Endocrine Flashcards
How does the endocrine system send messages?
Hormones sent to target cells
How does the rate of effect of the endocrine system compare to the nervous system?
It is much slower and often has a longer affect
Where is the pineal gland?
Epithalamus region of brain
What cells make up the pineal gland and what special function do they have?
Pinealocytes
Produce and release melatonin
What is the function of the pineal gland?
Sleep-wake cycle and circadian rhythm
Produces melatonin
Influences the release of LH and FSH
What influences melatonin production and release?
Influenced by hypothalamus in response to light information
In low level light the pineal gland will secrete more melatonin = sleep
Where is the pituitary gland located?
At the base of the brain within sella turcica
What is the general function of the pituitary gland?
Controls other endocrine glands by releasing hormones targeting them
How many lobes make up the pituitary gland?
Two: posterior and anterior
What 5 hormones are secreted by the anterior pituitary lobe?
Growth hormone (growth and development)
Prolactin (breast milk and reproduction)
Adrenocorticotropic hormone (tells adrenal to release cortisol)
Thyroid stimulating hormone (controls thyroid hormone release)
Follicle stimulating hormone + luteinising hormone (gonad function)
What hormones are produced by the posterior pituitary lobe?
Does not produce hormones itself - it stores and releases hormones from hypothalamus
Oxytocin (birth, milk, emotional bond)
Antidiuretic hormone (water balance/BP)
What is the general function of the hypothalamus?
Link the nervous and endocrine system
Regulate autonomic processes
Integrate signals
Produce/release hormones to stimulate anterior pituitary
What 4 hormones are released from the hypothalamus to stimulate the anterior pituitary lobe?
Gonadotropin-releasing hormone (release FSH + LH)
Corticotropin-releasing hormone (release ACTH)
Thyrotropin-releasing hormone (release TSH)
Growth hormone-releasing hormone and growth hormone-inhibiting hormone (GH)
What is the general function of the thyroid gland?
Regulate metabolism
Regulate growth and development
Maintenance of homeostasis
How many lobes make up the thyroid gland?
Two: left and right
Separated by narrow band called isthmus
What cells make up the thyroid gland?
Follicular cells which produce/store hormones
What hormones are produced in the thyroid gland?
Thyroxine (composed of iodine, controlled by pituitary TSH)
Triiodothyronine (composed of iodine, controlled by pituitary TSH)
Calcitonin (regulates blood calcium level by reducing bone break down/kidney excretion)
What is the line of control for thyroid hormones?
Hypothalamus: Thyrotropin-releasing hormone stimulates pituitary gland
Pituitary gland: thyroid-stimulating hormone stimulates thyroid
Thyroid: thyroxine and triiodothyronine released
Where is the parathyroid gland?
4 small glands embedded in thyroid gland
What cells make up the parathyroid gland?
Chief cells = parathyroid hormone
Oxyphil cells
What is the general function of the parathyroid glands?
Regulate phosphate and calcium levels
How does the parathyroid gland regulate calcium levels?
Parathyroid hormone increases calcium levels
Targets bone to release calcium
Targets kidney to reabsorb calcium
Targets intestine to activate vitamin D (increased Ca absorption)
Where is the thymus gland located?
In upper chest between lung and sternum
What is the general function of the thymus gland?
Develop/mature T-lymphocyte cells made in the bone marrow
Secretes thymosin hormone to support T cells
More active in childhood
What is the function of the adrenal cortex?
Produces aldosterone (mineralocorticoid) to regulate electrolyte balance and BP
Targets kidney to increase Na and decrease K
What is the function of the middle adrenal gland layer?
Produce cortisol (glucocorticoid)
Metabolism and stress response
What is the function of the adrenal medulla?
Produce adrenaline + noradrenaline (catecholamine)
Sympathetic nervous system response
What is the line of control of the adrenal glands?
Hypothalamus: corticotropin-releasing hormone stimulates pituitary gland
Pituitary gland: adrenocorticotropic hormone stimulates adrenal gland
Adrenal gland: releases cortisol
What is the difference between an endocrine and exocrine gland?
Endocrine secretes into blood stream
Exocrine secretes elsewhere
What is the general function of the pancreas?
Secretes digestive enzymes into the small intestine
Controls blood sugar levels
How does the pancreas control blood sugar level?
High: beta cells secrete insulin to open gated-glucose-channels to allow cells to uptake glucose and promotes storage as glycogen in the liver
Low: alpha cells secrete glucagon to stimulate liver to release store glycogen into blood
What is the general function of the gonads?
Produce gametes (ova + sperm) and sex hormones
What is the line of control of the gonads?
Hypothalamus: gonadotropic-releasing hormone stimulates pituitary gland
Pituitary: FSH + LH stimulates the gonads
Gonads: estrogen, progesterone and testosterone
What is hyperparathyroidism?
Overactive parathyroid gland
High PTH and Ca
SX: tired, weak, kidney stone, polyuria, bone pain
What is hypoparathyroidism?
Under active parathyroid gland
Low PTH
SX: cramps, tired, moody, dry skin, tingling extremities
What is hypothyroidism?
Under active thyroid
Low TH
SX: fatigue, cold, weight gain, depression, dry skin
What is hyperparathyroidism?
Overactive thyroid gland
High TH
SX: weight loss, tachycardia, heat intolerance, sweating, trembling
What is Cushing syndrome?
Overactive adrenal gland
High cortisol
SX: weight gain, thin skin, high BP, weak, moody
What is Addison disease?
Under active adrenal gland
Low cortisol
SX: weight loss, fatigue, low BP, weak, darkened skin, salt craving
What is hypopituitarism?
Reduced pituitary hormones
SX: tired, reduced sex drive, reduced fertility, weight change
What is diabetes insipidus?
High or altered ADH function
SX: excessive thirst and urination, electrolyte imbalance, dehydration
What is adrenaline?
A hormone and NT produced in the adrenal medulla for a sympathetic response
What is vasopressin?
Antidiuretic hormone
Made in the hypothalamus + stored in the pituitary gland
Regulates water balance by targeting the kidneys to reabsorb more/less water
What is Type 1 DM?
Autoimmune disorder where beta cells of pancreas are attacked resulting in low insulin levels
SX: polyuria, polydipsia, weight loss, weak, hungry, blurred vision, moody, recurrent infections
What is diabetic ketoacidosis?
Low or insufficient insulin levels leads to body breaking down fat for energy with the byproduct being ketones. Ketones are acidic so cause metabolic acidosis
TX: insulin, fluid and electrolytes
What is Type 2 DM?
Insufficient levels of insulin produced and/or cells become resistant to insulin
Caused by lifestyle factors
What is gestational diabetes?
Hormones interfere with insulin activity and the pancreas isn’t producing enough insulin to overcome this (because insulin resistance is normal in pregnancy to support BGL of baby and mother)
COMP: big baby, baby low BGL postnatal, high risk pre-term birth, high BP, preeclampsia, risk of mother developing T2DM later
What is normal blood sugar levels?
4-8 mmol/L
How does the endocrine system differ in paediatrics?
Reduced glycogen stores (underdeveloped liver)
High glucose demand due to metabolic activity
Hormones important for development
How does the geriatric endocrine system differ?
Reduced pituitary function
Less growth hormones
Reduced appetite = malnourished
Fertility lessened
Reduced insulin function marginally increases BGL
Reduced thyroid function = reduced metabolic activity
What is hypoglycaemia?
Blood sugar level < 4 mmol/L
What are the SX of hypoglycaemia?
Shaking
Sweating
Palpitations or tachycardia
Weak/fatigue
Hunger/craving
Irritable/anxious
Dizzy
Confused/reduced concentration
Blurred vision
Headache
Tingles or numbness
Severe: ALOC, disorientated, seizure, dysphasia, one-sided weakness, coma, death
What are the treatment options for hypoglycaemia?
Glucose oral paste
IV dextrose
IM glucagon
