Endocrine System Flashcards
What is the difference between an endocrine and exocrine gland?

Endocrine glands release hormones directly into the bloodstream or tissues of the body.
Exocrine glands release chemical substances through ducts to outside the body or onto another surface within the body.

What are the different endocrine glands of the body?


What are the chemicals released, target effects, time of action and length of effect of the nervous system and endocrine sytem?

How do the nervous system and endocrine system work together?
Together, the nervous and endocrine systems coordinate functions of all body systems.
How do hormones and receptors work and cause regulation?
- Hormone target cells have receptors for hormones
- Upregulation is an increase in receptor density on the target cell
- Results in an increase in sensitivity
- Down Regulation is a decrease in receptor density on the target cell
- results in a decrease in sensitivity
- Negative Feedback mechanism

Walk through two examples of up-regulation and down-regulation?
Down-Regulation
-Too much of non-natural hormone like anabolic steroids causes down-regulation of receptors for testosterone bc theres so much testosterone in body
Up-Regulation
-Quit smoking after 6 yrs then up regulate the receptors for nicotine so you can get more into cells
What kinds of effects can hormones have on their target cells?
Hormones work together to cause:
- Synergistic effects
- two or more hormones combine to produce effects greater than the sum of their individual effects.
- Permissive Effects
- presence of one hormone, at a certain concentration, is required to allow a second hormone to fully affect the target cell
- Antagonistic effects
- return body conditions to within acceptable limits from opposite extremes

What are the types of hormones used in the body to regulate cells?
Circulating Hormones
- Endocrines: Endocrine cell makes hormone which is secreted from cell and diffuses into blood to finds target cell
Local Hormones
- Paracrines: non-circulating, local effect
- Autocrines: cell secretes hormone into interstitial fluid and the cell has receptors on itself

What are the characteristics of lipid-soluble hormones and what is their mechanism of action?
- steroid and thyroid hormones
- target cells use intracellular receptors
- hormone-receptor complexes
- altered gene expression
Receptor for lipid soluble usually located within cell (intracellular) because it can pass through plasma membrane
- the chemical produced by hormone intracellularly binds to mRNA which results in production of new protein
- oid or –one or –ol = steroid hormone

What are the characteristics of water-soluble hormones and what is their mechanism of action?
- catecholamine, peptide, and protein hormones
- target cells use membrane-bound receptors
- first messenger vs. second messenger
- G protein → adenylate cyclase → cAMP → protein kinase
- phosphodiesterase breaks down cAMP

What is enzyme amplification?
Cascade Effect
-1 hormone molecule amplified to 109 molecules in the body

Explain the control of hormone secretions to maintain glycemic homeostasis?
Negative Feedback Mechanism
- You eat and the glucose levels goes above 110 mg then body secretes insulin to bring glucose levels back down within range (90-110mg)

What are the structures pictured and what is their function?

Hypothalamus
- Master controller and regulator
- controls daily activities to keep the body alive
Pituitary Gland
- AKA=Hypophysis
- Infudibulum and Sella Tursica
- anterior and posterior controlled by hypothalamus

How does the anterior and posterior pituitary gland form during embryonic development?
Anterior Pituitary Gland (adenohypophysis)
- derived from Rathke’s pouch and breaks loose during embryonic development
- connected to hypothalamus through hypophyseal portal system
Posterior Pituitary Gland (neurohypophysis)
- an outgrowth of hypothalamus (directly connected)
- contains pituicytes
How does the Hypophyseal Portal System of the Anterior Pituitary Gland work?

Arterial Supply (carries RF from Hypothalamus) ⇒ Primary Plexus of Capillaries ⇒ Hypophyseal Veins ⇒ Secondary Plexus of Capillaries ⇒ Anterior Hypophyseal Veins

What are the hormones of the Anterior Pituitary Gland?
- Follicle-stimulating hormone (FSH)Growth hormone (GH, somatotropin)
- Luteinizing hormone (LH)
- Adrenocorticotropic hormone (ACTH, corticotropin)
- Thyroid-stimulating hormone (TSH, thyrotropin)
- Prolactin (PRL)
- Melanocyte-stimulating hormone (MSH)
What is a tropic hormone (tropin)?
From 1 endocrine organ to another endocrine organ
- Hypothalamic-pituitary-thyroid axis
- Hypothalamic-pituitary-adrenal axis
- Hypothalamic-pituitary-gonadal axis
What are the targets of the various tropic hormones?

How is secretion of growth hormone inhibited or promoted?
PROMOTION OF SECRETION
- HYPOGLYCEMIA (low blood sugar)
- decreased blood fatty acids
- increased blood amino acids
- deep sleep
INHIBITION OF SECRETION
- HYPERGLYCEMIA (high blood sugar)
- increased blood fatty acids
- decreased blood amino acids
- REM sleep
- obesity
- severe emotional states
How is Growth factor regulated? Walk through the chart.


What are the actions of growth factor?
- increased cellular uptake of amino acids = increased protein synthesis = growth/maintenance
- increased lipolysis and gluconeogenesis for energy, leading to hyperglycemia = diabetogenic effect
In adults GH is more about maintenance+repair
Walk throught the TSH mechanism.


Walk through the FSH mechanism for males

Gonadotropin ⇒ for FSH and for LH

Walk through the FSH Mechanism for females.


Walk through the LH (interstitial cell stimulating hormone) mechanism for males.


Walk through the LH mechanism for females.

Levels of estrogen:
- High = on (to make LH)
- Medium = off
- Low = on (to make FSH)
Follicles Mature = Increased Estrogen = Increased LH production = Ovulation

Walk through the Adrenocorticotropic Hormone mechanism.

Cortisol = Primary Glucocorticoid

What are the inhibition and stimulation pathways for Prolactin in females.


What are the characteristics of the posterior pituitary gland?
- Not really endocrine
- Contain Pituicytes (support cells)
- Hypothalamic nuclei carry signals down the Hypothalamo-hypophyseal tract to the Posterior Pituitary Gland which releases the following hormones:
- Oxytocin
- Anti-diuretic Hormone (ADH)

What are the effects of Oxytocin in Females?
Neuroendocrine reflex w/ Positive feedback mechanism
Target cells (no receptors for oxytocin prior to pregnancy)
- uterine smooth muscle
- stretch of cervix ⇒ release of oxytocin ⇒ smooth muscle contraction ⇒ more stretch of cervix (remove stretch on cervix stops pos. feedback)
- myoepithelial cells of mammary glands
- tactile stimulation or crying of a baby ⇒ oxytocin release ⇒ myoepithelial cells contract ⇒ milk is released (baby stop eating stops pos. feedback)
What is anti-diuretic hormone?

AKA = vasopressin
Hypothalamic osmoreceptors
Water reabsorption

What are the features of the Thyroid Gland?
- Located under the Hyoid Bone
- Follicular cells Produce:
- Triiodothyronine (T3)
- Tetraiodothyronine (T4, thyroxine)
- Parafollicular (C) cells Produce:
- Calcitonin which is stored in the Colloid

How does thyroid hormone secretion occur?
- Thryoid stores the secretory product
- Tyroisine atached to Thyroglobulin and captures iodide ions
- Cleaves from colloid and secreted as T3 and T4

Walk through the Thyroxine mechanism.


What are the characteristics of Calcintonin?
- Parafollicular (C-) Cells Produce calcitonin
- Hypercalcemia activates Calcitonin Secretion
- Results in Normocalcemia
What are the actions of calcitonin and walk through the mechanism of action.

Actions:
- inhibits osteoclasts
- stimulates osteoblasts
- decreased Ca++ reabsorption

What are the characteristics of the Parathyroid Glands and hormone?
- Located in the posterior side of thyroid
- Chief cells in Parathyroid gland release PTH
- Hypocalcemia = PTH secretion
- Results in Normocalcemia
What are the actions of Parathyroid Hormone and walk through the mechanism of action.

Actions:
- activates osteoclasts
- increased Ca++ absorption
- increased Ca+ reabsorption

What are the characteristics of the Adrenal (Suprarenal) Glands?

Located above the Kidney
Cortex is the outer “rind” and Medulla is the inner part
Adrenal Cortex produce steroids
Adrenal Medulla produce catecholamines
- Part of Nervous System
- Sympathetics
- Norepinephrine and Epinephrine
- Fight-or-Flight

What are the characteristics and actions of the Adrenal Cortex (zona glomerulosa)?
- Produce Mineralocorticoids (aldosterone) that regulate Electrolyte and fluid balance
- Aldosterone secretion in response to either:
- high blood [K+] (hyperkalemia)
- renin-angiotensin system (response to low blood press)
- Actions:
- decreased K+ reabsorption by kidneys
- Increased Na+ reabsorption by kidneys
What are the jobs, cause and results of Aldosterone?
Aldosterone released
- to control high K+ in blood
- because of low blood pressure
Aldosterone causes:
- decreased K+ reabsorption by kidneys
- Increased Na+ (and H2O) reabsorption by Kidneys
This Results in:
- Lowered K+ in blood
- Increased Blood Pressure
What are the characteristics of the Adrenal Cortex (Zona Fasciculata)?
Glucocorticoids (cortisol, hydrocortisone, cortisone)
Stress ⇒ C-RF ⇒ ACTH ⇒ glucocorticoids
Actions:
- Promote normal metabolism (increased glucose availability)
- Resistance to stress (increased alertness, energy, blood pressure)
- Anti-inflammatory (membrane stabilization)
Works through the Hypothalamic-pituitary-adrenal axis
Walk through the mechanism of action for Glucocorticoids.


What are the characteristics of the Adrenal Cortex (Zona Reticularis)?
Innermost layer of the Adrenal Cortex
Produce Gonadocorticoids
- androgens
- estrogens
Produces the sex hormones for body until onset of puberty when gonads take over
At menopause:
- ovaries don’t produce estrogen
- ona reticularis is primary produce of estrogen during menopause
What is the endocrine pancreas?
Located next to duodenum of small intestine
Contains Islets of Langerhans which contains the following cell types that produce hormones:
- Alpha Cells = glucagon
- Beta Cells = insulin
- Delta Cells = Somatostatin
- F Cells = Digestion
- G Cells = Gastrin
What are the characteristics of Glucagon?
- Produced by Alpha cells
- Hypoglycemia = glucagon secretion
- Actions:
- increased glycogenolysis
- increased gluconeogenesis
- Result = normoglycemia

What are the characteristics of Insulin?
- Produced by Beta cells of Islets of Langerhans in Pancreas
- Hyperglycemia = insulin secretion
- Actions:
- increased glucose uptake
- increased glycogenesis
- increased lipogenesis
- Result = normoglycemia
- Diabetes mellitus caused by lack of insulin production and insulin insensitivity
What is the general adaptation sysndrome?
Response to Stress
Stressor causes the Hypothalamus to release:
- C-RF ⇒ ACTH ⇒ Glucocorticoids
- Peripheral Nervous System ⇒ Epinephrine+Norepinephrine ⇒ Increased Blood Pressure
If stressor doesn’t stop reach Exhaustion Phase:
- Decreased resistance to disease = Death
- Hypertension ⇒ Cadiac/Renal Failure = Death
