Download Endocrine System: How Hormones Control Bodily Functions

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