Endocrine System (KT) Flashcards
General characteristics of the endocrine system (3)
- Chronic regulation of homeostasis
- Slow and prolonged responses
- Interrelated with the nervous system (hypothalamus and posterior pituitary)
Ductless system characteristics (2)
- Hormones produced by specialized cells
2. Carried in blood stream
Substance synthesized by a specific organ or tissue and secreted
Hormone
Hormone secreted into extracellular spaces
Paracrine Signaling
Blood carries hormones to other sites
Endocrine signaling
Hormones act on target cells that…
Have specific receptors for specific hormones
4 Categories of Hormones
- Steroids
- Peptides
- Amines
- Eicosanoids
Hormone that is…
- Made of cholesterol and is nonpolar
- Lipid soluble and can cross the cell membrane
- Transduction –> Regulation of DNA transcription
Steroids
Examples of steroids (4)
- Estrogens like estradiol
- Androgens like testosterone
- Aldosterone
- Cortisol
Hormone that is
- Derived from amino acids
- Derived from tyrosine or tryptophan
- Polar or non polar
Amine Hormones
Example of an amine hormone that is membrane soluble
Thyroxine
Example of amine hormone that is not membrane soluble
Epinephrine
Most important amine hormones are made by… (2)
- Thyroid
2. Adrenal Medulla
Hormone that is…
- Short chains of amino acids
- Cannot cross cell membrane
- All pituitary hormones
Peptide Hormones
Hormone that is…
- Derived from fatty acids
- Most cross the cell membrane
- Coordinate functions in extracellular fluid
Eicosanoids
Example of an eicosanoid
Prostaglandins
Characteristics of a Negative Feedback Loop (4)
- Gland is sensative to a concentration of a substance
- Concentration exceeds limits–> prevents gland from secreting hormone
- Concentration decreases–> secretion increases
- Results in relatively stable concentration of both substance and hormone
The hypothalamus sends signals to the… (2)
- Body
2. Pituitary Gland
- This is really 2 separate glands, developmental origins are key to function
- Most important endocrine gland for regulation
Pituitary Gland
The 2 lobes of the pituitary gland
- Posterior
2. Anterior
Lobe that…
- Does not make any hormones
- Mostly hypothalamic axons
Posterior Lobe of the Pituitary Gland
Lobe that…
- Has 5 types of endocrine cells
- Controlled by hypothalamic regulatory hormones
Anterior Lobe of the Pituitary Gland
2 types of Regulatory Hormones
- Releasing hormones
2. Inhibiting Hormones
Posterior Pituitary Hormone…
-Oxytocin (4)
- Causes contraction of muscles in the uterine walls
- Causes muscles associated with milk ejection to contract
- Causes contraction of the prostate gland
- Significant in emotional bonding (familial and romantic)
Posterior Pituitary Hormone…
-Anti-diuretic Hormone (ADH) (2)
- Causes kidney to decrease water excretion
2. Increases blood volume–> rise in blood pressure
Anterior Pituitary Hormone…
-Melanocyte Stimulating Hormone (MSH) Characteristic (1)
- Increase melanin secretion
Anterior Pituitary Hormone…
-Follicle Stimulating Hormone (FSH) (3)
- Testes to produce sperm
- Follicular development in ovaries
- Stimulate secretion of estrogen
Anterior Pituitary Hormone…
-Luteinizing Hormone (LH) (2)
- Promotes secretion of sex hormones
2. Release of oocyte
Anterior Pituitary Hormone…
-Growth Hormone (GH) (4)
- Increase in size and rate of reproduction of body cells
- Targets muscles and bones- mobilizes fat and glucose
- Enhances movement of amino acids through membranes
- Secreted throughout life, really increase at puberty
Anterior Pituitary Hormone…
-Thyroid Stimulating Hormone (TSH)
- Controls secretion of thyroid hormone
Anterior Pituitary Hormone…
-Prolactin (PRL) (2)
- Targets mammary tissue
2. Milk production and secretion
Anterior Pituitary Hormone…
-Adrenocorticotropic Hormone (ACTH)
Stimulates the adrenal cortex to produce corticosteroids
Structure of the thyroid gland (3)
- 2 lobes and isthmus (inferior to larynx)
- Follicular Cells
- Parafollicular Cells
Characteristics of Follicular Cells (4)
- Line follicle cavities
- Filled with thyroglobulin colloid
- Remove iodine from the blood
- Secrete t3 and T4
What do parafollicular cells produce?
Produce calcitonin
Thyroid Hormones (2 types of cells)
- Follicular Cells (Thyroxine and Triiodothyronine)
2. Parafocllicular Cells (Calcitonin)
Effects of Thyroxine, T4 (3)
- Increase Glycogenolsis
- Increase protein synthesis
- Increase growth
Effects of Triiodothyronine T3 (3)
- Increase Glycogenolsis
- Increase protein synthesis
- Increase growth
* 5 times stronger than T4
Effects of Calcitonin (3)
- Decrease blood calcium and phosphorus
- Increase renal excretion
- Increase osteoblast activity
Where are parathyroid gands located?
-Posterior surface of thyroid
What does the parathyroid consist of?
-Many tightly packed secretory cells
Immature parathyroid cells
Oxyphil and transitional cells
What are chief cells?
-Produce parathyroid hormone
What does the parathyroid hormone do? (4)
- Increase blood calcium
- Decrease renal calcium and phosphorus excretion
- Increase osteoclast activity
- Increase calcitriol = intestinal calcium absorption
Where is the thymus located?
Thoracic cavity, posterior to sternum
What does the Thymus produce?
Thymosin
What does thymosin do?
- Enhances lymphocyte production and competence
2. Most active in infancy and childhood
What are the components of the adrenal cortex? (3)
- Glomerulosa
- Fasciculata
- Reticularis
In the glomerulosa…
Aldosterone –> Na and retention
In the fasciculate…
Cortisol –> Glycogen formation
In the reticularis…
Androgens –> Secondary sexual characters
The adrenal medulla consists of…
Chromaffin cells which are modified postganglionic cells of the SNS (Epinephrine and norepinephrine)
3 hormones of the Kidney…
- Renin
- Erythropoietin (EPO)
- Calcitriol
What does Renin do? (1)
- Start cascade to increase blood pressure
What does Erthropoietin do? (1)
- Erthrocyte production
What does Calcitriol do?
- Increases absorption of digested calcium
What is the hormone of the heart? (1)
- Atrial Natriuretic Peptide (ANP)
What does the Atrial Natriuretic peptide hormone do? (2)
- Suppresses aldosterone and ADH
2. Decrease blood volume and blood pressure
Where is the pancreas located?
Posterior to stomach
- Attached to duodenum by duct
- Exocrine and endocrine function
- Have endocrine function
- Consist of alpha cells, beta cells, and delta cells
Islets of Langerhans
What do alpha cells do?
Glucagon = Increases blood sugar
What do beta cells do?
Insulin = Decrease blood sugar
What do delta cells do?
Somatostatin- inhibits glucagon and insulin secretion
-antagonizes GH
What do interstitial cells do?
-Secrete andogens
What does testosterone do?
- Stimulate nurse cells
- Secondary sex characteristics
What do nurse cells do?
Secrete inhibin
- Decrease FSH from anterior pituitary
- Stimulates spermatogenisus
What does estrogen in the follicles do?
- Maturation of the oocyte
- Endometrial development
What does inhibin do in the female gonads?
-Decrease FSH from anterior pituitary
Follicles–>
Pre-ovulation
Corpus Luteum–>
Post-ovulation
What does estrogens in the corpus luteum do?
- Maturation of the oocyte
- Endometrial development
What does progesterone do?
-Prepares body for pregnancy
Where are pineacytes located?
Epithalamus
What does the pineal gland secrete?
-Melatonin
What does melatonin control?
Circadian Rhythms
What hormones does the posterior pituitary secrete? (2)
Oxytocin and antidiuretic hormone.
9What hormones does the anterior pituiatary secrete? (7)
- Melanocyte stimulating hormone
- Follicle stimulating hormone
- Luteinizing hormone
- Growth hormone
- Thyroid stimulating hormone
- Prolactin
- Adrenocorticotrophic hormone
