Endocrine System: How Hormones Control Bodily Functions


Objectives of Chapter

•     Describe the general function of va...
Prolactin (PRL)

•     promotes secretion of milk from mammary glands


Thyroid Stimulating Hormone
Adrenocorticotropic Ho...
•     Adrenal Medulla (table 13.10)
            o      Metabolic rate Increases



Pancreas (table 13.12)

Glucagon – help...
Hyperthyroidism
•     ↑ metabolic rate

•     sensitive to heat, hyperactivity, weight loss
•     Graves Disease – auto-an...
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Endocrine System: How Hormones Control Bodily Functions

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Endocrine System: How Hormones Control Bodily Functions

  1. 1. Endocrine System: How Hormones Control Bodily Functions Objectives of Chapter • Describe the general function of various hormones • What do they do? What inhibits or stimulates their release? • Name the glands the hormones are released from • Explain how hormones exert their effects on target cells • Review diseases associated with excessive or deficient hormone secretion Endocrine System • Endocrine system - cells, tissues, organs (glands) secrete “hormones” into body fluids (ie blood stream) • Exocrine glands - into ducts • Functions 1. regulate metabolic processes; 2. aid in transporting substances through cell membranes; 3. regulate water balance 4. reproduction, development & growth Hormone Action & Type • Hormones work on “target cells” • Steroid hormones; lipid based, derived from cholesterol Amine/peptides/protein; Glycoproteins Action of Steroid Hormones (fig. 13.5; p. 473) • Action of Non-Steroid Hormones Control of Hormonal Secretions • Hypothalamus; tropic hormones; neural control • pituitary (“master”) gland • Changes in internal environment • ie – hydration states are detected and series of events cause water retention • Nervous system • Negative feedback system Hormones of Anterior Pituitary Gland (table 13.6; p. 485) Growth hormone (GH) • Stimulates ↑ in size & rate of reproduction of body cells • ↑ movement of A.A. into cells; protein synthesis; ↑ fat utilization, decreases glucose use; Promotes growth of long bones • Stimulated by: sleep, protein deficiency, low blood glucose, high intensity exercise • Abnormal secretion: dwarfism vs acromegaly, bovine growth hormone (milk) Follicle-stimulating hormone (FSH) • develop. egg-containing follicles in ovaries; stimulates secretion of “estrogen”; males, stim. production of sperm cells Luteinizing hormone (LH) • promotes secretion of sex hormones; estrogen, testosterone; releases egg cell in females • Levels of both ↑ at puberty • **together are called “gonadotropins”
  2. 2. Prolactin (PRL) • promotes secretion of milk from mammary glands Thyroid Stimulating Hormone Adrenocorticotropic Hormone (ACTH) Posterior Pituitary Hormones Oxytocin • contracts muscles in uterine wall & milk-secreting glands; controlled by stretch in uterine & vaginal walls, & stimulation of breasts Antidiuretic hormone (ADH) • causes kidneys to ↓ water excretion; can ↑ blood pressure ; controlled by plasma concentration & blood volume • osmorecptors in hypothalmus, stretch receptors in blood vessels Hormones of Thyroid Gland (table 13.7; p. 487) • Thyroxine (T4) • metabolism of carbs, fats, & protein; ↑ protein synthesis; accelerates growth; stimulates nervous system Triiodothyronine (T3) o same as above; more potent; **both have affects on metabolism Calcitonin • ↓ blood calcium levels by inhibiting release from bone; ↑ deposition in bone • controlled by blood calcium levels Parathyroid Glands • Secretes Parathyroid Hormone (PTH); Opposite effects of calcitonin • ↑ Ca++ levels in blood; Releases Ca++ from bone; Conserves Ca++ at kidneys; Influences vitamin D to help small intestine absorb Ca++ Adrenal Glands (table 13.11 & 13.10) Adrenal cortex • aldosterone; cortisol; Sex hormones – “adrenal androgens” Adrenal Medulla • epinephrine; *norepinephrine Adrenal Cortex (figure 13.31) • Aldosterone; causes kidney to conserve Na+ & excrete K+; retains water • responds to ∆’s in composition of blood; stimulated by ACTH Adrenal Cortex (figure 13.33) • Cortisol • maintain glucose levels; inhibits protein synthesis; promotes fat breakdown; stimulates liver to make glucose from A.A. & glycerol (gluconeogenesis) • *control inflammation Factors causing secretion: • prolonged exercise, low blood sugar levels, excessive stress Adrenal Medulla • 2 Hormones • Epinephrine (adrenalin); *Norepinephrine; *together know as catecholamines; Effects resemble result of sympathetic nerve fibers • “fight or flight” Epinephrine primary hormone • Release stimulus comes from nerve fibers from hypothalamus in response to “stress”
  3. 3. • Adrenal Medulla (table 13.10) o Metabolic rate Increases Pancreas (table 13.12) Glucagon – helps to ⇑ blood glucose • stimulated by ⇓ blood glucose • glycogenolysis (liver); lipolysis (adipose cell); gluconeogensis in liver Insulin – helps to ⇓ blood glucose • stimulated by ⇑ blood glucose • allows glucose, fats, & amino acids to move into all cells • muscle & liver - glycogen, triglyceride, protein • adipose cell - triglyceride (promotes storage of fat) • inhibits gluconeogensis Other Endocrine Glands • Pineal gland – (brain) • melatonin – inhibited by light & stimulated by darkness • involved in “circadian rhythms”; female reproductive cycle; ? (seasonal affective disorders) Thymus gland • secretes thymosin; production of white blood cells (immunity) Reproductive glands • ovaries – estrogen & progesterone • testes - testosterone Conditions Associated with Abnormal Secretions of These Hormones What Happens When the Body Does Not Produce and Release these Hormones Properly?? Special Topics involving the Endocrine System • Diabetes mellitus (hormone relationship “insulin”); difficulty maintaining blood glucose levels • Type 1 (insulin-dependent); 15% of diabetics, usually before 20 yrs • autoimmune response destroying pancreatic cells which produce insulin (beta cells); require insulin injections • Type 2 (non-insulin-dependent) • 85% of diabetics, usually after age of 40 (not any more though), associated with obesity • Receptors on cells are damaged & don’t respond to insulin • Treatment - monitor carbohydrate intake, exercise, weight loss, possibly medication Growth Hormone • Excessive Release; may caused by tumor on anterior pituitary • gigantism vs acromegaly • Too little Release; initially used to treat medical conditions (dwarfism) Human Growth Hormone (hGH) • many times used in combo. with steroids to enhance muscle size; ↑ connective tissue (strength gains don’t parallel muscle size gains) • is illegal w/o prescription!! • hGH secretion with aging causing • ↓ lean tissue & fat mass • Aging effect reversed by exogenous GH supplementation?? (negative side effects) Abnormal Thyroid Hormone Levels
  4. 4. Hyperthyroidism • ↑ metabolic rate • sensitive to heat, hyperactivity, weight loss • Graves Disease – auto-antibodies over-stimulate thyroid gland • goiter Hypothyroidism • ↓ metabolic rate • sensitive to cold, sluggish, weight gain • In children (Cretinism) • stunted growth, mental retardation • Hashimoto’s disease Disorders of Parathyroid Glands (table 13.8) Hyperparathyroidism • depresses nervous system • bone weakening • fatigue, depression o *why would it do the above???? • usually caused by tumor Hypoparathyroidism • excites nervous system • muscle cramps & seizures, diminishes blood calcium ion concentration • usually caused by inadvertent surgical removal; injury Special Topics Involving the Endocrine System Addison’s disease • adrenal cortex doesn't secrete sufficient hormones (autoimmune disease) • low blood glucose levels (hypoglycemia), ⇓ Na+, K+, dehydration, fatigue, low blood pressure Cushing’s disease • over secretion of ATCH & cortisol • due to corticosteroid drugs for many years, tumor on adrenal gland • characterized by muscle wasting, ↑ blood glucose levels & blood pressure • moon face (adipose tissue deposition), masculinized females due to ↑ sex hormone release Special Topics in Endocrine System • Diabetes Insipidus • impaired ADH function • either receptors or hypothalamus • prevents proper water regulation (constantly excrete water)

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