Endocrine System Flashcards
Glands
Secrete hormones
Hormones
Signaling molecules / messengers secreted directly into the bloodstream to travel distant target tissues inducing a change in gene expression or cellular functioning
Peptide Hormones
- Made up of amino acids (peptides and proteins)
- Transported to the golgi apparatus for modifications that activate the hormone and are released by exocytosis to the correct location to bind to extracellular receptor
First Messenger
Peptide Hormones:
Hormone binds to receptor and triggers the second messenger (second signal)
- IP3
- Ca
- cAMP
Signaling Cascade
Peptide Hormones:
Overall effect and a possibility of each step having amplification or increasing intensity of the signal
Steroid Hormones
- Derived from cholesterol
- Nonpolar molecules allow movement across the cell membrane - receptors are usual intracellular or intranuclear
- Bind to DNA to alter gene transcription (alter mRNA and protein amounts)
- Slower Effets but Last Longer
- Carried by protein (not water soluble)
Amino Acid Derived Hormones
Derived from 1-2 amino acids with a few additional modifications (less predictable hormones)
Similar to Peptide Hormones:
- Epinephrine
- Norepinephrine
Similar to Steroid Hormones:
- T3
- T4
Catecholamines
- Bind to G-protein coupled receptors
- Fast onset
- Short lived
- Similar to Peptides
Includes Epinephrine, norepinephrine and dopamine
Direct Hormones
Secreted then act directly on the target tissue
Tropic Hormones
Require and intermediary to act
Testosterone
- Source: Testes and Adrenal Cortex
- Steroid Hormone
- in response to Gonadotropins LH / FSH ; develops and maintains male reproductive system and secondary male characteristics like muscle growth, voice deepening and hair growth
Estrogen
- Source: Ovary and Placenta
- Steroid Hormone
- Develops and maintains female reproductive system in response to Gonadotropins and causes secondary female characteristics like hair / breast growth and fat distribution
Progesterone
- Source : Ovary and Placenta
- Steroid Hormone
- Promotes maintenance of the endometrium
Melatonin
- Source: Pineal gland located deep within the brain
- Peptide Hormone
- Involved in circadian rhythms and promote feelings of sleepiness
Erythropoietin
- Source: Kidney
- Peptide Hormone
- Stimulates bone marrow to produce erythrocytes (RBCs) in response to low O2 levels
Atrial Natriuretic Peptide (ANP)
- Source: Heart (atrial)
- Peptide Hormone
- Helps regulate salt and water balance; promotes excretion of Na+ thereby increasing urine volume
Thymosin
- Source: Thymus (behind sternum)
- Peptide Hormone
- Stimulate T-Cell Development and differentiation
Hypothalamus
Bridge between the nervous system and endocrine system by regulating the pituitary gland through tropic hormones and is capable of having organism wide effects
- Regulated by a negative feedback system
Hypophyseal Portal System
Blood vessel that directly connects the hypothalamus with the anterior pituitary and stimulates the release of other hormones
Follicle Stimulating Hormone (FSH)
- Triggered by Hypothalamic release of Gonadotropin Releasing hormone (GnRH)
- Source: Anterior Pituitary
- Peptide / Tropic Hormone
- Stimulates follicle maturation in females and spermatogenesis in males
Luteinizing Hormone (LH)
- Triggered by Hypothalamic release of Gonadotropin Releasing hormone (GnRH)
- Source: Anterior Pituitary
- Peptide/ Tropic Hormone
- Stimulates ovulation in females and testosterone synthesis in males
Gonadotropin Releasing hormone (GnRH)
- Source: Hypothalamus
- Stimulates release of FSH and LH
Adrenocorticotropic Hormone (ACTH)
- Triggered by Hypothalamic release of Corticotropin Releasing Hormone (CRF)
- Source: Anterior Pituitary
- Peptide / Tropic Hormone
- Stimulate the adrenal cortex to synthesize and secrete glucocorticoids
Thyroid Stimulating Hormone (TSH)
- Triggered by Hypothalamic release of Thyroid Releasing Hormone (TRH)
- Source: Anterior Pituitary
- Peptide /Tropic Hormone
- Stimulates thyroid to produce thyroid products (hormones)
Corticotropin Releasing Hormone (CRF)
- Source: Hypothalamus
- Triggers release of Adrenocorticotropic Hormone (ACTH)
Thyroid Releasing Hormone (TRH)
- Source: Hypothalamus
- Triggers release of Thyroid Stimulating Hormone (TSH)
Prolactin
- Triggered by Hypothalamic release of Prolactin Inhibiting Factor (PIF) or Dopamine
- Source: Anterior Pituitary
- Peptide / Direct Hormone
- Stimulates milk production in the mammary glands; Removal of Estrogen and Progesterone result in lactation
Endorphins
- Source: Anterior Pituitary
- Peptide / Direct Hormone
- Decrease pain perception / sensation and can promote Euphoria
Growth Hormone (GH)
- Triggered by Hypothalamic release of Growth Hormone Releasing Hormone (GHRH)
- Source : Anterior Pituitary
- Peptide /Direct Hormone
- Stimulates bone / muscle growth; Prevents glucose re-uptake and stimulates breakdown of fatty acids increasing overall glucose level
Growth Hormone Releasing Hormone (GHRH)
- Source: Hypothalamus
- Triggers release of Growth Hormone (GH)
Prolactin Inhibiting Factor (PIF)
- Source: Hypothalamus
- Triggers release of Prolactin
Gigantism
Excess of Growth Hormone (GH) released before closure of epiphyseal plates
Dwarfism
Deficit of Growth Hormone (GH)
Acromegaly
Excess Growth Hormone in adults; enlarging smaller bones like those found in the hands, feet and head
Posterior Pituitary
Neurons are connected from the hypothalamus to the posterior pituitary (“Master Gland”)
Antidiuretic Hormone (ADH) or Vasopressin
- Source: Hypothalamus
- Released by : Posterior Pituitary
- Peptide Hormone
- Stimulates water reabsorption in kidneys by increasing permeability of collecting duct to water
- Greater reabsorption from filtrate and greater retention of water increase blood volume and pressure
Oxytocin
- Source Hypothalamus
- Released by : Posterior Pituitary
- Stimulates uterine contractions during labor and smooth muscle contractions in breast to promote lactation
- Involved in bonding behavior
Positive Feedback Loop
Identified by the theme of “spiraling forward” and have a definitive end point
Ex: Contractions - oxytocin promotes stronger contractions and more of them ending in birth
Thyroid
Controlled by thyroid stimulating hormone which sets basal metabolic rate and calcium homeostasis
Triiodothyronine (T3)
Tyrosine with three iodine
- Source: Thyroid Follicular Cells
- Amino Acid Derivative Hormone
- Stimulate metabolic activity
Thyroxine (T4)
Tyrosine with four iodine
- Source: Thyroid Follicular Cells
- Amino Acid Derivative Hormone
- Stimulate metabolic activity
Calcitonin
- Source: Thyroid parafollicular cells (C-cells)
- Peptide Hormone
- Decrease blood [Ca2+]; Ca2+ is excreted from kidneys and increase Ca2+ storage in bones
Parathyroid Hormone (PTH)
- Source: Parathyroids
- Peptide Hormone
- Increase blood [Ca2+] and [Phosphate] by reducing reabsorption in kidneys and reabsorbing them from bone
- Activates Vitamin D needed for absorption of Ca2+ and phosphate in the gut
Hypothyroidism
Deficiency of iodine or inflammation of thyroid in which thyroid hormones are insufficient or not secreted at all
Cretinism
Deficiency of thyroid hormone at birth (mental retardation and delay)
Hyperthyroidism
Excess of thyroid hormone
Parathyroid
4 small pea sized structures that sit on the posterior surface of the thyroid
Calcium
- Important in bone strength
- Regulates muscle contraction
- Cofactor allowing for clotting of blood
- Role in cell movement, exocytosis and neurotransmitter release
Glucocorticoids
Cortisol + Cortisone
- Source: Adrenal Cortex
- CorticoSteroid Hormone
- Increase [blood glucose] through gluconeogenesis
- Decrease protein synthesis; anti-inflammatory
- Decrease immunological Responses
Mineralocorticoids
Aldosterone
- Source: Adrenal Cortex
- CorticoSteroid Hormone
- Increase water reabsorption in kidneys by increasing Na+ reabsorption
- Promote K+ and H+ ion excretion
Cortical Sex Hormones
- Source: Adrenal Cortex
- CorticoSteroid Hormone
- Aids in producing androgens and estrogen
Epinephrine and Norepinephrine
- Source: Adrenal Medulla
- Amino Acid Derivative Hormone
- Secreted directly into circulatory system: Fight or Flight hormones in sympathetic nervous system
- Increase blood [glucose]
- Increase heart rate
- Dilate Bronchi
- Alter blood flow
Adrenal Medulla
On top of kidneys; consisting of Cortex and Medulla
Cortisol
Stress hormone; Increases blood sugar (ready source of fuel)
Pancrease
Both Exocrine and Endocrine Functions
Islets of Langerhans
Small groups of hormone producing cells
- Alpha cells
- Beta cells
- Delta cels
Alpha Pancreatic Cells
Type of Islets of Langerhans Cells:
- Produce glucagon
Beta Pancreatic Cells
Type of Islets of Langerhans Cells:
- Produce Insulin
Delta Pancreatic Cells
Type of Islets of Langerhans Cells:
- Produce Somatostatin
Glucagon
- Source: Pancreas Alpha Cells
- Peptide Hormone
- Stimulates glycogen breakdown (glycogenolysis)
- Increases blood [glucose] and stimulates degradation of fats and proteins
- When fasting
Insulin
- Source: Pancreas Beta Cells
- Peptide Hormone
- Lowers blood [glucose]
- Increases anabolic processes like protein and fat synthesis
- When glucose is high
Somatostatin
- Source: Pancreas Delta Cells
- Peptide Hormone
- Suppresses secretion of glucagon, insulin and growth hormone (GH)
- When there is high [glucose] and [amino acid]
Hypoglycemia
Excess insulin characterized by low blood [glucose]
Diabetes Mellitus
Underproduction, insufficient secretion or insensitivity to insulin
Hyperglycemia
Excess Glucose in blood (too little insulin)
Polyuria
Increase frequency of urination
Polydipsia
Increased thirst
Diabetes Mellitus Type 1
Autoimmune destruction of beta cells in pancreas; producing little to no insulin as a result
Diabetes Mellitus Type 2
Result of receptor-level resistance to the effects of insulin
