Hypothalamic-Pituitary Relationships and Biofeedback Pt. 1 Flashcards
What is the pituitary gland called? What is the anterior pituitary gland called? What is the posterior pituitary gland called?
Pituitary: hypophysis
AP: adenohypophysis (epithelial portion)
PP: neurohypophysis (neural portion)
What is the hypophysial stalk?
Physical connection between the hypothalamus and the pituitary gland
What is usually associated with pituitary tumors?
Visual problems, dizziness
What is found in the posterior pituitary?
Collection of axons and nerve terminals whose cell bodies are located in the hypothalamus, specifically from supraoptic nucleus and paraventricular nucleus
What does the posterior pituitary secrete?
ADH from supraoptic nucleus and oxytocin from periventricular nucleus
These are neuropeptides
What is found in the anterior pituitary?
Collection of endocrine cells derived from primitive foregut
How is the anterior pituitary connected to the hypothalamus?
Connected by hypothalamic-hypophysial portal blood vessels
What hormones are secreted by the anterior pituitary?
ACTH, TSH, FSH, LH, GH, prolactin
These hormones can be directly delivered to the anterior pituitary in high concentrations, but do not appear in high concentrations in systemic circulation.
Hypothalamic-releasing hormones or release-inhibiting hormones
The connections between the hypothalamus and the posterior pituitary are _______. The connections between the hypothalamus and the anterior pituitary are both ______ and _______.
Neural; neural and endocrine
What makes up the ACTH family in the anterior pituitary?
Corticotrophs, which secrete ACTH
What makes up the TSH, FSH, LH family in the anterior pituitary?
Thyrotrophs, which secrete TSH and gonadotrophs, which secrete FSH and LH
What makes up the GH and prolactin family in the anterior pituitary?
Somatotrophs, which secrete GH and lactotrophs, which secrete prolactin
What is primary endocrine disorder?
Low or high levels of hormones due to defect in the peripheral endocrine gland
What is secondary endocrine disorder?
Low or high levels of hormones due to defect in the pituitary gland
What is tertiary endocrine disorder?
Low or high levels of hormones due to defect in the hypothalamus
What are the anterior pituitary gland axes?
Hypothalamic-pituitary-gonad Hypothalamic-pituitary-liver Hypothalamic-pituitary-prolactin Hypothalamic-pituitary-thyroid Hypothalamic-pituitary-adrenal
How are FSH and LH regulated?
Regulated by hypothalamic GnRH release (pulsatile); extreme energy deficits (anorexia nervosa or starvation), extreme exercise, and depression can inhibit GnRH function
What is the function of FSH and LH?
Promotes estrogen and progesterone secretion in females; promotes testosterone production in males
What does a normal menstrual cycle depend on?
LH and FSH
What is acromegaly?
Characterized by excessive growth of soft tissue, cartilage, and bone in the face, hands, and feet; develops very gradually and may not be recognized until has been present for many years; caused by prolonged and excessive secretion of GH in adult life
What does GH target? What is the GH receptor linked to? How is GH regulated?
Targets liver and bone; GH receptor linked to JAK-STAT signaling; inhibited by somatostatin and IGF-1 signaling as part of negative feedback
What stimulates GH?
Fasting/hunger/starvation, hypoglycemia, hormones of puberty, exercise, sleep, stress
What are the direct actions of GH?
Growth, cell reproduction, metabolism (increase glyogen and fat breakdown for energy and increased protein synthesis)
What is hypertrophy? Give an example
Increase in size/volume of cells; example is increased bone thickness
What is hyperplasia? Give an example
Increase number of cells or proliferation rate via mitosis; example is increase in bone length
What are the indirect actions of GH?
Majority of growth is indirect method; tropic function; signals to liver to produce IGF (insulin-like growth factors); targets almost every cell in the body; stimulates hypertrophy and hyperplasia
What are the somatostatins? Where are they located?
Growth hormone release hormone (GHRH) and growth hormone inhibiting hormone (GHIH); hypothalamus
What are the somatotropins? Where are they located?
Growth hormone (GH); anterior pituitary
What are the somatomedin C’s? Where are they located?
Insulin-like growth factor (IGF) and insulin-like growth factor 1 (IGF-1); liver
What is gigantism?
Excess in GH before closure of bone epiphyses due to IGF-1 stimulated long bone growth; before puberty
What is acromegaly?
Excess in GH after closure of bone epiphyses due to promotion of growth of deep organs and cartilaginous tissue; after puberty
Describe prolactin (PRL)
Synthesized by lactotropes; secretion begins to increase around 5th week of pregnancy; secretion is pulsatile; it is under tonic inhibition by hypothalamic dopamine; primary action is to stimulate and maintain lactation; suppresses GnRH (inhibits FSH/LH); decreases reproductive function and suppresses sexual drive
What are stimulating factors for PRL secretion?
Pregnancy (estrogen), breast-feeding (suckling), sleep, stress, TRH
What are inhibitory factors for PRL secretion?
Dopamine, dopamine agonists, somatostatins, prolactin via negative feedback
Describe pituitary adenomas
Hormone-producing pituitary adenomas that release an active hormone in excessive amounts into the bloodstream; patients usually experience symptoms related to the hormone action on the body
What are some examples of pituitary adenomas and what is their percentage of occurrence?
Prolactinoma (60%), acromegaly/gigantism (20%), and Cushing’s disease (10%)
What are causes of hypopituitarism?
1) Brain damage - traumatic brain injury, subarachnoid hemorrhage, irradiation, stroke
2) Pituitary tumors
3) Non-pituitary tumors - craniopharyngioma (most common tumor affecting the HP axis in children)
4) Infections - meningitis, encephalitis, hypophysitis
5) Infarction - sheehan syndrome (pituitary in pregnancy is enlarged and more vulnerable to infarction)
6) Autoimmune disorders
7) Pituitary hypoplasia or aplasia
8) Genetic disorders
What are the actions of oxytocin?
Milk ejection and uterine contractions
What does milk letdown cause?
Stimulates contraction of myoepithelial cells lining milk ducts
What is pitocin?
Induction of labor
