Endocrine System Flashcards
How are most hormones regulated? Positive or negative feedback loop?
Negative feedback loop
The interactions within the endocrine system constitute the ____________ a major part of the neuroendocrine system that controls reactions to stress and regulates many body processes.
hypothalamic-pituitary axis
The endocrine system helps regulate: (7)
Chemical composition and volume of interstitial fluid
Metabolism and energy balance
Biological clock or circadian rhythms
Contraction of smooth and cardiac muscle fibers
Glandular secretions
Some immune system activities
Operations of reproductive system
Does the endocrine system control growth and development?
Yes
Identify:
Thyroid Feedback Loop
The thyroid senses low levels of thyroid hormones ___ and ___ which then responds by releasing what hormone?
T3 and T4
thyrotropin-releasing hormone (TRH)
The TRH (thyroid-releasing hormone) stimulates the pituitary to produce what?
thyroid-stimulating hormone (TSH)
What hormone is released from the hypothalamus?
TRH (thyroid releasing hormone)
What hormone is released from the anterior pituitary gland?
TSH
________ stimulates the thyroid gland to secrete the hormone thyroxine (T4) (inactive form) which is converted to triiodothyronine (T3), which is the active hormone that stimulates metabolism.
TSH
________ is also produced by the hypothalamus, and has an opposite effect on the pituitary production of TSH, decreasing or inhibiting its release.
Somatostatin
The concentration of thyroid hormones (T3 and T4) in the blood regulates the pituitary release of TSH. True or false?
true
When T3 and T4 concentrations are low, the production of TSH is ______ and vice-versa.
increased
Note: This is known as a negative feedback loop.
T4 and T3 (controlled by TSH) levels peak in the early morning. True or false?
false
Diurnal peaks in late evening.
What factors influence secreted amounts of T3 and T4? (6)
Gender
Pregnancy
Gonadal- and adrenal cortical-increased steroids (increase)
Exposure to cold (increase)
Nutritional state
Chemicals (dopamine, catecholamines)
What are the functions of T3 and T4? (9)
Regulate protein, fat, and carbohydrate catabolism in cells
Regulates metabolic rate and body heat production
Insulin antagonist
Maintains growth hormone secretion, skeletal maturation
Affects CNS development
Maintains cardiac rate, force, and output
Affects respiratory rate and oxygen utilization
Affects RBC production
Enhances cholesterol excretion in the bile
What type of thyroid condition results in a goiter?
Hyperthyroidism
What type of thyroid condition results in exophthalmos?
Hyperthyroidism
What are the symptoms of hyperthyroidism? (10)
Nervousness or anxiety
Increased sweating
Heat intolerance
Palpitations
Dyspnea
Fatigue and weakness
Weight loss or gain
Increased appetite
Hyperdefication or loose stools
Menstrual irregularity
What are the signs and symptoms of hyperthyroidism? (5)
Thyroid enlargement (goiter)
Tachycardia
Atrial fibrillation
Hyperkinesis (state of overactive restlessness)
Eye signs (exophthalmos)
For hyperthyroidism, we would expect the following increase/decrease in labs:
_________ T3 and T4
________ free thyroxine or T4
___________ TSH
elevated T3 and T4
elevated free thyroxine or T4
decreased TSH
What other labs could you expect for a pt with hyperthyroidism? (5)
Hypercalcemia
Increased alkaline phosphatase
Anemia
Decreased granulocytes
Increased erythrocyte sedimentation rate
What is the treatment for hyperthyroidism? (4)
Thioamides
Iodine
Beta-adrenergic blockade
Thyroid surgery
What are preoperative considerations for pts with hyperthyroidism? (2)
Airway exam is important, especially if a goiter is present.
Ptoptosis will require diligent eye protection.
In an emergency surgery situation, what drugs will we need to have available for a pt with hyperthyroidism? (4)
Propythiouracil (PTU)
Propanolol
Potassium iodide
Corticosteroids
What are the symptoms of hypothyroidism? (10)
Cold intolerance
Dyspnea
Anorexia
Constipation
Decreased libido
Menorrhagia, amenorrhea
Oliguria
Arthalgias, myalgias, muscle stiffness and cramps
Dryness
Fatigue
What are the signs of hypothyroidism? (5)
Weight gain (or loss)
Bradycardia
Diastolic hypertension
Cardiac rub or soft heart tones causes by pericardial effusion
Ileus
For hypothyroidism, we would expect the following increase/decrease in labs:
_____ Free T4
________ TSH in primary hypothyroidism
_______ or normal TSH in pituitary insufficiency
Decreased free T4
Increased TSH
Decreased or normal TSH