Unit 4: Endocrine Physio Flashcards
Define “hormone,” and “target cell”.
Hormone- chemical secreted by a cell(s) into the blood for transport to a target where it acts in low concentrations to affect growth/homeostasis/metabolism
target cell- a cell that has a receptor, therefore has ability to bind to the hormone and recognize its presence
Compare and contrast between endocrine and exocrine glands.
endocrine glands are ductless and can only secrete cellular signals in the form of a hormone
exocrine glands can secrete many different molecule types and they will move through a duct to destination
Compare and contrast between the endocrine and the nervous systems
endocrine system
~cellular signal starts out as a chemical; chemical is carried by bloodstream to a target cell [also being carried to all other cells but only recognized by target cells with receptors]
~signal is transported to selected target cells that respond to the presence of the endocrine hormone
~slower response time (secretion of endocrine cell into blood, transportation takes time, response)
~chemical signal is an endocrine hormone
nervous system
~bulk of message is carried electrically down neuron length
~signal delivery much faster
~signal is distributed only to terminal synapse (more localized/targeted)
~chemical signal is a neurotransmitter
Describe the different mechanisms of endocrine tissue control.
A. Nervous (ex- adrenal medulla)
B. Humoral (ex- blood glucose level)
C. Hormonal (ex- hypothalamic releasing hormones)
D. Feedback (via any above mechanisms)
Describe the different chemical classifications used to describe hormones.
A. Water soluble/ membrane impermeable
i. Polypeptide (amino acid derived)
ii. Catecholamine (amino acid derived)
[cannot enter cell, can only interact with target cells exteriorly]
B. Water Insoluble/ membrane permeable
i. steroid
ii. thyroid hormones (amino acid dervied)
[require some carrier within the blood]
Describe the steps in the cAMP second messenger system.
What type of hormone (chemical classification) uses this activation system?
Water soluble hormones (they cannot cross membrane)- polypeptides & catecholamine
1) signal molecule binds to G protein linked receptor, activating G protein
2) G protein turns on Adenylyl cyclase (an amplifier enzyme)
3) Adenylyl cyclase converts ATP into Cyclic AMP (cAMP)
4) cAMP activates protein kinase A
5) Protein kinase A phosphorylates other proteins, leading to cellular response in target cell
Describe the steps in the calcium second messenger system.
What type of hormone (chemical classification) uses this activation system?
Also used by water soluble/ membrane impermeable hormones- polypeptides & catecholamine
1) signal molecule activates the receptor and associated G protein
2) G protein activates phospholipase C (Pl-C, an amplifier enzyme)
3) Pl-c converts membrane phospholipids into ip3, which diffuses into cytoplasm
4) Ip3 causes release of calcium from organelles, creating a calcium signal
Describe the steps in target cell activation by steroid hormones.
Hormone bound to receptor becomes active & can move into nucleus and attach to DNA
when attached to DNA at a promoter site, DNA segment can make copies of itself in form of mRNA
mRNA is shuttled out into cytoplasm and used for protein synthesis
Describe the steps in target cell activation by thyroid hormones.
Hormone is bound to plasma carrier protein
Binding to a target cell activates the prehormone (T4 > T3)
T3 moves in nucleus and binds to receptor protein that is attached to DNA; binding will trigger RNA production which will be used for protein synthesis
Describe the process of up and down regulation and its significance.
Target cell property
Up regulation- Some will at their tonic level of hormone exposure have very little responsiveness (not many receptors for a hormone), but as hormone levels rise, the cells produce more receptors > cell is more responsive to hormone
up-regulation can also occur when hormone levels decline [increasing sensitivity to lower hormone levels]
Down regulation- ex) insulin in diabetic; target cells decrease # receptors if hormone levels rise if they are chronically elevated [receptors removed and become less sensitive to hormone]
~can also occur if hormone levels drop
Name each of the lobes of the pituitary and describe the structure (origin) of each lobe.
3 main zones
~posterior pituitary [made of neural tissue] AKA neurohypophysis; produces 2 meaningful hormones
~intermediate pituitary [tiny sliver in the center of the gland]; secretes one hormone
~anterior pituitary [6 cell types- epithelial cells that secrete 7 hormones]
Describe the relationship between the hypothalamus and the anterior pituitary.
The hypothalamus releases neurohormones that affect the anterior pituitary
[the neurohormones will stimulate or inhibit anterior pituitary cells]
Identify all of the hormones produced by the anterior pituitary and the general function of each.
How many regulate the function of another endocrine gland?
- Prolactin: more dramatic role in females; act on glandular breast tissue to stimulate milk production
- Growth hormone: acts on multiple tissue types to stimulate growth
- thyroid stimulating hormone (TSH): stimulated thyroid gland (follicular cells of the gland)
- Adrenocorticotropic hormone (ACTH): targets adrenal cortex
- Follicle stimulating hormone (FSH): follicle growth within the ovary
- Leutanizing hormone (LH): triggers ovulation
Describe the relationship between the hypothalamus and the posterior pituitary
The hypothalamus synthesizes the hormones stored and released by the posterior pituitary [ADH, oxytocin]
Identify the hormones secreted by the intermediate and posterior pituitary and describe the general function of each
Posterior pituitary [2]
~Anti diuretic hormone ADH: stimulates increased reabsorptive potential of collecting duct by increasing water permeability with aquaporins [decreased urine]
~Oxytocin: smooth muscle stimulator resulting in smooth muscle contraction
intermediate pituitary [1]
~Melanocyte stimulating hormone MSH: stimulates melanocytes [found in skin- pigment]- minimal role
Describe the endocrine and exocrine structure of the pancreas.
99% exocrine structure
~pancreatic acinar cells: secrete protein/lipid/carb digesting enzymes, buffering agents down the ductwork into small intestine for digestion
1% endocrine structure
~pancreatic islets (of Langerhans) [ductless]
~insulin & glucagon production
Identify the different cell types of the endocrine pancreas and their products.
Beta cells produce insulin
Alpha cells produce glucagon
Describe the function of insulin on cells in general, on liver tissues, on adipose tissues and on skeletal muscle tissues.
General- increases cellular uptake of blood glucose [lowering blood glucose]
Liver & skeletal muscle tissue: convert glucose into glycogen for storage [glycogenesis] may be shorter term
adipose tissue: glucose converted into triglyceride molecules [lipogenesis] longer-term conversion
Describe the function of glucagon on cells in general, on liver tissues, on adipose tissues and on skeletal muscle tissues.
General- antagonistic to insulin in metabolism effect; increases blood glucose levels
Liver & skeletal muscle tissue: converts glycogen or other non-carb molecules to glucose [glycogenolysis]
Adipose tissue: lipolysis; no change in blood glucose; release of ketones into blood (fuel source in absence of glucose)
Distinguish between type I (IDDM) and type II (NIDDM) diabetes mellitus.
Type 1: very severe; [juvenile onset]; due to early autoimmune error that kills all beta cells; deficient in insulin production
Type 2: Adult onset; response of target cells which are down-regulating and not responding to insulin as much as they should; typically due to diet that leads to chronically elevated insulin levels > down-regulation
Compare and contrast between diabetes mellitus and diabetes insipidus.
diabetes mellitus: lack/abnormal insulin action
diabetes insipidus: lack of vasopressin (ADH)
Both marked by frequent urination [polyurea]
What are the cardinal symptoms of diabetes mellitus (three P’s)? Explain how each symptom comes about.
Polyphagia- extreme hunger
Polyuria- increased urination (due to increased osmotic conc. of filtrate caused by hyperglycemia)
Polydipsia- extreme thirst
Identify the different hormones of the thyroid gland, their specific origin and their general function.
Secretes 2 key hormones
triiodothyronine T3
thyroxine T4
^ both responible for regulating metabolic rate; role in negative feedback loop; become self-regulatory; dependent on iodine
[insufficient iodine> leads to large thyroid gland]
[also calcitonin, but not as important]
Identify the hormone of the parathyroid gland and its general function.
Parathyroid hormone
targets mainly kidneys & bone
Kidneys: reabsorption of Ca2+ calcium [increases blood calcium & decreases urinary excretion of calcium]
Bone: dissolution of calcium phosphate crystal> increases blood calcium [negative feedback]
Identify the different hormones of the adrenal gland, their specific origin and their general functions.
Adrenal cortex - 3 zones
Zona glomerulosa: mineralocorticoid AKA ALD [Na reabsorption, K secretion]
Zone fasciculata: glucocorticoids [ex) cortisol- blood glucose regulation, anti-inflammation]
Zona reticularis: sex hormones (testosterone, etc, but not as much as in sex organs)
Adrenal medulla (core)
Norepinephrine: neurotransmitter produced & secreted by post-ganglionic sympathetic neurons
Epinephrine
Dopamine
__________ ________ are glands that release a secretion into interstitial space; then the molecule can migrate and enter the bloodstream
[ductless glands]
endocrine glands
________ ______ always have ducts; products are secreted into a duct> moves through to duct to a destination (internal or external space)
exocrine glands
Endocrine glands secrete :
cellular signals [chemicals]; transported in blood- unique label of hormone
Exocrine glands can secrete :
various molecules such as enzymes, buffers, acids, protein water mix, etc…
While exocrine glands can secrete several molecule types, endocrine glands only secrete:
cellular signals in the form of hormones
Hormones are named as such if found in the:
blood
________ _____ is a cell that has a receptor and, therefore can bind to the hormone and recognize its presence
target cell
which cell is the target cell is determined by:
the cells, not by the hormone or endocrine gland
the _________ __________ produces and secretes the endocrine hormone
endocrine tissue