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61 Cards in this Set
- Front
- Back
General Overview of Endocrine System
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produces hormones
maintains homeostasis and coordinates growth |
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How does Endocrine Hormonal Stimulation compare to Neuronal Stimulation?
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slower, more prolonged response
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Mechanisms for Hormone Control:
Endocrine |
hormone released into circulation to transport to cell
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Mechanisms for Hormone Control:
Paracrine |
released into CT to affect neighboring cells
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Mechanisms for Hormone Control:
Autocrine |
Hormone acts on cell it is released from
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Classes of Hormones:
Steroids |
cholesterol derived
secreted from Testes, Ovaries, and Adrenal Cortex requires carrier protein |
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Classes of Hormones:
Small peptides, proteins and glycoproteins |
produced in: hypothalamus, pituitary, thyroid, parathyroid, pancreas
dissolve in blood stream, no carrier protein needed |
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Classes of Hormones:
Amino Acid Analogues |
Catecholamines and Thyroid Hormones
produced by neurons and adrenal medulla and thyroid Catacholamines: no carrier protein Thyroid Hormones: carrier protein |
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What are examples of Catecholamines?
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Epinephrine and Norepinephrine
no carrier protein required |
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Receptors for Hormones:
Cell Surface Receptors |
interact w/ peptide hormones or Catecholamines
binding causes activation of mb-associated G proteins 2nd messengers are produced |
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Receptors for Hormones:
Intracellular Receptors (Nuclear) |
utilized by steroids, thyroid hormones (can cross membrane)
3 binding domains found on receptor causes allosteric conformation change directly regulates gene expression |
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What are the 3 binding domains found on Nuclear Intracellular Receptors?
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Hormone-binding domain
DNA-binding domain N-terminal domain |
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Regulation of Hormone Secretion:
Negative Feedback |
response decreases original stimulus
more common |
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Regulation of Hormone Secretion:
Positive Feedback |
response increases original stimulus
less common |
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What does the Pituitary Gland work with to regulate hormone levels of the endocrine system?
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Hypothalamus
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Components of Pituitary Gland:
Anterior Lobe |
glandular epithelial tissue
derived from ectoderm of oropharynx toward brain (Rathke's Pouch) Pars Distalis, intermedia, and tuberalis |
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Components of Pituitary Gland:
Posterior Lobe |
Neural secretion tissue
derived from downgrowth or neuroectoderm of 3rd ventricle Pars Nervosa, Infundibulum |
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Blood Supply of the Pituitary Gland
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superior hypophyseal arteries
inferior hypophyseal arteries Anterior lobe has NO DIRECT arterial supply |
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what directly regulates Endocrine function of the Pituitary Gland?
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Hypothalamic releasing and inhibitory factors
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Innervation of the Pituitary Gland
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Nerves in Infundibular and Pars Nervosa are components of posterior lobe
Nerves in Anterior Lobe are Postganglionic ANS fibers |
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Tropic Hormones of Anterior lobe of Pituitary
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regulate activity of OTHER endocrine glands
ACTH TSH-Thyroid Stimulating FSH-Follicle Stimulating LH-Luteinizing |
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Non-Tropic Hormones of Anterior lobe of Pituitary
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act directly on non-endocrine target organs
GH Prolactin (PRL) |
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Pars Distalis cells
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Acidophils
Basophils Chromophobes |
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Acidophils:
Somatrotopes |
produce GH
regulated by 2 hormones from Hypothalamus GHRF- Growth hormone stimulating Somatostatin |
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GHRF
Growth Hormone-Releasing Factor |
stimluates GH release
from Hypothalamus |
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Somatostatin
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inhibits GH release
From Hypothalamus |
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Acidophils:
Lactotropes |
produce Prolactin (PRL)
stimulates initiation of lactation becomes Chromophobes after secretion |
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How is secretion of Prolactin from Lactotrophes regulated?
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negative feedback
increased Prolactin increases Dopamine causes decrease in Prolactin secretion |
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What stimulates Secretion of Prolactin?
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TSH from Pars Distalis
VIP |
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Basophils:
What do Corticotropes produce? |
produce precursor of ACTH, called Proopiomelanocortin (POMC)
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What can Proopiomelanocortin (POMC) be turned into?
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ACTH (Corticotropin)
B-Lypotrophic MSH Enkephalin B-endorphin |
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What regulates release of POMC from Corticotropes?
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Corticotrophin-releasing hormone (CRH) from Hypo
also inhibited by high levels of Cortisol |
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Basophils:
Gonadotropes |
produce FSH and LH
regulated by Gonadotropin-releasing hormone (GnRH) |
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Basophils:
Thyrotopes |
Produce TSH
regulated by TRH from Hypo |
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what is the function of TSH?
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increase production of Thyroglobulin and Thyroid Hormones in Thyroid Follicular Cells
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Pars Intermedia
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surrounds small cystic cavities
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Pars Tuberalis
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extends along Infundibulum
cells often contain ACTH, FSH, and LH |
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Pars Nervosa
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NOT endocrine gland
ending point for axons Piuicyte: specialized Glial Cell |
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3 sizes of Neuronal Vesicles in Nerve Endings of Nervosa:
10-30nm |
10-30nm- contain Oxytocin, ADH, ATP, and Neurophysin
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3 sizes of Neuronal Vesicles in Nerve Endings of Nervosa:
30nm |
contain Acteylcholine
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3 sizes of Neuronal Vesicles in Nerve Endings of Nervosa:
50-80nm |
resemble core vesicles of adrenal medulla
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ADH Function
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increases BP
Increases permeability of tubule or nephron and collecting ducts ADH release causes increase in Osmolality or decrease in Blood Volume |
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Oxytcin Function
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more potent than ADH
causes contraction of Uterine SM and myoepithelial cells of mammary glands |
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Thyroid Gland General Features
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Bi-lobed
thin CT capsule Stores its secretory product EXTRACELLULARLY |
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Thyroid Follicle Cells
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contains Colloid
apical surface on Colloid, basal surface on Basal Lamina |
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Thyroid Follicular Cells
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produce T3 and T4
lysosomes and endocytotic vesicles resorb colloid |
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Parfollicular Cells
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secrete Calcitonin
regulates Calcium Metabolism |
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Thyroid Hormones:
Calcitonin |
lowers blood Ca2+ levels
regulated directly by Ca2+ fluid levels |
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Thyroid Hormones:
Thyroxine |
T4 and T3
regulate cell and tissue metabolism, heat, body growth and development Regulated by TSH |
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Thyroid Hormones:
Thyroglobulin |
NOT a Hormone
inactive storage form of Thyroid Hormones |
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Formation of T3 and T4
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2 iodinated residues in close proximity undergo oxidative coupling to form Thyroid Hormones
remain stored as colloid within lumen of follicle |
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Resorption of Colloid
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TSH induces follicular cells to uptake Thyroglobulin from colloid
degraded w/ lysosome free T3 and T4 |
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Release of T3 and T4
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cross Basal membrane to lymphatic capillaries
only 5% of circulating cells are active |
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T4-->T3
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T4 only produced by follicular cells
T3 produced by conversion of T4 in kidney, liver, and heart |
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Parathyroid Gland General Features
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Ovoid
Thin CT capsule fat cells increase w/ age |
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Chief Cells of Parathyroid
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secrete Parathyroid Hormone (PTH)
regulate fetal Ca2+ metabolism |
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Oxiphils of Parathyroid
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no Secretion
thought to be Immature Chief Cells |
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Parathyroid Hormone (PTH)
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activates G proteins and acts as a 2nd messenger
increases Calcium level in blood decreases blood Phosphate Level |
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Regulation of PTH Secretion
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lower blood calcium: stimulates secretion
High blood Calcium: inhibits secretion |
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Fxn Parathyroid Hormone (PTH)
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stimulates resorption of bone
regulates conversion of Vitamin D to active form |
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PTH vs. Calcitonin
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PTH: slower, longer lasting
Calcitonin: faster, acute |