A&p 2 Lecture: Chapter 16: The Endocrine System

Front 1

What does the endocrine system do?

Back 1

It interacts with the nervous system to coordinate and integrate the activity of body cells.

Front 2

What are hormones?

Back 2

Chemical messengers released into the blood by the endocrine system to influence metabolic activity.Usually long distance messengers

Front 3

Endocrinology is the study of ________________?

Back 3

The scientific study of hormones and the endocrine organs.

Front 4

Processes controlled by hormones are?

Back 4

reproduction, growth, development, body defenses, electrolyte balance, water balance, and cell metabolism

Front 5

Exocrine glands

Back 5

Produce nonhormonal substances such as sweat and saliva; have ducts which are routed to the membrane surface

Front 6

Endocrine glands

Back 6

"ductless glands"
produce hormones and lack ducts; release hormones into surrounding tissue fluid

Front 7

Endocrine glands include these?

Back 7

pituitary, thyroid, parathyroid, adrenal, pineal, thymus glands, pancreas, testes, ovaries

Front 8

Hypothalamus

Back 8

along with its neural functions produces and releases hormones, considered a neuroendocrine organ

Front 9

Autocrines

Back 9

Chemicals that exert their effects on the same cells that secret them ex. prostaglandins

Front 10

Paracrines

Back 10

also act locally but affect cell types other than those releasing the paracrine chemicals

Front 11

Hormones are classifed into two groups

Back 11

Amino based
Steroid based

Front 12

Amino based hormones

Back 12

Molecule sizes varies, from simple (amines and thyroxine), to peptide chains, and proteins

Front 13

Steroid based hormones

Back 13

Synthesized from cholesterol,
Only gonadal and adrenocortical hormones are steroid based

Front 14

Eicosanoids

Back 14

include leukotrienes and prostaglandins. Are biologically active lipids and are released by nearly all cell membranes. Do not fit the criteria for true hormones since they affect only nearby cells.

Front 15

Leukotrienes

Back 15

Are signaling chemicals that mediate inflammation and some allergic reactions.

Front 16

Prostaglandins

Back 16

Have multiple targets and effects, ranging from raising blood pressure, increasing uterine contractions, and enhancing clotting, and pain.

Front 17

Target cells

Back 17

Certain tissue cells that a given hormone influences- by altering that cell's activity by decreasing or increasing the rates of normal cellular processes

Front 18

Cell responses to hormone stimulation may include?

Back 18

Changes in membrane permeability, enzyme synthesis, activation, or inhibition, secretory activity, gene activation, and mitosis

Front 19

How do water soluble (all amino based hormones except thyroid hormone) hormones work?

Back 19

By acting on receptors in the plasma membrane via G proteins to one on more intracellular second messengers which mediate the cell's response

Front 20

How do lipid soluble (steroid and thyroid hormones) work?

Back 20

They act on intracellular receptors, directly activating genes- since these can enter the cell being lipids

Front 21

Cyclic AMP Signaling Mechanism

Back 21

1. The hormone (acting as the 1st messenger) binds to its receptor
2. Hormone binding causes the receptor to change shape, allowing it to bind to a nearby inactive G-protein
3. The activated G-protein moves along the membrane and binds to the effector enzyme adenylate cyclase
4. If activated, adenylate cyclase generates the second messenger cAMP from ATP
5. cAMP is free to diffuse within the cell triggers chemical reactions

Front 22

Protein kinases

Back 22

Enzymes that add a phosphate group to various proteins which activates some proteins and inhibits others

Front 23

PIP- Calcium Signal Mechanism

Back 23

Intracellular calcium ions act as the final mediator, involves phosphatidyl inositol.
Is an important second messenger system

Front 24

How do steroid hormones affect cells?

Back 24

They enter their target cells and effect responses by activating DNA, which initiates messenger RNA formation leading to protein synthesis

Front 25

Target cell activation by hormone-receptor interaction depends on?

Back 25

1. Blood levels of the hormones
2. Relative numbers of receptors for that hormone on or in the target cells
3. Affinity (strength) of the bond between the hormone and the receptor

Front 26

Hormone receptors

Back 26

Are dynamic structures. Changes in number and sensitivity of hormone receptors may occur in response to high or low levels of stimulating hormones

Front 27

Up-regulation

Back 27

Target cells form more receptors in response to rising blood levels of the specific hormones to which they respond

Front 28

Down-regulation

Back 28

Loss of receptors and prevents the target cells from overreacting to persistently high hormone levels

Front 29

Concentration of a circulating hormone depends on?

Back 29

Its rate of release and the speed at which it is inactivated and removed from the body

Front 30

Half-life

Back 30

Length of time for a hormone's blood level to be decreased by half. Water-soluble hormones exhibit the shortest half-lives

Front 31

Permissiveness

Back 31

Situation when one hormone cannot exert its full effects without another hormone being present
Ex. Thyroid hormone is necessary for the timely development of reproductive structures along with the reprod. hormones

Front 32

Synergism

Back 32

Situations when more than one hormone produces the same effects at the target cell and the combined effects are amplified
Ex. Glucagon and epinephrine cause the liver to release about 150% more when they act together

Front 33

Antagonism

Back 33

When one hormone opposes the action of another hormone
Ex. Insulin (lowers blood sugar)+ Glucagon (raises blood sugar)

Front 34

Negative feedback system

Back 34

Hormone secretion is triggered by some internal or external stimulation and as hormone levels rise, they cause target organ effects and inhibit further hormone release

Front 35

Humoral Stimuli

Back 35

Endocrine glands secrete their hormones in direct response to changing blood levels of certain critical ions and nutrients. The simplest of the endocrine control systems. Ex. PTH and calcium, insulin is also released in response to humoral stimuli

Front 36

Neural Stimuli

Back 36

Nerve fibers stimulate hormone release
Ex. SNS stimulation of the adrenal medulla to release norepinephrine and epinephrine during periods of stress

Front 37

Hormonal Stimuli

Back 37

Many endocrine glands release their hormones in response to hormones produced by other endocrine organs, the stimuli being hormonal stimuli
Ex. the hypothalamic-pituitary-target endocrine organ feedback loop p. 611

Front 38

Nervous System Modulation

Back 38

Both hormonal, humoral, and neural stimuli and feedback inhibition may be modified by the nervous system. Nervous system makes certain adjustments to maintain homeostasis by overriding endocrine controls

Front 39

Pituitary Gland

Back 39

"hypophysis"
located in sella turcica of the sphenoid bone, secretes at least 9 hormones, has two major lobes- one is neural the other is glandular

Front 40

Posterior Pituitary

Back 40

Composed of pituicytes (glia-like supporting cells and nerve fibers), releases neurohormones. Is a hormone storage area and not a true endocrine gland

Front 41

Neurohormones

Back 41

hormones secreted by neurons

Front 42

Neurohypophysis

Back 42

consists of the posterior lobe of the pituitary and the infundibulum

Front 43

Anterior pituitary lobe

Back 43

"adenohypophysis," composed of glandular tissue and it makes and releases a number of hormones

Front 44

Hypothalamic-hypophyseal tract

Back 44

a nerve bundle that runs through the infundibulum that connects the posterior lobe with the hypothalamus

Front 45

Supraoptic and paraventricular nuclei

Back 45

located in the hypothalamus, contain neurons that give rise to the hypothalamic-hypophyseal tract

Front 46

What is the Primary capillary plexus?

Back 46

located in the infundibulum, communicates inferiorly via the small hypophyseal portal veins with the secondary capillary plexus in the anterior lobe

Front 47

Hypophyseal portal system

Back 47

Consists of the primary and secondary capillary plexuses and the intervening hypophyseal portal veins

Front 48

What does the hypothalamus do?

Back 48

1. Regulates the hormonal output of the anterior pituitary via releasingand inhibiting hormones 2. Synthesizes two hormones that it exports to the posterior pituitary for storage and later release

Front 49

Pro-opiomelanocortin (POMC)

Back 49

an adenohypophyseal hormone, a large molecule that can be split enzymatically into one or more active hormones, the source of adrenocorticotropic hormone and melanocyte-stimulating hormone

Front 50

Tropins or tropic hormones

Back 50

includes 4 of the 6 anterior pituitary hormones- thyroid stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, and luteinizing hormone. They regulate the secretory action of the endocrine glands. All affect their target cells via a cyclic AMP second messenger system

Front 51

Growth hormone (GH)
see p.618

Back 51

anabolic hormone that stimulates growth of all body tissues especially skeletal and bone. GH mobilizes fats, stimulates protein synthesis, and inhibits glucose uptake and metabolism. Secretion is regulated by GH releasing hormone (GHRH) and GH inhibiting hormone (GHIH)

Front 52

Hyposecretion of GH and Hypersecretion of GH results in what?

Back 52

hypersecretion results in gigantism in kids and acromegaly in adults
hyposecretion in kids results in pituitary dwarfism

Front 53

Thyroid-stimulating hormone (TSH)

Back 53

chemical structure- glycoprotein, cell type- thyrotroph.
Promotes normal development and activity of the thyroid gland. TRH (thyrotropin releasing hormone) stimulates release and negative feedback loop of TH inhibits it

Front 54

Hyposecretion and Hypersecretion of TSH

Back 54

Hyposecretion results in cretinism in kids and myxedema in adults, hypersecretion results in hyperthyroidism similar to Grave's disease

Front 55

Adrenocorticotropic hormone (ACTH)
chemical structure- polypeptide of 39 amino acids
cell type- corticotroph

Back 55

Stimulates the adrenal cortex to release corticosteriods. ACTH release is triggered by corticotropin-releasing hormone (CRH) and inhibited by rising glucocorticoid levels

Front 56

Gonadotropins

Back 56

include the follicle-stimulating hormone (FSH) and luteinizing hormone (LH). They regulate the function of the testes and ovaries. Stimulated by the gonadtropin-releasing hormone (GnRH) and gonadal hormones feed back to suppress FSH and LH release

Front 57

Prolactin

Back 57

Produced by the lactotrophs, stimulates milk production. Prolactin-inhibiting hormone (PIH) known to be dopamine prevents prolactin secretion, whereas, prolactin-releasing hormone (PRH) stimulates release

Front 58

Posterior pituitary hormones

Back 58

stored hormones are the antidiuretic hormone and oxytocin

Front 59

Oxytocin

Back 59

a strong stimulant of uterine contractions and milk ejection in women, its release is mediated reflexively by the hypothalamus and represents a positive feedback mechanism

Front 60

Antidiuretic hormone (ADH)

(vasopressin)

Back 60

stored in posterior pituitary, stimulated by impulses from hypothalamic neurons in response to increased osmolality of blood or decreased blood volume. Inhibited by adequate hydration of the body and by alcohol. Major affect- the kidney

Front 61

Hyper and hyposecretion of ADH

Back 61

hyposecretion= diabetes insipidus
hypersecretion= syndrome of inappropriate ADH secretion (SIADH)

Front 62

Thyroid gland

Back 62

butterfly shaped, located in the anterior neck, on the trachea just inferior to the larynx. Isthmus connects the 2 lateral lobes. Largest pure endocrine gland in the body.

Front 63

Thyroid follicles

Back 63

Store colloid containing thyroglobulin, a glycoprotein from which thyroid hormone is derived

Front 64

Thyroid hormone

Back 64

consists of 2 iodine containing amine hormones (thyroxine T4) and triiodothyronine (T3, affects every cell in the body except for the adult brain, spleen, testes, uterus, and the thyroid gland itself.

Front 65

Calorigenic effect

Back 65

TH's effect of increasing basal metabolic rate and body heat production

Front 66

Thyroid hormone effects

Back 66

Maintains blood pressure, regulator of tissue growth and development, critical for normal skeletal and nervous system development and maturation and for reproductive capabilities

Front 67

Thyroid hormone synthesis

Back 67

Begin when TSH secreted by the anterior pituitary binds to follicle cell receptors

Front 68

Steps of thyroid hormone synthesis

Back 68

1. Formation and storage of thyroglobulin 2. Iodine trapping 3. Oxidation to iodine and iodination 4. Coupling of T2 and T1 5. Colloid endocytosis 6. Cleavage of the hormones for release

Front 69

Myxedema

Back 69

hypothyroid syndrome, "mucous swelling" results in a goiter if caused by a lack of iodine

Front 70

Calcitonin

Back 70

a polypeptide hormone produced by the parafollicular or C cells of the thyroid gland, most important effect is to lower blood Ca 2+ levels, is a direct antagonist of the parathyroid hormone. It inhibits osteoclast activity and it stimulates Ca2+ uptake and incorporation into bone matrix

Front 71

Parathyroid glands

Back 71

Located on the dorsal aspect of the thyroid gland, they secrete parathyroid hormone (PTH) which causes an increase in blood calcium levels by targeting bone, the intestine, and the kidneys, is the antagonist to calcitonin

Front 72

PTH release

Back 72

Is triggered by falling blood calcium levels and is inhibited by rising calcium levels

Front 73

Hypersecretion and hyposecretion of PTH

Back 73

Hypersecretion= hypercalcemia and all its effects and in extreme bone wasting
Hyposecretion= leads to hypocalcemia, evidenced by tetany and respiratory paralysis

Front 74

Adrenal glands

Back 74

Pyramid shaped organs perched atop the kidneys also known as the suprarenal glands, consists of the inner adrenal medulla and the outer adrenal cortex

Front 75

Corticosteroids

Back 75

Steroid hormones that are synthesized from cholesterol by the adrenal cortex

Front 76

Zona glomerulosa

Back 76

outer layer of the adrenal cortex, Cell clusters that produce the mineralocorticoids are hormones that help control the balance of minerals and water in the blood

Front 77

Zona fasciculata

Back 77

middle layer of adrenal cortex, produce the metabolic hormones called glucocorticoids

Front 78

Zona reticularis

Back 78

innermost layer of adrenal cortex, produce small amounts of adrenal sex hormones or gonadocorticoids

Front 79

Mineralcorticoids

Back 79

Regulate the electrolyte (mineral salt)concentrations in extracellular fluids, particularly of Na and K

Front 80

Aldosterone

Back 80

The most potent mineralcorticoids, and accounts for 95% of the mineralcorticoids produced. Reduces excretion of Na+ from the body and enhances Na+ reabsorption from sweat, saliva, and gastric juice

Front 81

Releasing and inhibiting of aldosterone

Back 81

stimulated by the renin-angiotensin mechanism, rising potassium ion or falling sodium levels in the blood, and ACTH. Aldosterone is inhibited by atrial natriuretic peptide

Front 82

Hyper and hypo secretion of aldosterone

Back 82

Hypersecretion results in aldosteronism which causes hypertension and edema due to excessive Na+ and water retention and accelerated excretion of potassium ions
Hyposecretion results in Addison's disease.

Front 83

Glucocorticoids

Back 83

Influence the energy metabolism of most body cells and help us to resist stressors. They keep blood sugar levels fairly constant, and maintain blood pressure by increasing the action of vasoconstrictors. Include cortisol, cortisone, and corticosterone. Only cortisol is secreted in significant amounts in humans. ACTH is the major stimulus for glucocorticoid release.

Front 84

Cushing's syndrome

Back 84

Most often caused by large doses of glucocorticoid drugs. Symptoms- hyperglycemia, losses in muscle and bone protein, water and salt retention, swollen face and buffalo hump.

Front 85

Addison's disease

Back 85

Major hyposecretory disease of the adrenal cortex, usually involves deficits in both glucocorticoids and mineralocorticoids

Front 86

Gonadocorticoids

Back 86

sex hormones, mainly androgens, are produced in small amounts throughout life

Front 87

Adrenal medulla

Back 87

Produces catecholamines (epinephrine and norepinephrine) in response to sympathetic nervous system stimulation. Its catecholamines enhance and prolong the fight or flight response to short term stressors. Hypersecretion leads to symptoms typical of sympathetic nervous system overactivity.

Front 88

Pancreas

Back 88

Mixed gland of both endocrine and exocrine gland cells, Acinar cells produce enzyme rich juice that is ducted into the small intestine during food digestion

Front 89

Pancreatic islets (islets of Langerhans)

Back 89

tiny cell clusters that produce pancreatic hormones. They contain two major types of hormone producing cells- alpha cells and beta cells

Front 90

Alph and beta cells of the pancreas

Back 90

Secrete glucagon and insulin appropriately during the fasting and fed states

Front 91

Glucagon

Back 91

Released by alpha cells,29 amino acid polypeptide, is a very potent hyperglycemic agent. Its major target is the liver where it promotes 1. Breakdown of glycogen to glucose
2. Synthesis of glucose from lactic acid and from noncarbohydrate molecules 3. Release of glucose to the blood by liver cells, which causes blood glucose levels to rise.

Front 92

Insulin

Back 92

Released by beta cells when blood levels of glucose and amino acids are rising. It increases the rate of glucose uptake and metabolism by most body cells. Hyposecretion of insulin results in diabetes mellitus. Symptoms are polyuria, polydipsia, and polyphagia.

Front 93

Polyuria

Back 93

A huge urine output that results in decreased blood volume and dehydration

Front 94

Polydipsia

Back 94

Excessive thirst

Front 95

Polyphagia

Back 95

Excessive hunger and food consumption

Front 96

Ketones

Back 96

fatty acid metabolites, are organic acids. Blood pH drops when they accumulate in the blood= ketoacidosis

Front 97

Gonads

Back 97

Produce steroid sex hormones, include the ovaries and testes

Front 98

Estrogens

Back 98

Produced in the ovaries, promote breast development, secondary sex characteristics, and cyclic changes in the uterine mucosa, work together with progesterone to establish the menstrual cycle

Front 99

Testosterone

Back 99

Produced by the testes, promotes maturation of the male reproductive organs, development of secondary sex characteristics, and production of sperm in the testes

Front 100

Progesterone

Back 100

Released in response to high blood levels of LH

Front 101

Pineal Gland

Back 101

Hangs from the roof of the third ventricle in the diencephalon. Its secretory cells are the pinealocytes. Secrete melatonin

Front 102

Melatonin

Back 102

Influences daily rhythms and may have an antigonadotropic effect in humans

Front 103

Thymus

Back 103

Located in the upper thorax, declines in size and function as we age. Its hormones, thymosins, thymic factor, and thymopoietins, are important to the normal development of the immune response.

Front 104

Other hormone producing structures

Back 104

Heart- (atrial natriuretic peptide), gastrointestinal tract organs- (gastrin, secretin, and others), placenta- (estrogens and progesterones), kidneys (erythropoietin and renin), skin (cholecalciferol), and adipose tissue (leptin and resistin)

Front 105

Endocrine glands origination

Back 105

Are derived from all 3 germ layers. Those derived from mesoderm produce steroidal hormones, the others produce the amino acid- based hormones

Front 106

Menopause

Back 106

The natural decrease in function of the female's ovaries during late middle age

Front 107

Efficiency of endocrine glands as we age.

Back 107

Efficiency seems to decrease gradually, leading to increase in incidence of diabetes and a lower metabolic rate

Front 108

The Endocrine System

Back 108

Works with Nervous System
Lacks anatomical continuity
Weighs less than a pound

Front 109

Anterior Pituitary

Back 109

GH Growth Hormone
PRO Prolactin
TSH Throid Stimulating Horm.
ACTH Adrenocorticotropic Hor
FSH Follice Stimulating Horm
LH Luteinizing Hormone
ICSH Interstitial cell stimulating Horm

Front 110

Posterior Pituitary

Back 110

Hormones produce by Hypothalamus
Oxytocin
Anitdiuretic hormone

Front 111

Endocrine Glands

Back 111

-No ducts
-They secrete directly into body fluid
-Hormones typically circulate throughout the body
-There are exceptions

Front 112

Other organs with Endocrice functions

Back 112

pancreas
ovaries
testes
hypothalamus
small intestine
stomach
kidney
placenta
heart

Front 113

Significant things controlled by hormones

Back 113

reproduction
development
stress reactions
fluid/electrolyte balance
cellular metabolism

Front 114

Hormone

Back 114

endocrine messages are in the form of chemicals called hormone
hormon - to excite

Front 115

Chemistry of Hormones

Back 115

all are organic
2 chemical groups
-amino acids/proteins - some are simply altered amino acids(adrenalin and thyroxin) others aer short(ADH) or long(insulin chains of amino acids
-Steroids -all are similar complex ring forms made from cholesterol. All sex hormones and all products of the adrenal cortex

Front 116

Target Cells

Back 116

Cell that react and have specific receptors for specific hormones

Front 117

Mechanisms of Hormone Action
A hormone typically brings about one or more of these effects

Back 117

-permeability changes
-protein synthesis
-enzyme activation/suppression
-secretion
-mitosis

Front 118

Hormone levels are usually controlled by

Back 118

Negative Feedback Mechanisms

Front 119

Diabetes Insipidus

Back 119

ADH

Front 120

Diabetes mellitus(DM)

Back 120

-endocrine disorder of most concern
-syndrome:hyperglycemia, ketoacidosis or coma
-maybe as many as 5% in USA have DM
-3rd on the list of killer diseases

Front 121

complications of DM

Back 121

retinopathy
nephropathy
atherosclerotic coronary
peripheral arterial disease
peripheral and autonomic neuropathies

Front 122

Type I IDDM

Back 122

-usually young
-usually thin
-most serious
-only 5-10% or total
-prone to ketosis, microangiopathy, gangrene, blindness, impotence
-maybe autoimmune due to viral induce changes or molecular mimicry
-insulin injections are vital

Front 123

Type II NIDDM

Back 123

-Usually mature
-80% are obese
-causes are genetic and or obestiy
-atherosclerosis
-diet, exercise and or oral hypoglycemics are treatment for NIDDM

Front 124

IGT Imparied Glucose Tolerance

Back 124

Usually not serious
has been called borderline latent, chemical, symptomless

Front 125

Gestational Diabetes GDM

Back 125

80% become NIDDM within 20 years

Front 126

Stress

Back 126

The concept of stress is somewhat intangible; it is however related to any deviation from homeostasis

Front 127

Specific stimuli lead to specific response

Back 127

Examples
In stress type reactions this does not hold true

Front 128

GAS General Adaptation Syndrome

Back 128

the same syndrome of responses may occur regardless of the stress or the term used to describe these reponses

Front 129

Things to mention when talking to a person who is distressed, depressed, or displeased with life

Back 129

-liking oneself - min guilt
-doing stimulating things
-knowing oneself
-need for secure niche
-be good to others
-intimate relationship
-appreciation of simple things
-planning and preparing
-have enjoyable work
-not fighting with inevitable

Front 130

We all need some stress but too much may lead to ...

Back 130

hyypertension
allergic reations
ulcers
heart attacks
neuroses
phychoses
nervous break down
suicide

Front 131

Fators that may influence how one reacts to stressors include

Back 131

health
age
sex
nationality
past experience

Front 132

Measurable stress has been noted in

Back 132

test pilots
persons on death row
students taking test
psychotics

Front 133

THe hypothalamus monitors the body for stressors. In response it activates to mechanisms

Back 133

1-the alarm reaction
2-resistance reaction

Front 134

THe alarm reaction

Back 134

-involves the sympathetic nervous system and the adrenal medulla
-SNS immediately speeds things up
-adrenalin prolongs SNS responses

Front 135

The resistance reaction

Back 135

-slower and more prolonged
-CRH stimulates anterior pituitary A.P. releases ACTH
-ACTH stimulates adrenal cortex
-A.C. releases cortisol and aldosterone
-body is supportd for increased activity over a period of time

Front 136

Exhaustion Stage

Back 136

follows prolonged stress
the body cannot continue indefinitely to work at high stress capacity
-cortisol level may be depleted
hypokalemia may lead to cell death
-organs may fatigue and fail