- The general function of the endocrine system is to_______________body systems, in conjunction with the nervous system.
- Which system works faster to integrate or maintain __________________ ?
- Which system has a more lasting effect?
- ____________ GLANDs secrete hormones directly into the _____________; (______________)
- What type of gland is a sweat gland? Duct or ductless?
- ______________ are powerful substances secreted by an ____________ gland into
the bloodstream, that affects the function of another cell or "___________ cell".
- How does a hormone know its target?
HORMONES
- General Characteristics:
- needed in very ______________ amounts (potent);
- produce __________________ effects in the cells they _____________;
- regulate ______________ processes (maintain ___________________ );
- are regulated
by _______________________ mechanisms
- Secretory Stimulation
Methods
- Hormonal Interactions
- Permissive effect
- a second hormone, strengthens the effects of the first
- thyroid strengthens epinephrine's effect upon lipolysis
- Synergistic effect
- two hormones acting together for greater effect
- estrogen & LH are both needed for oocyte production
- Antagonistic effects
- two hormones with opposite effects
- insulin promotes glycogen formation & glucagon stimulates glycogen breakdown
- Chemistry
of Hormones
- Steroid Hormones
- derived from cholesterol
- sex hormones
- adrenal cortex hormones
- Amino Acid based hormones
- amines
- proteins
- peptides
- glycoproteins
- most hormones
- Eicosanoids - biologically active lipids with local hormone-like activity
- Leukotrienes
- prostaglandins
- Action Of a Steroid
Hormones
- The steroid hormone crosses the ____ ___________
- Next the hormone combines with a ____________ in nucleus
- Followed by the activation of DNA transcription and the synthesis of ________.
- mRNA enters cytoplasm to direct synthesis of _________ on a ______________.
- Action of a Nonsteroid Hormones (protein)
- First Messenger
- A hormone binds to a _____________ on the _______ _____________.
- The receptor combines with a inactivate ____ protein which is activated by ____.
- The activated G protein then activates _____________
- Adenylate cyclase causes _______ to be converted to _________.
- Second Messenger
- Target Cell Specificity
- Hormones circulate to all tissues but only activate________ cells
- Target cells must have specific__________ to which the hormone binds
- These receptors may be intracellular or located on the plasma membrane
- Examples of hormone activity
- ACTH receptors are only found on certain cells of the __________ _________
- Thyroxin receptors are found on nearly _______ cells of the body
- Target Cell Activation
- Target cell activation depends on three factors
- Blood _________ of the hormone
- Relative number of __________ on the target cell
- The ________ of those receptors for the hormone
- _____-regulation - target cells form more receptors in response to hormone
- _______-regulation - target cells lose receptors in response to the hormone
- Hormone Concentrations in the Blood
- Hormones circulate in the blood in two forms - free or bound
- Steroids and thyroid hormone are attached to plasma proteins
- All others are unencumbered
- Concentrations of circulating hormone reflect:
- Rate of release
- Speed of inactivation and removal from the body
- Hormones are removed from the blood by:
- _____________ ____________
- The _____________
- ___________ enzyme systems
- Blood levels of hormones:
- Are controlled by ___________ _____________ systems
- Vary only within a ___________ desirable range
- Blocking Hormone Receptors
- Synthetic drugs may block receptors for naturally occurring hormones
- Normally, progesterone levels drop once/month leading to menstruation. Progesterone levels are maintained when a woman becomes pregnant.
- RU486 (mifepristone) binds to the receptors for progesterone preventing progesterone from sustaining the endometrium in a pregnant woman
- brings on menstrual cycle
- used to induce abortion
- Nervous System Modulation
- The __________ system modifies the stimulation of endocrine glands and their negative feedback mechanisms
- The nervous system can ___________ normal endocrine controls
- For example, control of blood glucose levels
- Normally the endocrine system maintains blood glucose
- Under _________, the body needs more glucose
- The ____________ and the ______________ nervous system are activated to supply ample glucose
Hypothalamus - PituitaryConnection
- Posterior Pituitary Lobe
- The posterior lobe is a downgrowth of hypothalamic neural tissue
- Has a neural connection with the hypothalamus (hypothalamic-hypophyseal tract)
- Nuclei of the hypothalamus synthesize___________ and ____________ ___________ (ADH)
- These hormones are transported to the ____________ pituitary
- Why are the hormones of the hypothalamus called neurohormones?
- Anterior Pituitary Lobe
- There is no direct neural contact with the hypothalamus
- Why is the anterior lobe of the pituitary much larger than the posterior lobe?
- Releasing and Inhibiting hormones of the hypothalamus are released into the ___________ _______ _______ to be transported to the anterior pituitary.
- The six hormones of the adenohypophysis:
- Are abbreviated as GH, TSH, ACTH, FSH, LH, and PRL
- Most regulate the activity of other ______________ glands
- Hypothalamic Hormones
- The hypothalamus sends a chemical stimulus to the anterior pituitary
- Releasing hormones stimulate the synthesis and release of hormones
- Inhibiting hormones shut off the synthesis and release of hormones
- Name the 5 releasing hormones that the hypothalamus releases into the anterior pituitary to stimulate the release of anterior pituitary hormones.
- Name the 2 hormones
from the hypothalamus that are released at axon terminals into the capillary bed of the posterior pituitary.
- When you body's nervous system comes under stress how does the hypothalamus help you respond?
ENDOCRINE GLANDS - endocrine
glands. The following glands:(handout)
- The ANTERIOR PITUITARY
GLAND secretes 6 different hormones:
- Human Growth Hormone (HGH)
- Controls _______ of the body by _________ the bone, muscle and adipose tissue
- stimulates increase in size and rate of body cells
- enhances movement of amino acids through membranes
- promotes growth of long bones
- uses adipose for cellular fuel
- Pituitary Dwarfism = ______________ of GH during growth years.
- --slow bone growth & closing of ___________ ________ before normal height
- --Treatment = oral GH therapy.
- Pituitary giantism = ________________of GH during growth years.
- Acromegaly = _____________________ of GH during adulthood.
- --Bones of hands, feet, cheeks, and jaw thicken
- Prolactin (PRL)
- sustains ______ production after birth
- targets the ______________ glands.
- secretion inhibited by prolactin inhibiting hormone of the _____________
- Thyroid stimulating hormone (TSH)-
- controls the secretion of hormones by the ______________ gland;
- controlled by thyrotropin-________ hormone
- Rising blood levels of thyroid hormones act on the pituitary and hypothalamus to block the release of TSH
- Adrenocorticotropic Hormone (ACTH)
- Stimulates secretion of corticosteroids hormones of _________ _________
- Controlled by ____________-releasing hormone in a daily rhythm
- Internal and external factors such as fever, hypoglycemia, and stressors can trigger the release of CRH
Follicle Stimulating Hormone (FSH) - response depends upon sex:
- stimulates secretion of estrogen & development of egg-containing _________ in _________
- stimulates production of sperm cells in the ___________
- controlled by ________________-releasing hormone
Luteinizing Hormone (LH)
- promotes secretions of male sex hormones & stimulates release of ______ from ovary
- promotes ___________ of long bones
- controlled by gonadotropin-releasing hormone from the ______________
- The POSTERIOR PITUITARY
GLAND
- Anti-Diuretic Hormone (ADH) vasopressin:
- Causes ___________ to reduce water excretion
- In high concentration, raises ______ ________
- Controlled
by _________________ in response to changes in _______ water concentration and ______ volume
- Diabetes insipidus = _________ secretion of ADH
- Alcohol causes ___________ scecretion of ADH.
- One method used to control blood pressure is to use ____________ which will reduce ______ _______.
- Why is ADH called vasopressin?
- Oxytocin (OT)
- Targets the __________ and the __________ _________.
- Stimulates uterine ________________ & mammary glands to release __________
- THYROID GLAND
- Largest endocrine gland, located in the anterior neck, consists of two lateral lobes connected by a median tissue mass called the isthmus
- Lumen of the follicles is filled with the colloidal glycoprotein,________________, percursor of the thyroid hormone.
- Other endocrine cells, parafollicular cells, produce the hormone ______________
- Thyroid hormone - the body's major _____________ hormone
- Consists of two closely related iodine-containing compounds - __________________________________________
- TH is concerned with:
- Glucose oxidation
- Increasing metabolic rate
- Heat production
- TH plays a role in:
- Maintaining blood pressure
- Regulating tissue growth
- Developing skeletal and nervous systems
- Maturation and reproductive capabilities
- Regulation is by negative feedback
- Hypothalamic thyrotropin-releasing hormone (TRH) can overcome the negative feedback
- Disorders
- Cretinism = ____________of T3/T4 during fetal life and infancy.
- dwarfism & mental retardation;
---prevention = newborn testing; oral thyroid therapy.
- Myxedema = __________________ during adulthood.
- edema, slow heart rate, low body temp, dry hair & skin, muscular weakness, lethargy, weight gain;
- Oral thyroid hormones reduce symptoms.
- Grave's Disease an _______________disorder that causes growth of thyroid and hypersecretion of thyroid hormones, with
no negative feedback.
- enlarged thyroid (2-3x larger); peculiar edema of the eyes (bulging);
- increased metabolic rate, heat intolerance, increased sweating, weight loss, insomnia, tremor, nervousness.
- treatment = surgical removal, use of radioisotopes to destroy some of the thyroid. and anti-thyroid drugs to block synthesis of the hormones.
- Simple Goiter
- deficiency of ____________ leads to deficiency of thyroid hormones
- gland enlarges
Calcitonin:
- release is triggered by an increase in
blood ___________ levels;
- targets bone cells (inhibits osteoclast activity) & kidney tubules (causes secretion of calcium into urine);
- Therefore, causes a ___________in blood calcium & phosphate levels to normal.
- PARATHYROID GLANDS:
- Consists of 4
small glands located posteriorly on thyroid gland;
- Produce a hormone called Parathyroid Hormone (PTH):
- release is stimulated by a ___________ in blood calcium levels;
- PTH targets bone cells to release Ca++ into blood
- Also activates vitamin ____ to absorb Ca++ from the _________.
- Stimulates the kidneys to _________ Ca++ and ______ PO4.
- PTH causes an _________ in blood Ca++ and _________ in PO4 levels to normal
- __________parathyroidism
- caused by tumor; fatigue; muscular weakness; altered mental functions;bone weakening
- _________parathyroidism
- caused by injury or removal of gland; muscle cramps; seizures; low blood calcium levels
- PTH and calcitonin together maintain the _____________ of Ca++ in the blood
- ADRENAL GLANDS
- Adrenal glands - paired, pyramid-shaped organs atop the ___________
- Structurally and functionally, they are two glands in one
- Adrenal __________ - nervous tissue that acts as part of the SNS
- Adrenal _________ - glandular tissue derived from embryonic mesoderm
- ADRENAL CORTEX
- Synthesizes and releases _________ hormones called ________________
- Different corticosteroids are produced in each of the three layers
- Zona glomerulosa - mineralocorticoids (chiefly ________________)
- Zona fasciculata - glucocorticoids (chiefly ______________)
- Zona reticularis - gonadocorticoids(chiefly ______________)
- Mineralocorticoid (aldosterone)
- Regulate the electrolyte concentrations of extracellular fluids
- Maintains Na+ balance by reducing _____________ of sodium from the body
- Stimulates reabsorption of Na+ by the kidneys
- Aldosterone secretion is stimulated by:
- Rising blood levels of ______
- Low blood ______
- Decreasing blood ______________________
- The Four Mechanisms of Aldosterone Secretion
- _________________________ - kidneys release renin, which is converted into angiotensin II that in turn stimulates aldosterone release
- Plasma concentration of ____________ and _______________ - directly influences the zona glomerulosa cells
- _________ - causes small increases of aldosterone during stress
- ________________________________ (ANP) - inhibits activity of the zona glomerulosa
- Glucocorticoids (Cortisol)
- Help the body resist ________ by:
- Keeping blood sugar levels relatively constant
- Maintaining blood volume and preventing water shift into tissue
- Cortisol provokes:
- >Gluconeogenesis (formation of glucose from ____________________ )
- Rises in blood glucose, _______ ________, and ________ _________
- Excessive levels of glucocorticoids:
- Depress cartilage and bone formation
- _________ inflammation
- __________ the immune system
- Promote changes in cardiovascular, neural, and gastrointestinal function
- Gonadocorticoids (Sex Hormones)
- Most gonadocorticoids secreted are androgens (male sex hormones), and the most important one is ______________
- Androgens contribute to:
- The onset of puberty
- The appearance of secondary sex characteristics
- Sex drive in females
- Androgens can be converted into ___________ after menopause
- hirsutism
- Adrenal Cortex Disorders
- Addison's Disease ____________ of AC hormones due to autoimmunity or disease.
- Symptoms: mental lethargy, anorexia, nausea, vomiting, weight loss, hypoglycemia, muscle weakness
- Increased K+, decreased Na+ & BP, dehydration
- skin hyperpigmentation
- Cushing's Syndrome = ______________of AC hormones due to pituitary tumor or steroid administration.
- Symptoms:redistribution of fat, thin limbs due to wasting of muscles
- "moon face", "buffalo hump", "beer belly", stretch marks, bruises,
- poor wound healing, hyperglycemia, osteoporosis
- hypertension, susceptibility to infection
- resistance to stress, mood swings
- Usual cause: administration of steroids for transplant patients, asthma, etc.
- ADRENAL
MEDULLA:
- Made up of chromaffin cells that secrete epinephrine and norepinephrine
- Secretion of these hormones causes:
- Blood glucose levels to __________
- Blood vessels to ____________
- The heart to beat _______________
- Blood to be diverted to the brain, heart, and skeletal muscle
- Tumor may cause a disorder
- ________________ is the more potent stimulator of the heart and metabolic activities
- __________________is more influential on peripheral vasoconstriction and blood pressure
- PANCREAS - Islets of Langerhans:
- A triangular gland, which has both _______________ & ___________________cells, located behind the stomach
- Acinar cells produce an enzyme-rich juice used for digestion (exocrine product)
- Pancreatic islets (________________________) produce hormones (endocrine products)
- Glucagon - hyperglycemic agent
- A 29-amino-acid polypeptide hormone that is a potent ___________________ agent
- Its major target is the ___________, where it promotes:
- Glycogenolysis - the breakdown of ________________ to glucose
- Gluconeogenesis - synthesis of glucose from _____________ and ____________________
- Release of glucose to the ________ from liver cells
- Insulin - hypoglycemic agent
- A 51-amino-acid protein consisting of two amino acid chains linked by disulfide bonds
- Insulin:
- Effects of Insulin Binding
- The insulin receptor is a tyrosine kinase enzyme
- After glucose enters a cell, insulin binding triggers enzymatic activity that:
- Catalyzes the oxidation of glucose for _______ production
- Polymerizes glucose to form ______________
- Converts glucose to _______ (particularly in adipose tissue)
- Diabetes Mellitus (DM) - hyperglycemic
- Results from hyposecretion or hypoactivity of insulin
- The three cardinal signs of DM are:
- _____________ - huge urine output
- _____________ - excessive thirst
- ______________ - excessive hunger and food consumption
- Type I /IDDM (10%): absolute insulin deficiency
- Patients < 20 years
- ? autoimmune disorder where B-cells are destroyed
- insulin administration
- Cells can't use glucose so fat is broken down, releasing ketone bodies, causing ketoacidosis, lowering blood pH, causing death.
- Atherosclerosis, CV disease, IHD, PVD, gangrene
- Complications = blindness due to cataracts (lens) and retinal vascular disease; renal failure
- Type II/NIDDM (90%)
- patients > 40 years
- overweight
- Hypertensive
- Smokers
- Problem is usually with receptors on target cells;
- May be controlled by diet, exercise, and weight loss in about 1/3 of the cases.
- Hyperinsulinism - excessive _________ secretion, resulting in hypoglycemia.
- Pineal Gland
- Is attached to the __________ of the brain stem
- Secretes a hormone called __________
- Production is ___________ by daylight (circadian rhythm)
- Affects moods, emotions, etc.
- May control onset of puberty
- Helps regulate female reproductive cycle
- Seasonal Affective Disorder & Jet Lag
- Thymus Gland
- Is located in the mediastinum region behind sternum
- Produces a hormone called _________ that affects the maturation of lymphocytes (_______)
- Plays an important role in __________ system and __________
___________ in size as we age.
- Match hormones with gland
Other Hormone-Producing Structures
- Heart - produces _____________________________ (ANP), which reduces blood pressure, blood volume, and blood sodium concentration
- Gastrointestinal tract - enteroendocrine cells release local-acting ___________ hormones
- Placenta - releases hormones that influence the course of ______________
- Kidneys - secrete _______________, which signals the production of red blood cells
- Skin - produces cholecalciferol, the precursor of __________________
- Adipose tissue - releases________, which is involved in the sensation of satiety, and stimulates increased energy expenditure
- The hormone ghrelin produced by the stomach apposes leptin and causes hunger and slows down metabolism during weight loss.
Hormone -Like substances
- Not secreted from a distinct organ
- Local hormones synthesized and secreted by the tissues they act on.
- Prostaglandins (PGE2:
- Released from injured cells.
- Initiates the inflammation response, stimulates pain receptors and blood coagulation.
- Helps stimulate urterine contractions and ovulation
- Aspirin and other analgesic effects?
- Endorphins and Enkephalins
- Bind to the same receptors as morphine. Reduces?
- Secretion by the nerves due to exercise and stress.
Developmental Aspects
- Exposure to pesticides, industrial chemicals, arsenic, dioxin, and soil and water pollutants disrupts hormone function
- Sex hormones, thyroid hormone, and glucocorticoids are vulnerable to the effects of pollutants
- Interference with glucocorticoids may help explain high cancer rates in certain areas
- Ovaries undergo significant changes with age and become unresponsive to gonadotropins
- Female hormone production declines, the ability to bear children ends, and problems associated with estrogen deficiency (e.g., osteoporosis) begin to occur
- Testosterone also diminishes with age, but effect is not usually seen until very old age
- GH levels decline with age and this accounts for muscle atrophy with age
- TH declines with age, causing lower basal metabolic rates
- PTH levels remain fairly constant with age, and lack of estrogen in women makes them more vulnerable to bone-demineralizing effects of PTH
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