Endocrine: Thyroid, Parathyroid, Adrenal Glands Flashcards
How many lobes does the thyroid gland have?
2 - on either side of larynx
Narrow band that may connect the lobes of the thyroid depending on species?
Isthmus
True or False: Thyroid is composed of tens of thousands of tiny follicles
True
What two hormones that are secreted in the thyroid?
Thyroid Hormone
Calcitonin
What are the two hormones that make up thyroid hormone?
T4 = tetraiodothyronine = thyroxine
T3 = triiodonthyronine
Thyroid hormone: Prohormone, a circulating reservoir
T4
Thyroid hormone: The active hormone
T3
Where do the names of the thyroid hormones come from?
Number of iodine atoms that each molecule of hormone contains
Ie. T4 has 4 iodine atoms per molecule
Thyroid Hormone’s ____________ effect helps heat the body
calorigenic
What does the calorigenic effect regulate?
Metabolic rate of all the body’s cells
(rate at which they burn nutrients to produce energy)
The effect of TH on metabolic rate allows animals to what?
Generate heat and maintain a constant internal body temperature
How does TH affect metabolism of proteins?
Encourages anabolism (synthesis) of proteins, depending on if animals diet contains adequate energy sources
How does TH affect metabolism of carbs?
Hyperglycemic effect; maintains homeostasis of blood glucose level
How does TH affect metabolism of lipids?
Encourages catabolism of lipids
How does TH effect young, growing animals?
Necessary for normal growth and development
Influences development and maturation of CNS and muscles/bones
Where is calcitonin produced?
By C cells located between thyroid follicles
Calcitonin helps maintain _______ _______ levels
blood calcium
What are the 2 hormones that maintain homeostasis of blood calcium levels
Calcitonin
Parathyroid Hormone
What does calcitonin help prevent?
Hypercalcemia by encouraging excess calcium to be deposited in bones
What is another name for Parathyroid Hormone (PTH)
Parathormone
Where is the parathyroid glands located?
In, On, or near the thyroid glands.
What does PTH help prevent?
Hypocalcemia
Where are adrenal glands located?
Near cranial ends of kidneys, triangular shaped, not actually attached
True or False: Adrenal glands are a single structure
False - 2 glands, one wrapped around the other (like chocolate wrapped around a peanut)
What are the two glands that make up the adrenal glands?
Adrenal Cortex (outer)
Adrenal Medulla (inner)
How is the adrenal cortex developed?
From glandular tissue
What are the 3 main categories of hormones that the adrenal cortex produce?
Glucocorticoids
Mineralcorticoids
Sex hormones
What are the 3 glucocorticoids?
Cortisone
Cortisol
Corticosterone
What is the general effect of glucocorticoids?
Hyperglycemic effect - cause blood glucose to rise
What are two other things that glucocorticoids help with?
Maintaining blood pressure
Helping the body resist the effects of stress
What is the principal mineralcorticoid hormone?
Aldosterone
What is the purpose of mineralcorticoids?
Regulate levels of electrolytes
What are the 2 sex hormones?
Androgens (male)
Estrogens (female)
True or False: There is a large amount of sex hormones produced in the adrenal cortex
False - very small amounts and their effects are usually minimal
True or False: The adrenal medulla resembles nervous tissue
True
What are the two hormones produced by the medulla?
Epinephrine
Norepinephrine
What is the medulla hormone secretion controlled by?
Sympathetic portion of the autonomic nervous system - threat-control system
What response is triggered when animal feels threatened?
Fight or Flight response
True or False: High levels of glucocorticoids due to constant stress lead to a weak immune system
True
Deficiency of thyroid hormone
Hypothyroidism
What are the clinical signs of hypothyroidism?
Alopecia
Dry Skin
Lethargy
Reluctance to exercise
Weight gain without appetite increase
Excess of Thyroid hormone
Hyperthyroidism
True or False: Hyperthyroidism is more common in dogs than cats?
False - more common in cats
What are the clinical signs of hyperthyroidism?
Nervousness
Excitability
Weight Loss
Increased Appetite
Tachycardia
Vomiting
Diarrhea
PU/PD
What species is hypothyroidism more common in?
Dogs
Disease also referred to as hyperadrenocorticism
Cushing’s diease
What are the clinical signs of cushing’s disease?
PU/PD
Polyphagia (increased appetite)
Hair Loss
Muscle Wasting
Slow wound healing
Disease also referred to as hypoadrenocorticism
Addison’s disease
What are the clinical signs of addison’s disease?
Weakness
Lethargy
Vomitting
Diarrhea
Lead to circulatory problems and kidney failure
Condition that can occur in cats and dogs from Hypocalcemia?
Eclampsia
What is eclampsia?
Causes muscle tremors and spasms that can progress to full-blown seizures if left untreated
