Hormones of the Pancreas

8/9/2019 Hormones of the Pancreas

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The pancreas secretes:

yDigestive enzymes

yFour hormones

Insulin

Glucagon

Somatostatin

Pancreatic polypeptide



Insulin and glucagon are involved

in CARBOHYDRATEMETABOLISM

Somatostatin is involved in

LOCAL REGULATION OFINSULIN AND GLUCAGON

SECRETION

Pancreatic polypeptide affectsGASTROINTESTINAL

SECRETION



Contains 36 amino acids

Produced by the F cells of the pancreas Secretion is INCREASED during:

yHigh-protein diet

yFastingyExercise

y Acute hypoglycemia

Secretion is DECREASED bysomatostatin and intravenous infusion

of glucose

Function: UNKNOWN



A protein secreted by the cells of

the islets of LangerhansHas been isolated and crystallized

Crystalline insulin

yContains a small amount of ZINC

Small amounts of CHROMIUM are

needed for the synthesis of insulin

Amount of chromium in the body

decreases with age



It increases the rate of

oxidation of glucose

Facilitates the conversion of

glucose to glycogen in theliver and muscles

Increases the synthesis of

fatty acids, protein, and RNADecreases blood sugar to its

normal fasting level



HYPERGLYCEMIA

yIf the islets of Langerhans areunderactive or degenerated = little or no

insulin is produced

y Associated with diabetes mellitus

DIABETES MELLITUS

yBlood sugar level is increased

yGlucose appears in urine

yKetone bodies are formed accompanied

by acidosis

Insulin can NOT cure diabetes



It is NOT taken ORALLY

Given by subcutaneous injectionymust be given 2 or 3 times a day

to a patient with diabetes mellitus

PROTAMINE ZINC INSULINy Insulin is combined with protamin

yUtilized much more slowly

yEffective for more than 24 hrs.yOne injection daily



HYPOGLYCEMIA

y

Blood sugar level falls far below its normalfasting value

y Symptoms:

Dizziness

Nervousness Blurring of vision

Unconsciousness

y This state is called INSULIN SHOCK

y Relieved by administration of sugar

y Also occurs when there is a tumor on the

islets of Langerhans



Insulin is degraded primarily in the

LIVER and KIDNEYSyEnzyme: glutathione insulin

transhyroxylase

1 ml sterile solution contains 100units of insulin

1 unit of insulin can reduce the blood

sugar level of a normal 2-kg RABBITafter a 24-hr fast from 120 to 45 mg

per 100ml



Certain HYPOGLYCEMIC

SUBSTANCES lower the blood sugar

level

y Effective in adult diabetes and NOT juvenile

diabetes

yFunction: stimulates the cells of the islets of Langerhans to produce insulin

y Examples:

Glyburide (Micronase)

Troglitazone (Rezulin)

Metformin (Glucophage)

y Have many side effects



Former name: HYPERGLYCEMIC

GLYCOGENOLYTIC FACTOR(HGF)

Gave the hyperglycemic effects

from CRUDE INSULINHas been isolated and crystallized

A polypeptide containing 29 amino

acids in a single chain



Has a different arrangement of

amino acids than insulin

Contains NO disulfide bridges

Contains methionine andtryptophan (absent in insulin)

Does NOT contain cysteine,

proline, and isoleucine (presentin insulin)



Formed in the E cells of the islets

of LangerhansSignificant amounts also come

from the A cells in the stomach

and other parts of the GITCauses an increase in the sugar

content of the blood

yStimulates PHOSPHORYLASE ACTIVITY in the liver



Increases the formation of cAMP

y Activates phosphorylasey Increases the glucose content of the

blood

yCauses hyperglycemia Stimulates the formation of glucose

from amino acids (gluconeogenesis)

Increases the release of potassium

ions from the liver

Increases the breakdown of lipids to

fatty acids and glycerol



Has been used to treat:yHypoglycemic effects due to

an overdose of insulin

yInsulin shock

Used in the diagnostic test

for glycogen storagedisease



THYROID GLAND

yH-shaped

yConsists of one lobe on each

side of the trachea with a piece

of tissue connecting the two

lobes

yWeight: approximately 25 to 30 g

in adults



yFilled with many small follicles that

contain COLLOIDContains the thyroid gland¶s

hormones

yThe only endocrine gland in the

body that is capable of storing

appreciable amounts of hormones

yContains IODINE necessary for

the proper functioning of the body 2 forms of iodine in the body:

y Iodide ions and thyroid hormones



HORMONES of the thyroid gland:

yRegulate the metabolism of the bodyy Affect the growth and development of

the body

Methods for evaluating activityyold and indirect (replaced already)

Basal metabolic rate (BMR)

Protein-bound iodine (PBI)

Butanol-extractable iodine (BEI)

yNew, direct and stable

Radioimmunoassay methods



COLLOID of the thyroid contains

yTHYROGLOBIN / THYROGLOBULIN A glycoprotein

Liberates the principal thyroid

hormones; TRIIODOTHYRONINE (T3)

and THYROXINE (T4) T3 is the major active form of the

thyroid hormone and is 3 to 5 times

as biologically active as T4

.

Mono- and diiodothyronine are

formed but quickly deiodinated in the

bloodstream



CALCITONIN

(THYROCALCITONIN)

yProduced in the C cells in the

thyroid gland

yRegulates calcium ions in the blood

yPrevents calcium ion concentration

from rising above the required level

yPure calcitonin

1st isolated in 1968; structure wasdetermined shortly thereafter



y This is a polypeptide containing a

single chain of 32 amino acids

y Produces its effect by inhibiting the

release of calcium ions, from the bone

to the blood

y Its release is stimulated by high levelsof Ca2+ in the blood

yMEDULLARY THYROID CARCINOMA

A disorder of the C cells of the

thyroid

Causes an abnormally high

production of calcitonin



HYPOTHYROIDISM

y A condition in which the thyroid gland

does not manufacture sufficient thyroxine

for the body¶s needs

yUsually caused by a lack of iodine in thediet

yMay also be due to a disease of the

thyroid gland or to its congenital absence



ySymptoms:

SluggishnessWeight gain

Slower heartbeat

Reduced metabolic rateLoss of appetite

yRemedy: use iodized salt; use of

synthetic thyroid hormones



CRETINISM

y The thyroid gland is absent or fails todevelop in an infant

y CRETIN

Name of the individual with this condition

Has greatly retarded growth (physicallyand mentally)

Usually abnormal dwarves with coarse

hair and thick dry skin

Obese with protruding abdomens

Underdeveloped mentally and sexually



yRemedy: give thyroid hormones

y If thyroid gland atrophies after anindividual reaches adulthood:

Same symptoms of cretinism appear

but Individual remains adult in size

MYXEDEMA

yDevelopment of thick, coarse, dry skin

yCured by admission of thyroxine

yPeople are sluggish, have lower pulse

and metabolic rate and lower body

temperature and are frequently anemic.

They are also very sensitive to cold.



SIMPLE GOITER

y aka COLLOID GOITER or ENDEMIC

GOITERy A condition in which the thyroid gland

enlarges

y Due to lack of iodine in the diet

y The decreased production of thyroid

hormones causes an increased production

of TSH, which overstimulates the thyroid

gland

y Accompanied by a definite increase in the

amount of colloid material in the thyroid

gland

y

Neck size increases



HASHIMOTO¶S DISEASE

y A type of hypothyroidism in which allaspects of the thyroid function may

be impaired

yCaused by an attack on the thyroidgland by the body¶s own immune

system



HYPERTHYROIDISM

yOccurs when the thyroid glandproduces excess thyroxine

y Symptoms:

Increased metabolic rate Bulging of the eyes (exophthalmos)

Nervousness

Loss of weight

Rapid, irregular hearbeat

Elevated body temperature



y Also called GRAVE¶S DISEASE,

BASEDOW¶S DISEASE or

EXOPHTHALMIC GOITERy May also be due to a tumor in the thyroid

gland (TOXIC ADENOMA or PLUMMER¶S

DISEASE)

y Control or cure: Surgical removal of part of the thyroid

gland

Oral administration of radioactive iodine

Use of antithyroid drugs

y Hypertrophy of the endocrine glands

toxic adenomas with a malignant

potential if not treated promptly.



Parathyroid hormone:

y Influences the metabolism of

calcium and phosphorus in the body

y A polypeptide chain with 84 amino

acids

yCANNOT be stored in theparathyroid gland

ySynthesized and secreted

continuously Administration of VIT. A

decreases parathyroid hormone



HYPOPARATHYROIDISM

yCaused by the surgicalremoval of the parathyroid

glands

ySymptoms:

Muscular weakness

IrritabilityTetany



yThere is a decrease in the calcium

content of the BLOOD PLASMAyDeath due to convulsions

yCalcium content in URINE

decreases

yPhosphate content of the PLASMA

increases

yTreatment: (relieve the symptoms)

Vitamin D

Calcium salts

Or both



HYPERPARATHYROIDISM

y

An increase in the production of hormones by the parathyroid glands

yUsually caused by a tumor of those

glands (parathyroid adenoma)

y Symptoms: Decalcification of bones

Deformation and fractures of the bones

Nausea Polyuria

yDeposits of calcium occur in soft tissues

y

Renal stones frequently occur



yCalcium content of the BLOOD

PLASMA is high and thephosphate content is low

yExtra calcium in the blood is

obtained from the bonesyUrine calcium, phosphate and

cAMP are increased

yTreatment:Surgical removal of the tumor

of the parathyroid glands

Hormones of the Pancreas

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