Lecture 18 - Endocrine System Flashcards
the collection of glands and tissues of the body that secrete chemical messengers (hormones) into the blood
endocrine system
what is a hormone?
a chemical messenger that is produced and secreted by an endocrine cell or tissue, travels through the circulatory system to reach other tissues, and acts upon specific target cells within the tissues
the prescence or abscence of a receptor determines the cell’s:
response to a hormone
changing the number of receptors at a certain tissue changes the cell’s:
sensitivity to the hormone
the nervous system has ______ activity, while the endocrine system has ______ activity
highly specific, widespread
how long is the duration of nervous system action versus endocrine system action?
nervous system = short term (milliseconds to minutes)
endocrine system = long duration (minutes to days)
while the nervous system is better for creating rapid responses to environmental stimuli, the endocrine system is better for:
regulation of ongoing processes such as growth
endocrine gland located anterior to the trachea and just inferior to the larynx; it is anchored to the first 2-3 tracheal rings and has a butterfly shape
thyroid gland
the right and left lobes of the thyroid gland are joined by an:
isthmus
thyroid follicles are filled with a viscous protein-rich fluid called _____, and are surrounded by follicular cells called _____
colloid, T-thyrocytes
T-thyrocytes produce a large protein called _____, and store it in the _____ of the follicle
thyroglobulin (Tg), lumen
the T-thyrocytes pump _____ into the lumen, and enzymes on their luminal surface will add _____ to the _____
iodine, iodine, thyroglobulin (Tg)
hormone which induces thyrocytes to remove thyroglobulin from the lumen, cleave off T3, T4, and release them into the blood
thyroid stimulating hormone (TSH)
thyroid hormones are derivatives of:
tyrosine
the thyroid releases mainly _____, but _____ is the more active form. peripheral tissues can convert ______ to ______. both regulate ______
thyroxine (T4), triiodothyronine (T3), T4, T3, metabolism
too little thyroid hormone regulation leads to:
weight gain, fatigue, depression
too much thyroid hormone regulation leads to:
weight loss (muscles), anxiety, difficulty sleeping, irregular heartbeat
the hypothalamus and pituitary act as master regulators of:
the endocrine system
the anterior lobe of the pituitary gland is known as the:
adenohypophosis
the posterior lobe of the pituitary gland is known as the:
neurohypophosis
part of the pituitary which contains cuboidal epithelial cells typical of an endocrine gland (produces lots of different hormones)
the adenohypophosis
part of the pituitary which contains nerve terminals and no glandular cells
the neurohypophosis
the adenohypophosis is part of what system?
the hypothalamic-hypophyseal portal system
list the steps that a signal follows through the hypothalamic-hypophyseal portal system
1) neurosecretory cells in the hypothalamus releases hormones into the primary capillary plexus (blood comes in from superior hypophyseal artery)
2) signal travels down the portal veins
3) signals arrive at the secondary capillary plexus
4) endocrine cells in the adenohypophysis receive the signal
5) hormones secreted and sent down efferent veins
list the hormones produced by the adenohypophysis (time to remember your goatflap hormones)
- human growth hormone (hGH)
- thyroid stimulating hormone (TSH)
- follicle stimulating hormone (FSH)
- luteinizing hormone (LH)
- prolactin (Prl)
- adrenocorticotropic hormone (ACTH)
hormone which stimulates body growth and metabolism
human growth hormone (hGH)
hormone that controls thyroid gland function
thyroid stimulating hormone (TSH)
hormones which control secretion of sex hormones and production of gametes
follicle stimulating hormone (FSH) and luteinizing hormone (LH)
hormone which stimulates milk production
prolactin (Prl)
hormone which controls hormone sectretion by the adrenal cortex (stimulates glucocorticoid secretion)
adrenocorticotropic hormone (ACTH)
list the steps that a signal follows through the neurohypophysis?
1) neurosecretory cells of the supraoptic nucleus and paraventricular nucleus are stimulated
2) signal travels through the infundibulum along the hypothalamohypopyseal tract, but skips the portal system
3) signals is received at the capillary plexus of the neurohypophysis (blood comes from the inferior hypophyseal artery)
4) hormones sent into circulation by efferent veins
which hormones are secreted by the neurohypophysis?
- vasopressin (aka antidiuretic hormone (ADH))
- oxytocin
hormone which regulates the concentration of urine and functions in the regulation of blood pressure
vasopressin/antidiuretic hormone (ADH)
which hormone is made by the neurons of the supraoptic nucleus?
vasopressin/antidiuretic hormone (ADH)
hormone which stimulates uterine muscle contraction during and after childbirth, and stimulates the release of milk from the mammary glands
oxytocin
which hormone is made by the neurons of the paraventricular nucleus?
oxytocin
which hormone stimulates the release of ACTH?
corticotropin releasing hormone (CRH)
which hormone stimulates the release of TSH?
thyroid releasing hormone
where are the adrenal (suprarenal) glands located?
on top of the kidneys (like hats for your kidneys)
the adrenal cortex contains glandular tissue which stores ____ and ____ to use in the synthesis of ____
cholesterol, fatty acids, >24 steroid hormones (corticosteroids)
the adrenal medulla contains ____ and ____
blood vessels, other glandular tissues
what are the three zones of the adrenal cortex?
- zona glomerulosa
- zona fasciculata
- zona reticularis
part of the adrenal cortex which responds to ACTH and releases glucocorticoids (ex: cortisol)
zona fasciculata
hormones of the adrenal cortex which control a number of physiological functions for both resting homeostasis and in response to stress; used for immunosuppressive and anti-inflammatory properties
glucocortoids
part of the adrenal cortex which releases mineralocorticoids (ex: aldosterone)
zona glomerulosa
hormones of the adrenal cortex which controls electrolyte balance, increases renal absorption of sodium and water, and decreases renal absorption of potassium
mineralocorticoids
part of the adrenal cortex which releases androgens (aka sex hormones)
zona reticularis
hormones of the adrenal cortex which stimulates growth of axillary and pubic hair, and their release is partially stimulated by ACTH
androgens
why is the zona reticularis more important in adult females than males?
because males can get their androgens from their testes, but females don’t have those
pre-ganglionic sympathetic fibres stimulate _____ cells in the adrenal medulla
chromaffin cells
what are chromaffin cells?
neuroendocrine cells of the adrenal medulla which act as post-ganglionic neurons to stimulate the release of epinephrine/norepinephrine into the blood (fast response to stress)
hormones which act in the fight or fight response to increase cardiac output, blood pressure, and blood glucose, and that effect the release of lipids from adipose tissue
epinephrine and norepinephrine
the endocrine cells in the pancreas are called:
Islets of Langerhans
list the three main hormones secreted by the pancreas
glucagon, insulin, and somatostatin
in the Islets of Langerhans, glucagon is secreted by:
alpha cells
in the Islets of Langerhans, insulin is secreted by:
beta cells
in the Islets of Langerhans, somatostatin is secreted by:
delta cells
what are the three main functions of glucagon?
- stimulates glucose synthesis
- elevates blood glucose
- mobilizes lipid reserves
what are the three main functions of insulin?
- stimulates lipid and glycogen synthesis and storage
- stimulates glucose uptake by cells
- decreases blood glucose levels
what is the main function of somatostatin?
inhibits secretion of glucagon and insulin
produced by enteroendocrine cells of the intestines in response to glucose; stimulates insulin secretion and inhibits glucagon secretion
glucagon-like peptide 1 (GLP-1)
disease characterised by an inability to produce or use insulin which results in elevation of blood glucose levels (hyperglycemia) and excretion of glucose in the urine
diabetes mellitus
autoimmune disease that destroys insulin-secreting cells of Islets (beta cells) resulting in a marked reduction of insulin levels
Type I diabetes (aka insulin-dependent diabetes)
at what age does Type I diabetes develop?
can occur at any age is more common between ages 5-20
disease with a combination of insulin-resistance and insulin secretory defects where the target cells become less sensitive to insulin due to the down-regulation of receptors
Type II diabetes (non-insulin-dependent diabetes)
how is Type II diabetes managed?
diet, exercise, and weight loss
hormone produced by the parathyroid glands
parathyroid hormone
where are the parathyroid glands found?
ususally sit posterior to the thyroid gland
what is the function of parathyroid hormones?
increases Ca++ in body fluids and decreases Ca++ deposition in bone
hormone produced by C-cells in the thyroid gland, but are completely separate from other thyroid functions
calcitonin
what is the function of calcitonin?
decreases Ca++ in body fluids and increases Ca++ deposition in bone
small midline strucutre at the posterior end of the third ventricle which secretes melatonin and regulates the circadian rhythym
pineal gland
produces T-lymphocytes and secretes thymic hormones (promotes proliferation and maturation of T-lymphocytes)
thymus gland
