Metabolism Regulation

Metabolism Regulation

GlandsThree glands control metabolism:1. Thyroid gland

2. Parathyroid gland

3. Anterior pituitary

Thyroid Glandregulates glucose

metabolism

regulates growth and tissue differentiation

Where is it located?base of neck, anterior

to larynx

Thyroid Gland

Thyroid HormonesProduces two hormones:

1. thyroxine (T4)

2. iodothyronine (T3)

Thyroid Hormone RegulationWhat is the signal to indicate that thyroid hormone

levels should be changed?change in metabolic rate

What detects this change?hypothalamusreleases thyroid-releasing hormone (TRH) to signal to

the pituitary

What does TRH do?signals pituitary to release thyroid stimulating hormone

(TSH)

Thyroxine Regulationdecreased metabolism

hypothalamus pituitary gland to release TSH

decreased blood sugar

thyroid gland to release thyroxine

TRH

increase sugar metabolism

Thyroid Hormone Regulationhyperthyrodism = high thyroxine release

Cause:“hot” nodules / Grave’s disease (whole thyroid)

Symptoms:high glucose metabolism

weight loss with increased appetite anxiety increased heat release

Treatment:suppressive medication

Thyroid Hormone Regulationhypothyroidism = low thyroxine release

Causes:iodine deficiency

Symptoms:low glucose metabolism

weight gain fatigue decreased heat release

Treatment:synthetic hormone medication

Thyroid Disorders: GoitersWhy is table salt iodized?

low iodine levels result in enlarged thyroid glands - goiter

Thyroid Disorders: ThyrotoxicosisCause:

increased thyroid activity

Symptoms:similar to hyperthyroidismbulging eyesgoiter

Treatment:suppressive medicationradioactive iodine therapy (localized radiation)

Blood Calcium Regulation

CalciumWhere is calcium stored?

99% of calcium stored in bones for structure

Roles of calcium:1. required for muscle contraction2. important in neuronal communication3. bone structure maintenance

Bone Structureliving bones are complex

tissues

osteoblasts – cell which build bones

osteoclasts – cells which break down bones (release calcium)

Parathyroid Glandssmaller glands within

the thyroid gland

responsible for increasing Ca2+ levels in blood

produces parathyroid hormone (PTH)

Calcium Level Regulationhypocalcemia

parathyroid gland release PTHincreased Ca2+ levels

increased Ca2+ uptake in intestines (diet) &

kidneys (reabsorption)

increases osteoclast activity

activation of vitamin D; required for Ca2+ absorption

Calcium Level Regulationdifferent organ and hormone responsible to

decrease high calcium levels

organ = thyroid

hormone = calcitonin

Calcium Level Regulationhypercalcemia

thyroid gland release calcitonindecreased Ca2+ levels

inhibits Ca2+ absorption by intestines

decreases osteoclast activity

Parathyroid Disorders

Two types of parathyroid disorders:1. hypoparathyroidism2. hyperparathyroidism

HypoparathyroidismCauses:

absent parathyroid from birthaccidental removal upon thyroid removal

Symptoms:decreased Ca2+ levels in bloodsensitive nervesuncontrollable spasms of the limbs

Treatmentdaily calcium and vitamin D supplements

HyperparathyroidismCauses:

tumors on the parathyroid gland

Symptoms:kidney stonesaches & painsosteoporosisdepression & fatigue

Treatment:removal of parathyroid tissue