Chapter 9. The Endocrine System. Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical College

Transcription

1 Chapter 9 The Endocrine System Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical College

2 Introduction Hormone and Target Cells Steroids and Non-Steroids HW: Read / Take notes from text p Complete WB 184

3 Endocrine System

4 Endocrine vs Nervous Cell Communication

5 Nervous vs. Endocrine System

6 Nervous vs. Endocrine System Communication: Electrical impulses Neurotransmitters Hormones Reaction time 1-10 msec Stops immediately Seconds days Response lingers Effects Specific organs Often entire body

7 Endocrine System Anatomy Endocrine glands secrete into blood, lymph Exocrine glands secrete into ducts

8 Major Endocrine Organs Many glands are purely endocrine Anterior pituitary, thyroid, adrenals, parathyroids Some glands are mixed glands endocrine and exocrine functions pancreas, ovaries, testes

9 Endocrine System Functions Regulate metabolic processes Controls rate of chemical reactions Helps transport across membranes Helps regulate water & electrolytes Regulates glucose and calcium concentrations Reproduction, development, growth Mobilization of body defenses

10 Endocrine Hormones Produced by specialized cells (endocrine glands) Blood transfers hormones to target sites Hormones regulate activity of other cells Turns genes on / off

11 The Chemistry of Hormones (2 types) Hormones are classified chemically as Amino acid based (non-steroids): Proteins Peptides Amines Steroids made from cholesterol

12 Hormone Action Hormones alter cellular activity. Typically, one or more occurs: 1. Membrane permeability or electrical state changes 2. Synthesis of proteins (often enzymes) 3. Enzyme activation or inactivation 4. Stimulation of mitosis (cell division) 5. Promotes cell to secrete substance

13 Hormone Action Hormones affect only certain tissues / organs (target cells / target organs) Hormone binding to receptor alters cellular activity Target cells must have specific protein receptors On cell membrane OR Inside the cell

14 Non-Steroid Cell Communication

15 Second-Messenger System (Nonsteroid Hormone Action) 1. Hormone (1 st messenger) binds to membrane receptor 2. Activated receptor sets off a series of reactions Activates an enzyme 3. Enzyme catalyzes a reaction Activates second-messenger molecule (cyclic AMP, Ca 2+ ) 4. Additional intracellular changes promote cellular response

16 Figure 9.1b Mechanisms of hormone action. Slide 5 Nonsteroid hormone (first messenger) Enzyme Cytoplasm ATP camp Second messenger Receptor protein Plasma membrane of target cell 4 Effect on cellular function 2015 Pearson Education, Inc. Nonsteroid hormone action

17 Steroid Cell Communication

18 Direct Gene Activation (Steroid Hormone Action) 1. Steroid hormones diffuse through plasma membrane 2. Steroid hormones bind to a receptor protein In the cytoplasm OR In the nucleus 3. Steroid hormones enter the nucleus 4. Hormone-receptor complex binds DNA 5. Activates genes 6. New proteins are made

19 Figure 9.1a Mechanisms of hormone action. Slide 1 Steroid hormone Cytoplasm 1 2 Nucleus Receptor protein 3 Hormone-receptor complex 4 DNA New protein mrna 5 Plasma membrane of target cell Pearson Education, Inc. (a) Steroid hormone action

20 3 Ways to Stimulate Endocrine Glands Neural Hormonal Humoral Feedback Mechanisms Negative Positive HW: Read / take notes from text p Complete Feedback Mechanisms packet

21 Endocrine Gland Stimuli Three categories of stimuli that activate endocrine glands 1. Hormonal 2. Neural 3. Humoral

22 Hormonal Stimuli of Endocrine Glands Most common stimulus Endocrine organs are activated by other hormones

23 Hormonal gland secretion

24 Hormonal stimulus 1 The hypothalamus secretes hormones that Hypothalamus 2 stimulate the anterior pituitary gland to secrete hormones that Anterior pituitary gland Thyroid gland Adrenal cortex Gonad (testis) 3 stimulate other endocrine glands to secrete hormones 2015 Pearson Education, Inc.

25 Neural Stimuli of Endocrine Glands Nerve impulses stimulate hormone release Under sympathetic nervous system control (mostly)

26 Figure 9.2c Endocrine gland stimuli. Neural stimulus 1 Sympathetic fiber stimulates adrenal medulla cells CNS (spinal cord) Sympathetic fibers Pearson Education, Inc.

27 Figure 9.2c Endocrine gland stimuli. Neural stimulus 1 Adrenal medulla 2015 Pearson Education, Inc. 2 cells secrete epinephrine and norepinephrine

28 Neural Stimuli Results in Release of Epinephrine Increase cardiac output Dilate coronary blood vessels Increase muscle contraction Increase mental alertness Increase glycogen Increase blood sugar

29 Humoral Stimuli of Endocrine Glands Blood levels of certain ions and nutrients stimulate hormone release

30 Regulation of Calcium Ion Concentration in Blood Humoral stimulus 1 Capillary blood contains low concentration of Ca 2+, which stimulates Capillary (low Ca 2+ in blood) Thyroid gland (posterior view) Parathyroid glands PTH Parathyroid glands 2 secretion of parathyroid hormone (PTH) by parathyroid glands)

31 Control of Hormone Release: Negative Feedback Mechanism (usually) Hormone levels maintained by negative feedback What triggers the release of more hormone? A stimulus Low hormone levels in the blood What stops the release of hormones? Hormone reaches appropriate level in the blood

32 Negative Feedback Mechanism

33 Negative Feedback Mechanism

34 Master Controls of the Endocrine System Hypothalamus Pituitary Gland Posterior Pituitary Gland (2 hormones) HW: Read / Take notes from text p

35 Pituitary Gland and Hypothalamus

36 Pituitary Gland and Hypothalamus Pituitary gland is the size of a pea Hangs by a stalk from the hypothalamus Protected by the sphenoid bone Has two functional lobes Anterior pituitary glandular tissue Posterior pituitary nervous tissue Called the master endocrine gland

37 Pituitary Gland and Hypothalamus Hypothalamus makes two hormones: antidiuretic hormone (ADH) oxytocin Neurosecretory cells bring hormones to posterior pituitary Posterior pituitary is a storage site

38 Posterior Pituitary Stores Hormones When stimulated Releases ADH Releases Oxytocin Arterial blood supply Venous drainage ADH Oxytocin

39 Posterior Pituitary - ADH Antidiuretic hormone (ADH) Prevents dehydration Inhibits urine production (diuresis) Promotes water reabsorption by the kidneys Alcohol inhibits ADH secretion Therefore increases water loss Large amounts of ADH vasoconstriction of arterioles increases blood pressure ADH is also known as vasopressin ADH hyposecretion results in Diabetes insipidus

40 Posterior Pituitary - Oxytocin Oxytocin Stimulates contractions of the uterus during labor sexual relations breastfeeding Causes milk ejection (let-down reflex) in a breastfeeding woman Increases sense of calmness Pitocin: synthetic oxytocin Used to induce labor Used post labor to stop bleeding

41 Posterior Pituitary When stimulated Releases ADH Prevents water loss Releases Oxytocin Uterine contractions Milk let-down Increases calmness Arterial blood supply Venous drainage ADH Kidney Oxytocin Mammary glands Uterine muscles

42 Pituitary Gland and Hypothalamus Hypothalamus produces releasing / inhibiting hormones These hormones are released into portal circulation, which connects hypothalamus to anterior pituitary Hypothalamus also makes two hormones: oxytocin and antidiuretic hormone Carried to posterior pituitary via neurosecretory cells for storage

43 Master Controls of the Endocrine System Hypothalamus Pituitary Gland Anterior Pituitary Gland (6 hormones) HW: Read / Take notes from text p Complete WB

44 Pituitary Gland and Hypothalamus

45 Hormones of the Anterior Pituitary Six anterior pituitary hormones Hormonal control All amino acid-based hormones Regulated by negative feedback (mostly) Two affect non-endocrine targets: 1. Growth hormone Bones Muscles 2. Prolactin Breast milk production in females Unknown function in males

46 Growth Hormone General metabolic hormone Causes amino acids to be built into proteins Causes fats to be broken down for a source of energy Plays a role in determining final body size Growth of skeletal muscles Growth of long bones

47 Growth Hormone Disorders Pituitary dwarfism hyposecretion of GH during childhood Gigantism hypersecretion of GH during childhood Acromegaly hypersecretion of GH in adulthood continued growth of hand, feet, and facial bones

48 Prolactin (PRL) In females, stimulates and maintains milk production (after childbirth) Positive feedback Function in males is unknown

49 Figure 9.5 Hormones of the anterior pituitary and their major target organs. Hypothalamus Anterior pituitary Growth hormone (GH) Bones and muscles Prolactin (PRL) Mammary glands 2015 Pearson Education, Inc.

50 Hormones of the Anterior Pituitary Four are tropic hormones stimulate other endocrine glands to release hormones 1. Thyroid-stimulating hormone (TSH) 2. Adrenocorticotropic hormone (ACTH) 3. Follicle-stimulating hormone (FSH) 4. Luteinizing hormone (LH)

51 Hormones of the Anterior Pituitary Adrenocorticotropic hormone (ACTH) Regulates endocrine activity of the adrenal cortex Thyroid-stimulating hormone (TSH) Influences growth and activity of the thyroid gland

52 Figure 9.5 Hormones of the anterior pituitary and their major target organs. Hypothalamus Adrenocorticotropic hormone (ACTH) Thyroid stimulating hormone (TSH) Adrenal cortex Thyroid 2015 Pearson Education, Inc.

53 Hormones of the Anterior Pituitary Gonadotropic hormones Regulate hormonal activity of the gonads Follicle-stimulating hormone (FSH) Stimulates follicle development in ovaries Stimulates sperm development in testes Luteinizing hormone (LH) Triggers ovulation of an egg in females Stimulates testosterone production in males

54 Figure 9.5 Hormones of the anterior pituitary and their major target organs. Hypothalamus Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) Testes or ovaries 2015 Pearson Education, Inc.

55 Figure 9.5 Hormones of the anterior pituitary and their major target organs. Releasing hormones secreted into portal circulation Hypothalamus Growth hormone (GH) Anterior pituitary Hypophyseal portal system Posterior pituitary Adrenocorticotropic hormone (ACTH) Bones and muscles Prolactin (PRL) Mammary glands Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) Thyrotropic hormone (TH) Thyroid Adrenal cortex Testes or ovaries 2015 Pearson Education, Inc.

56 Control of Metabolism and Ca 2+ ion concentration Thyroid (3 hormones) Hormonal stimuli Humoral stimuli Parathyroid (1 hormone) Humoral stimuli HW: Read / Take notes from text p Copy Figure 9.10 into notes

57 Thyroid Gland Found at the base of the throat Consists of two lobes and a connecting isthmus Produces two hormones: 1. Thyroid hormone (T 3 and T 4 ) 2. Calcitonin

58 Figure 9.7a The thyroid gland. Thyroid cartilage Epiglottis Common carotid artery Isthmus of thyroid gland Trachea Brachiocephalic artery Left subclavian artery Left lobe of thyroid gland Aorta 2015 Pearson Education, Inc. (a) Gross anatomy of the thyroid gland, anterior view

59 Thyroid Hormone (1 functional hormone) Major metabolic hormone Controls rate of oxidation of glucose Chemical energy (ATP) Body heat Composed of two iodine-containing hormones Thyroxine (T 4 ) Triiodothyronine (T 3 ) converts to T 4 at target cells Needed for tissue growth and development

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61 Figure 9.7b The thyroid gland. Colloid-filled follicles Follicle cells Parafollicular cells 2015 Pearson Education, Inc. (b) Photomicrograph of thyroid gland follicles (380 )

62 Thyroid Gland Thyroid hormone disorders Goiters Thyroid gland enlarges because of lack of iodine Salt is iodized to prevent goiters Cretinism Caused by hyposecretion of thyroxine Results in dwarfism during childhood

63 Thyroid Gland Thyroid hormone disorders Myxedema Caused by hypothyroidism in adults Results in physical and mental sluggishness Graves disease Caused by hyperthyroidism Results in increased metabolism, heat intolerance, rapid heartbeat, weight loss, and exophthalmos

64 Thyroid Gland Calcitonin Decreases blood calcium levels Causes calcium deposition on bone Antagonistic to parathyroid hormone Disorder: Calcinosis calcification of soft tissue

65 Parathyroid Glands On the posterior of the thyroid Parathyroid hormone (PTH) Stimulates osteoclasts remove calcium from bone Hypercalcemic hormone ( blood calcium levels) Stimulates the kidneys and intestine absorb more calcium

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67 Figure 9.10 Hormonal controls of ionic calcium levels in the blood. Calcitonin Calcitonin stimulates calcium salt deposit in bone. Thyroid gland releases calcitonin. Stimulus: Rising blood Ca 2+ levels BALANCE Calcium homeostasis of blood: 9 11 mg/100 ml BALANCE Stimulus Falling blood Ca 2+ levels Osteoclasts degrade bone matrix and release Ca 2+ into blood. PTH Thyroid gland Parathyroid glands Parathyroid glands release parathyroid hormone (PTH) Pearson Education, Inc.

68 Adrenal Gland (2-in-1) Adrenal Cortex (3 groups of hormones) Hormonal stimuli Humoral stimuli Adrenal Medulla (2 hormones) Neural stimuli HW: Read / Take notes from text p Study all glands / hormones covered so far.

69 Adrenal Glands Sit on top of the kidneys Two regions: Adrenal cortex hormonal / humoral control produces 3 corticosteroids Mineralocorticoids Glucocorticoids Sex hormones Adrenal medulla neural control inner neural tissue region

70 Medulla Cortex Figure 9.11 Microscopic structure of the adrenal gland. Adrenal gland Kidney Capsule Mineralocorticoidsecreting area Adrenal gland Medulla Cortex Glucocorticoidsecreting area Adrenal cortex Kidney Sex hormone secreting area Adrenal medulla 2015 Pearson Education, Inc.

71 Adrenal Cortex Hormones Mineralocorticoids (mainly aldosterone) Produced in outer adrenal cortex Target organ: kidney Regulate sodium and potassium ion levels in blood Regulate water and electrolyte balance

72 Aldosterone Increases blood pressure by regulating kidney function Causes kidney to Reabsorb sodium Reabsorb water Secrete potassium Release stimulated by: Humoral stimulation level of K + ions in blood Hormonal stimulation (ACTH stress hormone) Inhibited by atrial natriuretic peptide (ANP) Heart-produced hormone when blood pressure is high

73 Figure 9.12 Major mechanisms controlling aldosterone release from the adrenal cortex. Decreased Na + or increased K + in blood Decreased blood volume and/or blood pressure Kidney ACTH Stress Hypothalamus Corticotropinreleasing hormone Anterior pituitary Increased blood pressure or blood volume Direct stimulating effect Renin Indirect stimulating effect via angiotensin Angiotensin II Heart Atrial natriuretic peptide (ANP) Inhibitory effect Mineralocorticoidproducing part of adrenal cortex Enhanced secretion of aldosterone targets kidney tubules 2015 Pearson Education, Inc. Increased absorption of Na + and water; increased K + excretion Increased blood volume and blood pressure

74 Glucocorticoids Cortisone and cortisol Produced by middle layer of adrenal cortex Promote normal cell metabolism Increases blood glucose levels (hyperglycemic) Helps resist long-term stressors Anti-inflammatory properties Released in response to increased ACTH in blood (hormonal stimulus)

75 Sex Hormones Androgens (male sex hormones, ex. testosterone) Some estrogens produced (female sex hormone) Produced in the inner layer of the adrenal cortex Small amounts are made throughout life Role in male development: Testes formation (early regulation) Spermatogenesis Inhibition of fat deposition Enlargement of skeletal muscle cells

76 Sex Hormones Effects of Testosterone

77 Adrenal Medulla Hormones Produces two similar hormones: (catecholamines) 1. Epinephrine (adrenaline) 2. Norepinephrine (noradrenaline) Fight or Flight Hormones Prepare the body to deal with short-term stress Increases: heart rate blood pressure blood glucose levels Dilates small passageways of lungs

78 Medulla Cortex Capsule Mineralocorticoid Secreting cells Glucocorticoid Secreting cells Sex hormone Secreting cells Adrenal medulla 2015 Pearson Education, Inc.

79 Figure 9.13 Roles of the hypothalamus, adrenal medulla, and adrenal cortex in the stress response. Short term Hypothalamus Nerve impulses Spinal cord Stress Releasing hormones Corticotropic cells of anterior pituitary More prolonged Adrenal medulla Preganglionic sympathetic fibers ACTH Adrenal cortex Mineralocorticoids Glucocorticoids Catecholamines (epinephrine and norepinephrine) 2015 Pearson Education, Inc. Short-term stress response Increased heart rate Increased blood pressure Liver converts glycogen to glucose and releases glucose to blood Dilation of bronchioles Changes in blood flow patterns, leading to increased alertness and decreased digestive and kidney activity Increased metabolic rate Long-term stress response 1. Retention of sodium and water by kidneys Increased blood volume and blood pressure Proteins and fats converted to glucose or broken down for energy Increased blood sugar Suppression of immune system

80 Regulation of Blood Glucose Levels Pancreas (hidden Islets of Langerhans) Pancreatic Islets (2 hormones) Humoral stimuli Beta cells Alpha cells HW: Read / Take notes from text p Complete Blood Glucose handout.

81 Pancreatic Islets Pancreas Located in the abdomen, close to stomach Mixed gland, with both endocrine and exocrine functions The pancreatic islets produce hormones Insulin produced by beta cells Glucagon produced by alpha cells These hormones are antagonists that maintain blood sugar homeostasis

82 Figure 9.14a Pancreatic tissue. Stomach Pancreas (a) 2015 Pearson Education, Inc.

83 Figure 9.14c Pancreatic tissue. Exocrine cells of pancreas Alpha (α) cells Capillaries 2015 Pearson Education, Inc. (c) Cord of beta (β) cells secreting insulin into capillaries

84 Pancreatic Islets Insulin Released when blood glucose levels are high Increases the rate of glucose uptake and metabolism by body cells Glucagon Released when blood glucose levels are low Stimulates the liver to release glucose to blood, thus increasing blood glucose levels

85 BioFlix : Homeostasis

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87 Figure 9.15 Regulation of blood glucose levels by a negative feedback mechanism involving pancreatic hormones. Insulin-secreting cells of the pancreas activated; release insulin into the blood Pancreas Elevated blood sugar level Insulin Tissue cells Glucose Glycogen Liver takes up glucose and stores as glycogen Uptake of glucose from blood is enhanced in most body cells Blood glucose falls to homeostatic set point; stimulus for insulin release diminishes Stimulus Blood glucose level (e.g., after eating four jelly doughnuts) Blood glucose rises to homeostatic set point; stimulus for glucagon release diminishes Stimulus Blood glucose level (e.g., after skipping a meal) Low blood sugar level Liver breaks down glycogen stores and releases glucose to the blood Glucose Glycogen Liver Glucagon Glucagon-releasing cells of pancreas activated; release glucagon into blood 2015 Pearson Education, Inc.

88 Diabetes mellitus Occurs in the absence of insulin Blood sugar levels increase dramatically Blood glucose is lost in the urine; water follows Three cardinal signs: 1. Polyuria production of abnormally large volumes of dilute urine. 2. Polydipsia excessive thirst 3. Polyphagia excessive hunger

89 Oral Glucose Tolerance Test

90 Pineal Gland (1 hormone) Neural stimuli Thymus (1 hormone) Humoral stimuli Gonads (endocrine function same as adrenal cortex) Testes (1 group, 1 main hormone) Ovaries (2 groups) Placenta (3 hormones) HW: Read / Take notes from text p Study all glands and hormones. Complete WB , 189

91 Figure 9.3 Location of the major endocrine organs of the body. Pineal gland Hypothalamus Pituitary gland Thyroid gland Parathyroid glands Thymus Adrenal glands Pancreas Ovary (female) Testis (male) 2015 Pearson Education, Inc.

92 Pineal Gland Located in the middle of the brain Stimulated by light Secretes melatonin Helps establish the body s sleep/wake cycles Establishes biological rhythms Coordinates fertility hormones in humans

93 Circadian Rhythms

94 Thymus Gland Located posterior to the sternum Largest in infants and children Produces thymosin Matures some types of white blood cells Important in developing the immune system

95 Gonads Ovaries Produce eggs Produce two groups of steroid hormones: 1. Estrogens 2. Progesterone Testes Produce sperm Produce androgens Ex. testosterone

96 Hormones of the Ovaries Estrogens Development of secondary female characteristics Mature female reproductive organs Progesterone Helps in the implantation of an embryo in the uterus Helps prepare breasts for lactation In combination, progesterone and estrogens Promote breast development Regulate menstrual cycle

97 Hormones of the Testes Produce several androgens Testosterone is the most important androgen Responsible for male secondary sex characteristics Promotes growth Promotes maturation of male reproductive system Required for sperm cell production

98 Testosterone levels Optimal vs. Low (exaggerated illustration)

99 Placenta Hormones maintain pregnancy Progesterone hcg (human chorionic gonadotropin) Estrogen Some hormones help during childbirth

100 Endocrine System Videos as Review Endocrine System Video Support Hormone song Watch the following videos to review the endocrine system, hormones and gland functions. CC Endocrine system part 1 A&P CC Endocrine system part 2 A&P CC Endocrine system Biology