actions of pancreatic polypeptide?
Inhibits somatostatin secretion, gallbladder contraction, and secretion of pancreatic digestive enzymes.
119
Gonads
The organs that produce gametes – sperm in males and oocytes in females. In addition to their reproductive function, the gonads secrete hormones.
120
Ovaries
Paired oval bodies located in the female pelvic cavity. Produce several steroid hormones, including two estrogens, progesterone, inhibin, and during pregnancy, relaxin (RLX).
121
What are the actions of estrogens and progesterone?
Together with gonadotropic hormones of anterior pituitary, regulate female reproductive cycle, maintain pregnancy, prepare mammary glands for lactation, and promote development and maintenance of female secondary sex characteristics.
122
What are the actions of relaxin (RLX)?
Increases flexibility of pubic symphysis during pregnancy; helps dilate uterine cervix during labor and delivery.
123
What are the actions of inhibin?
Inhibits secretion of follicle-stimulating hormone (FSH) from anterior pituitary.
124
Testes
Oval glands that lie in the scrotum. The main hormone produced and secreted by the testes is testosterone, an androgen or male sex hormone. The testes also produce inhibin.
125
What are the actions of testosterone?
Stimulates descent of testes before birth; regulates sperm production; promotes development and maintenance of male secondary sex characteristics.
126
Pineal gland
A small endocrine gland attached to the roof of the third ventricle of the brain at the midline. It consists of masses of neuroglia and secretory cells called pinealocytes. Secretes melatonin.
127
Melatonin
An amine hormone derived from serotonin. Appears to contribute to the setting of the body’s biological clock, which is controlled by the suprachiasmatic nucleus of the hypothalamus. Also thought to promote sleepiness. Additionally, melatonin is a potent antioxidant that may provide some protection against damaging oxygen free radicals.
128
Thymus
Is located behind the sternum between the lungs. Plays a role in immunity.
129
What are the four hormones produced by thymus?
1. Thymosin
2. Thymic humoral factor (THF)
3. Thymic factor (TF)
4. Thymopoietin
All promote the maturation of T cells (a type of white blood cell that destroys microbes and foreign substances) and may retard the aging process.
130
What are the actions of cholecalciferol (in the skin)?
Plays a role in the synthesis of calcitriol, the active form of vitamin D.
131
What are the actions of gastrin (in the gastrointestinal tract)?
Promotes secretion of gastric juice; increases movements of the stomach.
132
What are the actions of glucose-dependent insulinotropic peptide (GIP) (in the gastrointestinal tract)?
Stimulates release of insulin by pancreatic beta cells.
133
What are the actions of secretin (in the gastrointestinal tract)?
Stimulates secretion of pancreatic juice and bile.
134
What are the actions of cholecystokinin (CCK) (in the gastrointestinal tract)?
Stimulates secretion of pancreatic juice; regulates release of bile from gallbladder; causes feeling of fullness after eating.
135
What are the actions of human chorionic gonadotropin (hCG) (in the placenta)?
Stimulates corpus luteum in ovary to continue production of estrogens and progesterone to maintain pregnancy.
136
What are the actions of estrogen and progesterone (in the placenta)?
Maintain pregnancy; help prepare mammary glands to secrete milk.
137
What are the actions of human chorionic somatomammotropin (hCS) (in the placenta)?
Stimulates development of mammary glands for lactation.
138
What are the actions of renin (in the kidneys)?
Part of reaction sequence that raises blood pressure by bringing about vasoconstriction and secretion of aldosterone.
139
What are the actions of erythropoietin (EPO) (in the kidneys)?
Increases rate of red blood cell formation.
140
What are the actions of calcitriol (in the kidneys)?
Aids in absorption of dietary calcium and phosphorus.
141
What are the actions of atrial natriuretic peptide (ANP) (in the heart)?
Decreases blood pressure.
142
What are the actions of leptin (in adipose tissue)?
Suppresses appetite; may increase FSH and LH activity.
143
What are the two eicosanoids?
1. Prostaglandins
2. Leukotrienes (LTs)
144
Prostaglandins (PGs)
Alter smooth muscle contraction, glandular secretions, blood flow, reproductive processes, platelet function, respiration, nerve impulse transmission, lipid metabolism, and immune responses. They also have roles in promoting inflammation and fever, and in intensifying pain.
145
Leukotrienes (LTs)
Stimulate chemotaxis (attraction to a chemical stimulus) of white blood cells and mediate inflammation.
146
Thromboxane (TX)
A modified PG that constricts blood vessels and promotes platelet activation.
147
Growth factors
Play important roles in tissue development, growth, and repair. Are mitogenic substances – they cause growth by stimulating cell division. Many growth factors act locally, as autocrines or paracrines.
148
Eustress
Stress that prepares us to meet certain challenges and thus is helpful.
149
Distress
Stress that is harmful.
150
Stressor
Any stimulus that produces a stress response. May be almost any disturbance of the human body – heat or cold, environmental poisons, toxins given off by bacteria, heavy bleeding from a wound or surgery, or a strong emotional reaction.
151
Stress response AKA general adaptation syndrome (GAS)
A sequence of bodily changes elicited by a variety of stressful conditions or noxious agents. Are controlled mainly by the hypothalamus.
152
What are the three stages of the stress response?
1. Fight-or-flight response
2. Resistance reaction
3. Exhaustion
153
How is stress connected to disease?
Stress can lead to particular diseases by temporarily inhibiting certain components of the immune system.
