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46 Cards in this Set
- Front
- Back
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Paracrine signaling
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a form of cell signaling in which the target cell is near ("para" = near) the signal-releasing cell
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Endocrine signaling
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Increase in an intracellular molecule due to stimulus results in exocytosis of a secretory material.
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Endocrine glands
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glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct. The main endocrine glands include the pituitary gland, pancreas, ovaries, testes, thyroid gland, and adrenal glands.
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Neurohemal organ
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The hypothalamus is a neuroendocrine organ.
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Three classes of second
messengers |
1. Cyclic nucleotides
2. DAG and IP3 3. Calcium ion |
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Calmodulin
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A cytosolic protein with 4 binding sites for Ca: an important intracellular regulator.
In all animal and plant tissues. mediates processes such as inflammation, metabolism, apoptosis, muscle contraction, intracellular movement, short-term and long-term memory, nerve growth and the immune response Many of the proteins that CaM binds are unable to bind calcium themselves, and as such use CaM as a calcium sensor and signal transducer |
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Hypothalamus
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synthesizes and secretes neurohormones, often called hypothalamic-releasing hormones, and these in turn stimulate or inhibit the secretion of pituitary hormones. The hypothalamus controls body temperature, hunger, thirst, fatigue, anger, and circadian cycles
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What are the effects of glucocorticoids?
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Metabolic effects:
* Stimulation of gluconeogenesis, particularly in the liver: This pathway results in the synthesis of glucose from non-hexose substrates such as amino acids and glycerol from triglyceride breakdown. * Mobilization of amino acids from extrahepatic tissues: These serve as substrates for gluconeogenesis. * Inhibition of glucose uptake in muscle and adipose tissue: A mechanism to conserve glucose. * Stimulation of fat breakdown in adipose tissue: The fatty acids released by lipolysis are used for production of energy in tissues like muscle, and the released glycerol provide another substrate for gluconeogenesis. • Muscle: net loss of AA: released into circulation, conversion to glucose in liver. |
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Gluconeogenesis
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Gluconeogenesis is also a target of therapy for type II diabetes, such as metformin, which inhibit glucose formation and stimulate glucose uptake by cells.
This process occurs during periods of fasting, starvation, or intense exercise and is highly endergonic. synthesis of glucose from compounds other than carbohydrates (fats, AA) |
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Thyroid glands
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The thyroid participates in these processes by producing thyroid hormones, principally thyroxine (T4) and triiodothyronine (T3). These hormones regulate the rate of metabolism and affect the growth and rate of function of many other systems in the body.
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What is the trigger for TRH (thyrotropin-releasing hormone) release?
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produced by the hypothalamus and secreted at an increased rate in situations such as cold (in which an accelerated metabolism would generate more heat)
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How is Hypothyroidism treated?
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T4 Only
This treatment involves supplementation of levothyroxine alone, in a synthetic form. It is currently the standard treatment in mainstream medicine. T4 and T3 in Combination This treatment protocol involves administering both synthetic L-T4 and L-T3 simultaneously in combination. Desiccated Thyroid Extract Desiccated thyroid extract is an animal based thyroid extract, most commonly from a porcine source. It is also a combination therapy, containing natural forms of L-T4 and L-T3. |
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How is Hyperthyroidism treated?
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Thyrostatics- drugs that inhibit the production of thyroid hormones, such as carbimazole (used in UK) and methimazole (used in US), and propylthiouracil
Many of the common symptoms of hyperthyroidism such as palpitations, trembling, and anxiety are mediated by increases in beta adrenergic receptors on cell surfaces. Beta blockers are a class of drug which offset this effect, reducing rapid pulse associated with the sensation of palpitations, and decreasing tremor and anxiety. remove the whole thyroid or a part of it radioactive iodine-131 is given orally (either by pill or liquid) on a one-time basis to destroy the function of a hyperactive gland |
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Insulin
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Insulin causes most of the body's cells to take up glucose from the blood (including liver, muscle, and fat tissue cells), storing it as glycogen in the liver and muscle, and stops use of fat as an energy source. When insulin is absent (or low), glucose is not taken up by most body cells and the body begins to use fat as an energy source (ie, transfer of lipids from adipose tissue to the liver for mobilization as an energy source)
lowers blood-glucose levels. Released from Beta cells if high Glucose levels and by GIP. |
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Diabetes mellitus
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Type 1 diabetes mellitus is characterized by loss of the insulin-producing beta cells of the islets of Langerhans in the pancreas, leading to a deficiency of insulin. This type of diabetes can be further classified as immune-mediated or idiopathic. The majority of type 1 diabetes is of the immune-mediated variety, where beta cell loss is a T-cell mediated autoimmune attack.
Type 2 diabetes mellitus is characterized differently and is due to insulin resistance or reduced insulin sensitivity, combined with relatively reduced insulin secretion which in some cases becomes absolute. The defective responsiveness of body tissues to insulin almost certainly involves the insulin receptor in cell membranes. |
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Glucagon
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released when the glucose level in the blood is low (hypoglycemia), causing the liver to convert stored glycogen into glucose and release it into the bloodstream. The action of glucagon is thus opposite to that of insulin, which instructs the body's cells to take in glucose from the blood. However, glucagon also paradoxically stimulates the release of insulin, so that newly available glucose in the bloodstream can be taken up and used by insulin-dependent tissues.
raises blood-glucose levels. Released by Alpha cells if low glucose levels (hypoglycemia). |
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What are the effects of Growth Hormone?
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* Increases calcium retention, and strengthens and increases the mineralization of bone
* Increases muscle mass through sarcomere hyperplasia * Promotes lipolysis * Increases protein synthesis * Stimulating the growth of all internal organs excluding the brain * Plays a role in fuel homeostasis * Reduces liver uptake of glucose * Promotes gluconeogenesis in the liver- anti-insulin effect * It contributes to the maintenance and function of pancreatic islets * It stimulates the immune system |
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What is a pheromone?
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chemical signals that carry messages between different individuals of a species
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What is the simple endocrine pathway?
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-stimulus
-receptor protein -endocrine cell -blood vessel -target effectors -response |
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What is a neurosecretory cell?
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-release hormones into the blood via the extracellular fluid
-AP results in increase of intracellular Ca and exocytosis of secretory material near capillary. |
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How are secretory proteins produced?
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Synthesis in rough ER
Packaged in vesicles in Golgi complex. Insertion into apical membrane. Exocytosis of material. |
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What are 4 major classes of hormones?
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Amines, Prostaglandins, Steroids, and Peptides
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What is cortisone?
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-released by the body as a reaction to stress. It elevates blood pressure and sugar and prepares the body for a fight or flight response.
-suppresses the immune system. This could be the explanation for the apparent correlation between high stress and sickness. |
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What is cortisol?
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-involved in response to stress and anxiety, controlled by Corticotropin-releasing hormone
-increases blood pressure and blood sugar, and reduces immune responses. |
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What stimulates Growth Hormone Releasing Hormone (GRH) from the pituitary gland?
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low blood glucose levels
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How does growth hormone stimulate growth?
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1. Directly, # cells
2. Indirectly, liver produces growth-promoting factors => cell production. |
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What releases Juvenile Hormone?
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corpus allatum
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What releases ecdysone?
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prothoracic gland
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What causes larval molting?
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ecdysone + high juvenile hormone
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What causes pupation (larva to pupa molt)?
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ecdysone + low juvenile hormone
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What causes the pupa to adult molt?
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ecdysone + no juvenile hormone
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What is Dalton's Law of Partial Pressure?
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partial pressure of gas in air=% gas x total air pressure
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What is Henry's Law of Gas Solubility?
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amount of gas in solution=partial pressure x solubility
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What is the effect of pH on hemoglobin-O2 affinity?
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-increase in pH: increase O2 affinity
-decrease in pH: decrease O2 affinity -local conditions control O2 transport |
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What promotes the secretion of glucocorticoids?
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starvation, a diurnal rhythm, corticotropin releasing hormone, and adrenocorticotrophic hormone
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Specificity of hormone action is due to...
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target cells (receivers)
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What is the bundle of His?
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spreads stimulatory impulses from the pacemaker area over the ventricular muscles
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What are 3 ways material is moved across the capillary endothelial cells?
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-pinocytosis
-pores in endothelial cells -paracellular gaps |
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Carbon dioxide leaves the blood as
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molecular carbon dioxide
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What forms can carbon dioxide be transported in the blood?
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-bicarbonate
-molecular carbon dioxide -carbamino compounds -carbonic acid |
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Endothelial control of capillary blood flow is due to
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Nitrogen Oxide
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What are the results of Hypothyroidism?
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an overall low metabolism
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What is biochemical amplification?
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-a few molecules activate an enzyme which can produce many product molecules.
-If product can activate other enzymes, the reaction chain has a snowball effect |
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How and where is the basic heart rate set?
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The basic heart rate is set by the fastest pacemaker cell in the sinus node
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Describe 2 different physiological mechanisms to regulate capillary blood flow.
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a. Neural control using muscles around capillaries: precapillary sphincters
b. Local control by metabolic products such as increase in CO2 and decrease in O2 |
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Describe the Frank-Starling mechanism.
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The Frank-Starling mechanism describes an increase in mechanical work by the ventricle
that is caused by an increase in end-diastolic volume or venous filling pressure. |
