Friday, 24 SeptemberCh 11 Endocrine System

• The Hypothalamus and Pituitary Glands– Unique anatomy– Long & short loop negative feedback

• Stress and Cortisol

• Some examples of endocrine disorders

1QQ # 8 for 8:30 class1. Suppose a biopsy of a patient’s thyroid gland

revealed follicles and follicular epithelial cells that were less than half the normal size. If you took a blood sample from that patient, would you predict the TSH level to be normal, high, or low. Explain your choice.

2. Your patient’s body temperature is 97.1 F, blood pressure and heart rate are below normal. You order a blood test to check for hormone levels. Which hormone(s) is/are of greatest interest to you and why? Based on the symptoms, what predictions do you make about the results of the blood test? Explain.

1QQ # 8 for 9:30 class1. Some tumors of endocrine glands result in

unregulated high levels of hormone secretion. Which would you predict to be more severe: a tumor in the anterior pituitary gland or a tumor in the posterior pituitary gland? Explain your reasoning.

2. Your patient’s body temperature is 97.1 F, blood pressure and heart rate are below normal. You order a blood test to check for hormone levels. Which hormone(s) is/are of greatest interest to you and why? Based on the symptoms, what predictions do you make about the results of the blood test? Explain.

Tropic hormones control the function

Trophic hormones promote survival and growth of targets

Releasing Hormone

Release-inhibiting Hormone

Hypothalamo-hypophyseal portal system

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A

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P

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PPPP

S 1

Tropic hormones control the function

Trophic hormones promote survival and growth of targetsReleasing Hormone Release Inhibiting Hormone

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S 2

Endocrine disorders•Hypersecretion

– Primary– Secondary

•Hyposecretion– Primary– Secondary

CRH

ACTH

Cortisol

hypothalamus

Anterior pituitary

Adrenal Cortex

S 3

Who Cares?

• Symptoms of hypothyroidism

• Levels of TSH and TH?

• Explain enlarged thyroid gland

• Cause: Inadequate dietary intake of iodine

• Treatment?

EndemicGoiter

TRH

TSH

T3 & T4

Goiter

Elevates basal metabolic rate,potentiates response to EPI

If hypothyroid during pregnancy…cretinism = congenital hypothyroidism

S 4

Who else Cares?

Aunt Dot S 5

T3 and T4 from Thyroid gland

TSH from Ant. Pit.

TRH from Hypothal.

⇧Metabolic rate

⇧Temperature⇧sensitivity to EPI (up-regulation of adrenergic receptors)

⇧Heart rate and ⇧Blood Pressure

⇧Lipolysis and fuel mobilization Weight loss

The cause: Abnormal Immunoglobulins in patient activate TSH receptors on Thyroid cells

⇩

⇩

Grave’s Disease

S 6

Blood test:TSH levels lowTH levels high

Grave’s Disease

Treatment:Radioactive IodineMechanism:……..

S 7

⇧Cortisol secretion from Adrenal Cortex

Mobilize fuel from muscle & adipose tissueSuppress non-essential functions (reproduction & growth)Suppress inflammatory &immune responsesPotentiates response to EPI (vascular smooth muscle)

ACTH from Ant. Pit

CRH from Hypothalamus

Physical traumaProlonged exposure to coldProlonged intense exerciseInfectionSleep deprivationPainFrightEmotional distress

Vasopressin

Cytokines fromimmune cells

Excess Cortisol from 1) adrenal cortex tumor (primary) or 2) hypersecretion of ACTH from anterior pituitary (secondary)

Cushing’s Syndrome

Basal levels of CortisolRequired for normal sensitivity to EPI; symptoms of excess cortisol are…..

Clinical example: treatment of chronic inflammation (e.g. arthritis) can lead to Cushing’s Syndrome!

S 8

Applied Physiology: MenopauseWidmaier text p. 694

• Onset ~ age 50• Irregular menstrual cycles• Breasts and genital organs gradually atrophy• Decrease in bone mass & strength

(osteoporosis) (bone resorption greater than bone deposition)

• Hot flashes…sweating, etiology unknown• Increased incidence of coronary artery disease

S 9

Menopause, continued.

• Caused by ovarian failure….loss of estrogen• Estrogen has protective function for

cardiovascular system and sustains bone• Diagnosis

– Test estrogen levels– Test FSH levels….interpretation if high?

• Treatment– Hormone replacement therapy– Risk of HRT: increased incidence of breast cancer &

uterine endometrial cancer– Advantages: alleviates symptoms, restores

cardiovascular protection, sustains bone density

S 10