Endocrine System Flashcards
Hormones
Endocrine signaling molecules that run directly into the blood stream, travel long distance to target tissues, where they bing to receptors and induce a change in gene expression or cell function
Peptide hormones
- Composed of amino acids
- polar cannot pass through the plasma membrane
- Bind to extracellular receptors where they affect levels of second messenger (cAMP) and initiates a cascade
Peptide hormones travel method
Dissolves and travels freely WITHOUT carriers
Peptide hormones rapidness of onset and duration of action
Quick onset and short lived
Steroid hormones
- Derived from cholesterol
- mostly non-polar and pass through plasma membrane
- binds to a receptor, induces conformational change and regulates transcription at the level of DNA
Steroid hormones travel method
Binds to a carrier protein
Steroid hormones rapidness of onset and duration of action
Slow and long lived
How are amino acid derivative hormones synthesized?
Made by modifying amino acids, such as the addition of iodine to tyrosine ( in thyroid hormone production)
Direct hormone
Are secreted into the bloodstream and travel to a target tissue, where they have direct effects.
- Major effects in non-endocrine tissues
Tropic Hormone
Cause secretion of another hormone that then travels to the target tissue to cause an effect
- Major effects in other endocrine tissues
What blood vessel system connects the hypothalamus with the anterior pituitary
Hypophyseal Portal System
Gonadotropin-releasing hormone (GnRH) from hypothalamus promotes the release of
Follicle stimulating hormone (FSH) and Luteinizing hormone (LH)
Target organ: Gonads (tested and overies)
Hormone released by target organ: Testosterone (testes) and estrogen/progesterone (ovaries)
Growth Hormone -releasing hormone (GHRH) from hypothalamus promotes the release of
Growth Hormone
Target organ: Bone, muscle
Hormone released by target organ: N/A
Thyroid- releasing Hormone (TRH) from hypothalamus promotes the release of
Thyroid- stimulating hormone (TSH)
Target Organ: Thyroid
Hormone released by target organ: Triiodothyronine (T3), Thyroxine (T4)
Corticotropin Releasing Factor (CRF) from hypothalamus promotes the release of
Adrenocorticotropic hormone (ACTH)
Target Organ: Adrenal Cortex
Hormone released by target organ: Glucocorticoids (Cortisol and cortisone)
Dopamine from hypothalamus promotes the release of
Prolactin
Target Organ: Breast Tissue
Hormone released by target organ: N/A
Prolactin Exception
As long as Hypothalamus releases PIF (dopamine), no prolactin is released. It is the absence of PIF that causes prolactin to be released
Interaction of the hypothalamus with the posterior pittuitary
Via the axons of nerves in the hypothalamus. Antidiuretic (ADH or vasopressin) and oxytocin are synthesized in the hypothalamus and then travel down these axons to the posterior pituitary, where they released into the bloodstream.
Anterior pituitary Products
FLAT PEG ( FLAT= tropic hormone and PEG= Direct Hormone)
Follicle stimulating hormone (FSH) Luteinizing hormone (LH) Adrenocorticotropic hormone (ACTH) Thyroid- stimulating hormone (TSH) Prolactin Endorphins Growth Hormone (GH)
Follicle stimulating hormone (FSH)
Source: Anterior Pituitary
Type: Peptide
Action: Stimulates the follicle maturation in females; spermatogenesis in males
Luteinizing hormone (LH)
Source: Anterior Pituitary
Type: Peptide
Action: Stimulates ovulation in females; testosterone synthesis in males
Adrenocorticotropic hormone (ACTH)
Source: Anterior Pituitary
Type: Peptide
Action: Stimulates the adrenal cortex to synthesize and secrete glucocorticoids
Thyroid- stimulating hormone (TSH)
Source: Anterior Pituitary
Type: Peptide
Action: Stimulates the thyroid to produce thyroid hormones
Prolactin
Source: Anterior Pituitary
Type: Peptide
Action: Stimulates milk production and secretion
Endorphins
Source: Anterior Pituitary
Type: Peptide
Action: Decreases sensation of pain; can produce euphoria
Growth Hormone (GH)
Source: Anterior Pituitary
Type: Peptide
Action: Stimulates bone and muscle growth; raises blood glucose levels and stimulates break down of fatty acids.
Stimulated by GHRH from hypo
Antidiuretic Hormone (ADH; Vasopressin)
Source: Anterior Pituitary
Type: Peptide
Action: Stimulates water reabsorption in the kidneys by increasing permeability of collecting duct. Thus, increased blood volume and blood pressure. Secreted in response to low blood volume or increased blood osmolarity
Oxytocin
Source: Hypothalamus (released by posterior pituitary)
Type: Peptide
Action: Stimulates uterine contraction during labor and milk secretion during lactation; may promote bonding behavior
Triiodothyronine (T3) and Thyroxine (T4)
Source: Thyroid (follicular cells)
Type: Amino-acid derivative
Action: Stimulates metabolic activity; greater T3 and 4 leads to increased cellular respiration and greater fatty acid and protein turnover
Calcitonin
Source: Thyroid (parafollicular or C cells)
Type: Peptide
Action: Decreases blood calcium concentration
Parathyroid hormone (PTH)
Source: Parathyroid
Type: Peptide
Action: Increases blood calcium concentrations by 3 ways
- Increase calcium reabsorption in kidneys (decreased excretion)
- increase bone resorption
- Increase absorption of calcium from the gut via activation of vitamin D
Glucocorticoids (cortisol and cortisone)
Source: Adrenal Cortex
Type: Steroid
Action: Increases blood glucose concentrations; decrease protein synthesis; antinflammatory
Mineralocorticoids (aldosterone)
Source: Adrenal Cortex
Type: Steroid
Action: Increases water reabsorption in the kidneys by increasing sodium reabsorption; promote potassium and hydrogen ion exchange
Epinephrine and norepinephrine
Source: Adrenal Medulla
Type: Amino-acid Derivative
Action: Increase blood glucose concentrations and heart rate; dilate bronchi; alter blood flow patterns
Glucagon
Source: Pancreas (Alpha-cells)
Type: Peptide
Action: Stimulates glycogen breakdown (glycogenoysis); increases blood glucose concentrations
Insulin
Source: Pancreas (Beta-cells)
Type: Peptide
Action: Lowers blood glucose concentrations and increases anabolic processes
Somatostatin
Source: Pancreas (Delta-cells)
Type: Peptide
Action: Suppresses secretion of glucagon and insulin
Testosterone
Source: Testis ( and adrenal cortex)
Type: Steroid
Action: Develops and maintains male reproductive system and male secondary sex characteristics
Estrogen
Source: Ovary (and placenta)
Type: Steroid
Action: Develops and maintains female reproductive system and female secondary sex characteristics
Progesterone
Source: Ovary (and placenta)
Type: Steroid
Action: Promotes maintenance of the endometrium
Melatonin
Source: Pineal Gland
Type: Peptide
Action: Involved in circadian rhythms
Erythropoietin
Source: Kidney
Type: Peptide
Action: Stimulates bone marrow to produce erythrocytes
Atrial natriuretic peptide (ANP)
Source: Heart (atria)
Type: Peptide
Action: Promotes salt and water excretion
Thymosin
Source: Thymus
Type: Peptide
Action: Stimulates T cell development
Which hormone does posterior pituitary receive and store?
ADH and Oxytocin
How are Triiodothyronine (T3) and Thyroxine (T4) produced
By the iodination of the amino acid tyrosine in the follicular cells of the thyroid
Which are the two hormones that are primarily involved in calcium homeostasis? and where do they come from?
Calcitonin from the parafollicular (C-) cells of the thyroid decreases blood calcium concentration. Parathyroid hormone from the parathyroid glands increases blood calcium concentration.
Which endocrine tissue synthesizes catecholamines? what are the two main catecholamines it produces?
The adrenal medulla synthesizes catecholamines, including epinephrine and norepinephrine
Which are the major drivers of glucose homeostasis? where does each come from and what effect does each have on blood glucose concentration?
Glucagon from alpha cells of the pancreas increases blood glucose concentration. Insulin from the Beta cells of the pancreas decreases blood glucose concentration.
Which 3 hormones are primarily involved in water homeostasis? Where is each one produced and what effect does it have?
- Antidiuretic hormone (ADH or vasopressin) from the hypothalamus and released by the posterior pituitary- it increases blood volume and decreases blood osmolarity.
- Aldosterone from the adrenal cortex- increases blood volume with no effect on blood osmolarity.
- Atrial natriuretic peptide (ANP) from the heart- decreases blood volume with no effect on blood osmolarity.
Renin angiotensin aldosterone
Decrease blood pressure cause the juxtaglomerular cells of kidney to secrete renin, which converts the inactive protein angiotensinogen to angiotensinogen II by enzyme angiotensin converting enzyme (ACE) in lungs.
angiotensinogen II causes adrenal cortex to secrete aldosterone
What hormones increase glucose levels?
Counterregulatory hormones such as
- glycogen
- growth hormone
- glucocorticoids
- epinephrine
