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MCAT Bio. Ch. 5

Endocrine Signaling Involves The Secretion Of Hormones Directly: Into the bloodstream.
Peptide Hormones Are Composed Of: Amino acids and are derived from larger precursors that are cleaved during posttranslational modification
Peptide Hormones Are Polar And Cannot Pass Through: The plasma membrane
Hormones Bind To Extracellular Receptors Where: They trigger the transmission of a second messenger
Each Step Of The Signaling Cascade For Peptide Hormones Can Demonstrate: Amplification of the signal
Peptide Hormones Usually Have Rapid Onset But: Are short-lived
Peptide Hormones Travel Freely in The Bloodstream And: Do not require a special carrier
Steroid Hormones Are Derived From: Cholesterol
Steroid Hormones Are Minimally Polar And Can Pass Through: The plasma membrane
Steroid Hormones Bind To Intracellular Or Intranuclear Receptors Where: The promote conformational change and bind to DNA which affects the transcription of a particular gene
Steroid Hormones Usually Have Slow Onset But: Are long-lived
Steroid Hormones Cannot Dissolve In The Bloodstream And Must Be Carried By: Specific proteins
Amino Acid-Derivative Hormones Are: Modified amino acids. Their chemistry shares some features with peptide hormones and some features with steroid hormones. Different amino acid-derivative hormones share different features with other hormone classes.
Common Examples Of Amino Acid-Derivative Hormones Include: Epinephrine, norepinephrine, triiodothyronine, and thyroxine
Direct Hormones Have Major Effects In: Non-endocrine tissues
Tropic Hormones Have Major Effects In: Other endocrine tissues
Hypothalamus Bridge between the nervous and endocrine systems
Release Of Hormones From The Hypothalamus Is Mediated By A Number Of Factors Including: Projections from other parts of the brain, chemo- and baroreceptors in the blood vessels and negative feedback from other hormones.
Negative Feedback Final hormone or product of a pathway inhibits hormones or enzymes earlier in the pathway to maintain homeostasis
Hypothalamus Stimulates The Anterior Pituitary Gland Through: Paracrine release of hormones into the hypophyseal portal system which directly connects the two organs
Gonadotropin-releasing Hormone (GnRH): Promotes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
Growth Hormone-releasing Hormone (GHRH): Promotes the release of growth hormone
Thyroid-releasing Hormone (TRH): Promotes the release of thyroid stimulating hormone (TSH)
Corticotropin-releasing Factor (CRF): Promotes the release of adrenocorticotropic hormone (ACTH)
Prolactin-inhibiting Factor (PIF or dopamine): Inhibits the release of prolactin
Anterior Pituitary Releases Hormones In Response To Stimulation From: Hypothalamus
Follicle-stimulating Hormone (FSH): Promotes the development of ovarian follicles in females and spermatogenesis in males
Luteinizing Hormone (LH): Promotes ovulation in females and testosterone production in males
Adrenocorticotropic Hormone (ACTH): Promotes synthesis and release of glucocorticoids from the adrenal cortex
Thyroid-Stimulating Hormone (TSH): Promotes synthesis and release of triiodothyronine and thyroxine from the thyroid
Prolactin: Promotes milk production
Endorphins: Decrease perception of pain and can cause euphoria
Growth Hormone (GH): Promotes growth of bone and muscle and shunts glucose to these tissues. It raises blood glucose concentrations.
Posterior Pituitary: Releases two hormones produced in the hypothalamus
Antidiuretic Hormone (ADH or Vasopressin) Is Secreted In Response To: Low blood volume or increased blood osmolarity and increases reabsorption of water in the collecting duct of the nephron, which increases blood volume and decreasing blood osmolarity
Oxytocin: Is secreted during childbirth and promotes uterine contractions. This also promotes milk ejection and may be involved in bonding behavior. It also has a positive feedback loop.
Thyroid Is Located: At the base of the neck in front of the trachae, and produces three key hormones
Triiodothyronine (T3) and Thyroxine (T4) Are Produced By: Follicular cells and contain iodine. They increase basal metabolic rate and alter the utilization of glucose and fatty acids. They are required for proper neurological and physical development in children.
Calcitonin Is Produced By: Parafollicular (C) cells. It decreases plasma calcium concentration by promoting calcium excretion in the kidneys, decreasing calcium absorption in the gut and promotes calcium storage in bone.
Parathyroid Glands Release: Parathyroid hormone (PTH) which increases blood calcium concentration
PTH Decreases Excretion Of: Calcium by the kidneys and increases bone resorption directly to increase blood calcium concentration.
PTH Activates: Vitamin D which is necessary for calcium and phosphate absorption from the gut
PTH Promotes Resorption Of: Phosphate from bone and reduces reabsorption of phosphate in the kidney but Vitamin D promotes absorption of phosphate from the gut. These two effects cancel each other out.
Adrenal Cortex Produces Three Classes Of Steroid Hormones: Glucocorticoids, mineralocorticoids, and cortical sex hormones
Glucocorticoids Such As Cortisol And Cortisone: Increase blood glucose concentration, reduce protein synthesis, inhibit the immune system, and participate in the stress response
Glucocorticoid Release Is Stimulated by: ACTH
Mineralocorticoids Such As Aldosterone Promote: Sodium reabsorption in the distal convoluted tubule and collecting duct thus increasing water reabsorption. Aldosterone also increases potassium and hydrogen ion excretion.
Mineralocorticoids Are Regulated By: The renin-angiotensin-aldosterone system not ACTH
Cortical Sex Hormone Include Androgens (testosterone) and estrogen in both males and females
Adrenal Medulla Is Derived From: The nervous system and secretes catecholamines into the bloodstream
Catecholamines Include: Epinephrine and norepinephrine which are involved in the fight-or-flight (sympathetic) response
Catecholamines Promote: Glycogenolysis, increase the basal metabolic rate, increase heart rate, dilate the bronchi, and alter blood flow
Endocrine Pancreas Produces Hormones That Regulate: Glucose homeostasis
Glucagon Is Produced By: α-cells and raises blood glucose levels by stimulating protein and fat degradation, glycogenolysis, and gluconeogenesis
Insulin Is Produced By: β-cells and lowers blood glucose levels by stimulating uptake by cells and anabolic processes like glycogen, fat, and protein synthesis
Somatostatin Is Produced By: δ-cells and inhibits insulin and glucagon secretion
The Testes Secrete: Testosterone
The Ovaries Secrete: Estrogen and progesterone
The Pineal Gland Releases: Melatonin which helps to regulate circadian rhythms
The Pineal Gland Releases: Melatonin which helps to regulate circadian rhythms
Cells In The Stomach And Intestine Produce Hormones Like: Secretin, gastrin, and cholecystokinin
The Kidneys Secrete: Erythropoietin which stimulates bone marrow to produce erythrocytes (red blood cells) in response to low oxygen levels in blood.
The Atria Of The Heart Secrete: Atrial natriuretic peptide (ANP) which promotes excretion of salt and water in the kidneys in response to stretching of the atria (high blood volume)
The Thymus Secretes: Thymosin which is important for proper T-cell development and differentiation
Created by: SamB91
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