Endocrine System and Blood
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The endocrine system is:
the second great control system
The endocrine system interacts with the nervous system to:
coordinate and integrate the activity of body cells.
Define endocrine gland
Ductless glands that release hormones into surrounding tissue fluid.
What organ has both neural and endocrine functions?
Chemical substances secreted by cells into the extracellular fluids that regulate the metabolic function of other cells in the body.
What are the two types of chemical composition of hormones, which is most common?
- Amino acid - most common
Hormones circulate to all tissues but a given hormone influences the activity of only certain cells referred to as target cells. What must these cells contain in order for a hormone to influence its activity?
Specific protein receptors on its plasma membrane or in its interior to which the hormone can bind.
Will a given hormone have the same effect on all of its target cells?
Which type of hormones must communicate with their target cells via a second messenger and why?
Amino acid based. Because they are water soluable and can't penetrate the plasma membrane.
Although there are a few exceptions, blood levels of most hormones are controlled by what type of feedback system?
Hormones are synthesized and released in responses to what 3 stimuli? Give an example of each.
Humoral - Ca2+ in blood decreases, secrete PTH; insulin WRT to glucose levels.
Neural - Sympathetic nervous system tells adrenal medulla to secrete catecholamines
Hormonal - Hypothalamic-pituitary target endocrine organ
Where is the pituitary gland located?
What are the two lobes of the pituitary gland and what type of tissue is each composed of?
- Anterior (adenohypophysis) is glandular
- Posterior (neurohypophysis) is neural
Where are the posterior pituitary hormones synthesized and where are they stored?
The are synthesized in the hypothalamic neurons and stored in the axon terminals.
What stimulus causes posterior pituitary hormones to be released into the bloodstream?
Released when the hypothalamic neurons fire.
How does the hypothalamus regulate the secretion of anterior pituitary hormones?
By secreting releasing and inhibiting hormones.
What are the six hormones secreted by the anterior pituitary?
- Growth Hormone (GH)
- Thyroid Stimulating Hormone (TSH)
- Adrenocorticotropic Hormone (ACTH)
- Follicle Stimulating Hormone (FSH)
- Luteinizing Hormone (LH)
- Prolactin (PRL)
What is a tropic hormone?
Hormones that regulate the secretory action of other endocrine glands.
Which anterior pituitary hormones are tropic?
- Thyroid Stimulating Hormone (TSH)
- Adrenocorticotropic Hormone (ACTH)
- Follicle Stimulating Hormone (FSH)
- Luteinizing Hormone (LH)
What is the primary function of growth hormone (GH)?
Stimulates most body cells to increase in size and divide.
What substance is secreted in response to GH that mediates its effect?
Mediated indirectly by insulin-like growth factors (IGFs)
How is GH release regulated by the hypothalamus?
- Growth hormone releasing hormone (GHRH)
- Growth hormone inhibiting hormone (GHRH)
What triggers the release of Growth hormone releasing hormone (GHRH) and Growth hormone inhibiting hormone (GHRH)?
- GHRH is triggered by low blood levels of GH, hypoglycemia, exercise and stress.
- GHIH is triggered by feedback of GH and IGFs.
GH secretion has a daily cycle with peak levels ________________ . GH secretion peaks during _____________ and then declines with age.
Hypersecretion of GH after epiphyseal plate closure is called:
Acromegaly is a disorder evidenced by overgrowth of what structures?
Overgrowth of bones of hands, feet, face
What is the most common cause of acromegaly?
Tumor on anterior pituitary
What is the function of thyroid stimulating hormone (TSH)?
Stimulates normal development and secretory activity of the thyroid gland.
What triggers TSH release, what inhibits it?
- Triggered by hypothalamic hormone thyrotropin-releasing hormone (TRH)
- Inhibited by rising blood levels of thyroid hormones.
What is the function of adrenocorticotropic hormone (ACTH)?
Stimulates the adrenal cortex to release corticosteroids to help the body resist stressors.
What triggers ACTH release?
Triggered by hypothalamic hormone corticotropin-releasing hormone (CRH)
What can alter the daily rhythm of ACTH's trigger?
Can be altered by fever, hypoglycemia, and other stress.
What are the two gonadotropins and what is the primary function of each?
- FSH - egg and sperm production
- LH - production of gonadal hormones (testosterone and estrogen)
How are the gonadotropins triggered and suppressed?
- Triggered by hypothalamic hormone gonadotropin releasing hormone (GnRH)
- Suppressed by gonadal hormones (feedback)
What is the function of prolactin (PRL)?
Stimulates milk production
What regulates PRL?
Controlled by inhibitory hypothalamic prolactin inhibiting hormone (PIH)
A rise in blood levels of what other hormone results in a surge of prolactin release towards the end of pregnancy?
What are the two posterior pituitary hormones and what stimulates their release?
- Antidiuretic Hormone (ADH)
- Stimulated by the firing of hypothalamic neurons
What are the two primary functions of oxytocin?
- Uterine contractions
- Milk letdown
What kind of feedback mechanism are the functions of oxytocin?
Oxytocin drugs are utilized to induce ____________ and stop ______________ .
- post partum bleeding
What is the primary effect of antidiuretic hormone (ADH)?
Maintain water balance by inhibiting urine production.
_______________ in the hypothalmus monitor solute concentrations in the blood. If the concentration is too high, this indicates there is _______________ water in the blood stream. This results in ADH ______________ . ADH then causes _____________ to reabsorb more water from forming urine, re-establishing water balance in the bloodstream.
- kidney tubules
Alcohol _________ ADH release.
Thyroid hormone (TH) is the body's major metabolic hormone. What is its primary function?
Increases metabolic rate and body heat production.
The thyroid gland is unique in its ability to store hormone (it is actually the hormone precursor) extracellulary. Where does it store this hormone and what is the material that fills this storage site called?
It's stored as collid in follicles.
The thyroid gland secretes two forms of TH. It secretes more of ___ but most of this is converted to the more active form ____ in the tissues.
What is the leading cause of hypothyroidism globally? Why do these people have a goiter?
- Lack of iodine in diet
- Because the follicle cells are full of colloid but cannot iodinate it to produce TH
The most common cause of ______________ is Grave's disease which is a(n) _________ disease in which the antibodies produced mimic _________ which stimulates ____ release. These individuals usually develop __________ , a bulging of the eyeballs which is caused by ______________ .
- inflammed orbital tissues
What are the three ways that parathyroid hormone (PTH) increases blood calcium?
- Stimulates osteoclasts to digest bone matrix
- Enhances reabsorption of Ca2+ by the kidneys
- Promotes activation of vitamin D by the kidneys
All adrenal hormones help us cope with _____________
What are the two regions of the adrenal gland and what type of tissue comprises each?
- Adrenal medulla - nervous tissue
- Adrenal cortex - glandular tissue
What is the predominant mineralcorticoid and what layer of the adrenal cortex secretes it?
Aldosterone from the zona glomerulosa
What does aldosterone (and all mineralcorticoids) regulate? By what mechanism does the regulation occur?
Regulates electrolytes by stimulating Na+ reabsorption and water retention by the kidney tubules.
What is sodium (Na+) so important for overall body homeostatis?
It's the most abundant cation in extracellular fluid (ECF). The amount of Na+ determines the volume of ECF, blood volume, blood pressure and levels of other ions.
What stimulates and inhibits aldosterone secretion?
- Stimulated by decreasing blood volume and blood pressure
- Inhibited by increasing blood volume and blood pressure
What is the function of glucocorticoids?
Influences the metabolism of most body cells and help resist stressors
Which is the most significant glucocorticoid and what layer of the adrenal cortex secretes it?
Cortisol from the zona fasciculata
How is cortisol secretion regulated?
By negative feedback to hypothalamus (CRH) and anterior pituitary (ACTH)
What disrupts the body's normal daily rhythm of cortisol secretion?
In order to deal with stress, cortisol, via multiple metabolic effects, causes an increase in blood levels of glucose, fatty acids and amino acids. How and why do these metabolic effect occur?
Stored proteins are broken down to amino acids, carbohydrates are broken down to glucose and adipose is broken down to fatty acids to provide the building blocks for tissue repair or for making enzymes to be used in metabolic processes.
What additional action of cortisol is synergistic with the actions of the sympathetic nervous system? How does this action help the body deal with stress?
- Enhances vasoconstrictive effect.
- Rise in blood pressure to ensure delivery of nutrients to cells.
What "syndrome" is caused by hypersecretion of cortisol? What is usually the cause of this disorder? What are the "signs" of this "syndrome"?
- Cushing's Syndrome
- ACTH releasing tumor of the pituitary, lungs, pancreas, kidneys or adrenal cortex
- Signs are moon face and buffalo hump, increased blood glucose, increased blood pressure, edema, enhanced anti-inflammatory effects, suppressed immune system, loss in muscle and bone protein
What region of the adrenal gland is stimulated by the sympathetic nervous system in situations of acute stress?
What two hormones are released in response to acute stress situations?
Epinephrine and Norepinephrine
What are the six actions of Epinephrine and Norepinephrine that help the body deal with acute stress?
- Increased metabolic rate
- Increased blood glucose
- Blood vessels constrict (blood presssure goes up)
- Increased heart rate
- Blood diverted to brain, heart, skeletal muscles
- Dilation of bronchioles
All of the adrenal gland hormones are secreted in response to stress. However, there is a difference in the type of stress that results in release of hormones from the adrenal cortex vs. the adrenal medulla? What is this difference?
- Adrenal cortex is for chronic stress
- Adrenal medulla is for acute stress
What type of tumor of the adrenal gland results in hypersecretion of catecholamines?
What are the two hormones secreted by the pancreas and which type of cells secrete each?
- Glucagon - alpha cells
- Insulin - beta cells
Glucagon promotes metabolic activites that cause a(n) _________ in blood _________ levels and insulin promotes metabolic activities that cause a(n) __________ in blood _______ levels.
After what activity is insulin secretion stimulated?
Hyposecretion or hypoactivity of insulin is called __________ .
What is the predominate metabolic effect of diabetes mellitus? What are the three cardinal "signs" of diabetes mellitus?
- Excessive thirst (polydipsia)
- Excessive urination (polyuria)
- Excessive hunger (polyphagia)
What is the life threatening process that can occur during acute diabetic hyperglycemic crisis? What fatty acid metabolites causes this? Why is there an increase in these metabolites in the blood?
Fats are mobilized, ketones increase and spill into urine, because they are negatively charged they carry out Na+ and K+ with the urine. Causes vomiting, lowers blood pH (ketoacidosis), disrupts heart activity and oxygen transport, severe depression of nervous system which leads to coma and death.
Type I DM ( _________ onset) is caused by _______________ so that those with this disorder lack ___________ which must be administered to prevent ___________
- destroyed beta cells
Type II ( ______ onset) constitutes ___ % of DM cases. These individuals can produce insulin but ______________ . Those with this disorder are almost always ________ and _______ .
- receptors are unable to respond
- over weight
What are the long term complications of DM? What causes these complications? Which type of diabetics are at risk for these complications?
- Cardiovascular (stroke, heart disease, renal failure, amputations, blindness) and neurological (neuopathy, incontinency, impotence)
The gonads produce steroid sex hormones. The ovaries produce _________ and _________ and the testes produce __________ .
The thymus is felt to be involved in normal development of the ________ response. Is the thymus a prominate functioning gland in adults?
What hormonal changes contributes to old people wearing sweaters in the summer?
TH declines which lowers the basal metabolic rate
What are the three functions of blood?
Blood plasma is composed mostly of ________ . The main protein carried in blood plasma is ________ .
What are the three types of formed blood elements? Which is the only type that are complete cells?
- -Erythrocytes (RBCs)
- -Leukocytes (WBCs) (complete cell with nucleus)
What is the function of the erythrocytes? What are the three structural characteristics that contribute to this function?
- Gas transport
- - Biconcave shape
- - >97% hemoglobin
- - No mitochondria
What are the components of hemoglobin's structure?
- 2 alpha and 2 beta chains of protein globin
- red heme
What is the pigment in hemoglobin that carries oxygen?
What is the element in this hemoglobin pigment that oxygen attaches to?
How many oxygens are carried by each hemoglobin molecule?
What cells give rise to all formed elements and where are they located?
- Red bone marrow
A blood count of which RBC precursor can be utilized to provide an estimate of the rate of RBC formation?
What hormone serves as the stimulus for erythropoiesis? Where is it produced? What promotes the synthesis and release of this hormone?
What are the three dietary requirements for normal erythropoiesis?
- Vitamin B12 and folic acid
Where are old and fragile erythrocytes engulfed? What is the ultimate fate of the heme pigment of hemoglobin after RBCs are destroyed?
- In the spleen
- Heme degraded to yellow - bilirubin (bile)
What is anemia? What are three general causes of anemia?
- Blood has low oxygen carrying capacity
- - Insufficient erythrocytes
- - Low hemoglobin content
- - Abnormal hemoglobin
What is the main cause of anemia due to insufficient erythrocytes?
Bleeding from what general location is a frequent cause of the chronic form of hemorrhagic anemia? What nutritional abnormality results that exacerbates this condition?
- GI bleed/ulcer
- Iron deficiency
Pernicious anemia is a(n) ___________ disease, most common in the _______, which is caused by deficiency of ____________ due to lack of ______________ , normally produced by the stomach mucosa and needed for _____________ .
- vitamin B12
- intrinsic factor
- absorption of B12
Sickle-cell anemia, most prevalent in those of ______ ancestry, is a genetic abnormality that results in the production of abnormal _________ . RBCs become _________ in low oxygen situations which causes RBCs to rupture and dam up vessels causing _______ and ___________ (acute sickle-cell crisis).
- hemoglobin (globin chains)
- sickle shaped
- shortness of breath
What is polycythemia? What causes secondary polycythemia?
- Excess of RBCs that increase blood viscosity
- high altitude, lung issues
What is the function of the leukocytes (WBCs)?
Defense against disease
What are the three types of granulocytes?
What are the most numerous granulocytes? Why are they called "polys"?
- They are called polymorpuhonuclear leukocytes (PMNs)
Neutrophils are the body's "________ slayers" which they slay via __________ . As such, their numbers in the blood _______ during ___________ infections.
- acute bacterial
Which granulocytes play a role in allergies and asthma?
What are the two types of agranulocytes? Which are most numerous?
- Lymphocytes - more numerous
Which of the WBCs plays a crucial role in immunity?
Which are the largest leukocytes, which differentiate into macrophages and are actively phagocytic?
Finding an increased number of what immature form of granulocytes (particularly neutrophils) in the blood can be indicative of an active inflammatory or infections process?
Leukemias are a group of _______ conditions involving WBCs where abnormal leukocytes _________________ totally occupying the bone marrow and crowding out ______________ .
- are members of a single clone (remain undifferentiated and divide out of control)
- normal blood cells
________ leukemia is the more serious form affecting children and _______ leukemia involves more mature cells and is prevalent in _________
Platelets are cytoplasmic fragments of:
What is the function of platelets?
To form a temporary platelet plug that helps seal breaks in blood vessels.
What is hemostasis and what are its three steps?
- A series of reactions for stoppage of bleeding
- - vascular spasm
- - platelet plug formation
- - coagulation
What is coagulation?
What are the two pathways in phase 1 of coagulation that involve a cascade of chemical reactions to form prothombin activator? What is the difference between the two pathways that gives them their names? Which pathway is more commonly used?
- Intrinsic - triggered by negatively charged surfaces, uses factors present within the blood
- Extrinsic - triggered by exposure to tissue factor, found in tissues underneath the damaged endothelium
Where are clotting factors in phase 1 synthesized and what vitamin is necessary for synthesis of four of these?
What occurs during coagulation phase 2?
Prothrombin activator catalyzes the transformation of prothrombin to the active enzyme thrombin.
What occurs during coagulation phase 3?
Thrombin converts soluble fibrinogin to fibrin ("the clot")
What is released by endothelial cells in presence of clot that converts plasminogen to plasmin, a fibrin-digesting enzyme? In what disorders might this substance be administered acutely in the emergency room?
- Tissue plasminogen activator (tPA)
- Stroke and heart attack
What is a thrombus? What is an embolus?
- Thrombus is a clot that develops and persists in an unbroken blood vessel
- Embolus is a thrombus, or part of a thrombus, that breaks away and floats freely in the blood stream.
What are three causes of bleeding disorders? What are the hemophilias caused by?
- -Impaired liver function
- Absence of single clotting factor
Blood is tested and categorized into blood types since:
Transfusions of incompatible blood can be fatal.
Antigens of which two blood groups can cause vigorous transfusion reactions?
Of the ABO blood groups, which is the univeral donor? Why?
O, doesn't have A or B antigen
Of the ABO blood groups, which group is the universal recipient? Why?
AB, doesn't have antibodies to either A or B antigen
What is the most devastating problem in a transfusion reaction? What causes this?
- Acute renal failure
- Hemoglobin is toxic to kidneys
What are two common solutions used to restore blood volume?
- Normal saline
- Ringer's lactate
What are PT and PTT blood tests used to assess?
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