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______ is the means whereby neighboring cells in direct contact with each other, communicate by the exchange of ions and molecules, through gap junctions in the cell membrane; local type of communication acting over extremely small distances
Name 4 types of Communication
- 1. Direct Communication
- 2. Paracrine Communication
- 3. Synaptic Communication
- 4. Endocrine Communication
______ communication also occurs over small distances, but uses chemical messengers that are used to carry information from cell to cell within the same tissue; the concentrations of the the chemical messengers are so low that they do not affect neighboring tissues
What is it called when a specialized cell, the neuron, releases a neurotransmitter ver close to the target cell (the effector) at the synapse? effects are usually short lived
A ____ is defined as a chemical messenger released by a tissue which is carried in the circulation to reach specific target cells in other tissues around the body.
What are the 3 categories that hormones are classified into based on their structure?
- 1.Those derived from amino acids
- 2. Peptide hormones
- 3. Those derived from lipids
What are some hormones derived from amino acids? these are from the former _________ of the pituitary.
Epinephrine, norepinephrine, thyroid hormones, melanin; intermediate lobe
Other hormones within the peptide hormone group that form from an amino acid chain with a carbohydrate attached?
Glycoprotein based hormones
Name 2 Glycoprotein based hormones
Follicle stimulating hormone (FSH) and Luteinizing hormone (LH)
______ communication involves the release of hormones, produced by specialized endocrine cells, into the circulatroy system where they are carried to the target cells, tissues, or organs. The target cells, tissues or organs have specialized receptor sites to which the hormone must bind before it exerts its effects.
____ transmission of impulse where the membranes are fused to one another
Peptide hormones are formed from peptides or longer chains of amino acids. THose formed from short chains include:
Antidiuretic hormone(ADH) and Oxytocin from the posterior pituitary.
Peptide hormones have longer chains and are classified as small proteins are:
Growth Hormone (GH) and Prolactin
What is the Antidiuretic Hormone (ADH) AKA
Hormones derived from lipids belong to one of two groups, those similar in structure to cholesterol are known as _____ hormones whereas those derived from the essential fatty acid arachidonic acid are called _____.
- Steroid hormones
Name the 4 steroid hormones and what they are released by
- 1. Estrogens- adrenal gland
- 2. Testosterones- adrenal gland
- 3. Glucocorticoid-adrenal gland
- 4. Calcitriol- kidney
____hormones differ from other hormones in that they are transported in the blood bound to _______ rather than free molecules; this causes them to remain in circulation longer than other hormones
Steroid; carrier proteins
______ act as improtant paracrine molecules, coordinating cellular activity and enzyme reactions in extracellular fluid.
Name the 3 Eicosanoids
- 1. Prostaglandins
- 2. Thromboxanes
- 3. Leukotriens
The majority of hormones in the body are controlled by a _______ mechanism.
THe stimulus that triggers the secretion of hormones is usually one of the following:
- 1. Change in the extracellular fluid
- 2. secretion or removal of another hormone
- 3. release of a neurotransmitter that affects the endocrine gland
Blood levels of most hormones operate through a negative feedback mechanism maintaining _____
As blood glucose levels ___ following a meal, the production of ____ is stimulated and the blood glucose results in a __ in the secretion of insulin from the ____.
rise, insulin, fall, pancreas
2 organs known as "sweet breads"
- 1. hypothalamus
- 2. pancreas
The _____ is located beneath the thalamus of the brain and plays a critical role in controlling the release of many of the hormones within the body.
This secrets regulatory hormones that control the hormonal activity of the anterior pituitary, so affecting the activity of the thyroid gland, the cortex of adrenal gland and the reproductive organs.
The hypothalamus has _____ nervous control over the hormones secreted by the _____ of the adrenal glands, in addition to acting as an endocrine organ itself, releasing hormones into circulation via the _________.
autonomic; medulla; posterior pituitary gland
The ______ and ________ work hand in hand to regulate many of the organs of the body and thus are often viewed as one even though they are not.
Hypothalamus and pituitary glands
The pituitary gland or hypophysis can be considered into two parts, what are they?
- -Posterior pituitary, posterior lobe, pars nervosa or neurohypophysis
- - Anterior pituitary, Anterior lobe, Adenohypophysis
For years their was an _______ of the pituitary identified seperately as one of the three lobes. The most recent nomenclature includes this in with the ______.
Intermediate lobe; anterior lobe
What are the 3 divisions of the Adenohypophysis(anterior lobe or anterior pituitary)
- 1. Pars tuberalis
- 2. Pars Intermedia
- 3. Pars distalis
formed from a structure called Rathkes Pouch, a structure derived from the mucous membranes of the embryonic pharynx.
Originated from the embryonic brain, and in the adult, the posterior lobe is still connected to the brain by means of the pituitary stalk. This allows for the production of posterior pituitary hormones to be produced in the hypothalamus and be transported via nerves to the posterior lobe to be stored and later used as needed.
The posterior pituitary acts as a storage site for two hormones?
These are both synthesized in the ______ by specialized secretory neurons and are stored in the posterior pituitary prior to release.
- 1. Oxytocin
- 2. Antidiuretic hormone or Vasopressin
- ; hypothalamus
____ has effects on the kidneys, causing an increase in the absorption of water by the tubules. this reduces the volume of urine and increases the water retention and volume of blood.
Antidiuretic hormone (ADH)
causes contraction of the smooth muscle of the uterus during labor and stimulates milk production of "let down" at lactation.
is composed of epithelial cells and connective tissue separated by sinusoids of blood. This area has six types of cells that can be seen and differentiated.
precursor to cells that produce the hormones of the anterior lobe.
are separated on the basis of their staining properties which can be correlated to the hormones that they produce.
the 2 types of chromophils
- 1. Acidophils (red)
- 2. Basophils (blue)
- 1. Somatotrophs produce STH
- 2. Lactotrophs produce Prolactin
- 1. FSH gonadotrophs produce FSH
- 2. LH gonadotrophs produce LH
- 3. Thyrotrophs produce TSH
- 4. Corticotrophs produce ACTH
a series of veins that carry blood from the pituitary stalk and the brain to the adenohypophysis of the pituitary gland. THese veins break up into small capillaries and actually account for the control of the hormones released by the adenohypophysis
Hypothalmic-hypophyseal Portal system
Somatotropic hormone, Somatotropin, Growth Hormone
Adrenocorticotropin, adrenocorticotropic hormone, corticotropin
Thyrotropin, thyroid stimulating hormone
Follicle stimulating hormone
Lutenizing hormone, Insterstitial cell stimulating hormone (ICSH)
Luteotropic hormone, luteotropin, lactogenic hormone, prolactin
_____ or thyrotropin exerts its effect upon the thyroid gland and stimulates the production of the thyroid hormones, thyroxine (T4), Liothyronine (T3) and calcitonin (thyrocalcitonin)
Thyroid stimulating hormone
NAme the 3 thyroid hormones
Thyroxine (T4), liothyronine (T3) and calcitonin (thyrocalcitonin)
Thyroid stimulating hormone (TSH) stimulates the synthesis of ____ by thyroid gland cells and stimulated the release of thyroid hormones.
The thyroid gland consists of follicles filled wiht material called ____, the majority of which consists of a protein-iodine complex called ____. _____ _______ are present in the thyroid gland in addition to the regular follicular cells.
colloid; thyroglobulin; C cells (parafollicular cells)
The C cells produce _____ which lowers the blood level of calcium. ______ raises Ca blood level by absorbing Ca from the bone. Therefore these are _____
Calcitonin, Parathormone; antagonistic
Thyroglobulin is the parent unit for:
1. Levothyroxine Sodium (tetraiodotyrosine)- T4 Brand Name:
2. Liothyronine sodium (triiodotyrosine)- T3 Brand Name:
- Soloxine and Synthyroid
3 internal diseases that cause bilateral alopecia
- 1. Hypothyroidism
- 2. Hyperadrenocorticism
- 3. Hyperestrogenism
Thyroglobulin requires ___ as an essential part to form T3 and T4 and be biologically active.
Iodine in the blood is in the form of ____, but in the thyroid gland it is in the form of ____ or ____
iodides; Iodine or Oxidized Iodine
The oxidized form combines with ____ (aa) in the synthesis to T3 and T4.
The thyroid gland traps iodide in the ____ and oxidizes it to ____. The Iodine is then incorporated into the amino acid ___, form ______ (MIT) and ______(DIT). Subsequent coupling of these iodotyrosine form ______(triiodotyrosine) and ____(tetraodotyrosine)
colloid, iodine, tyrosine, Monoiodotyrosine and Diiodotyrosine, Liothyronine- T3 and Levothyroxine-T4
What is the Name for T3?
What is the name for T4?
___ is formed and stored in the thyroid gland and is the main secratory product of this thyroid gland.
Less than ____ of T3 is formed in the tyroid gland; the remaining T3 is formed from the _____ of T4
The primary functions of T3 and T4
- 1. control of enzymes and proteins for metabolism
- 2. maintenance of normal hair growth and skin condition
- 3. normal fetal development
Foods that are Goitrogenic (hyperthyroglobulin production)
- 1. Cabbage
- 2. Rutabagas
- 3. Turnips
4 clinical symptoms of Hypothyroidism
- 1. lethargic
- 2. Anemia
- 3. bilateral alopecia
- 4. Cold
5 Metabolic symptoms of Hypothyroidism
- 1.mental dullness
- 2. lethargy
- 3. exercise intolerance
- 4. weight gain with no increase in appetite
- 5. cold intolerance
4 clinical symptoms of Hyperthyroidism
- 1. Nervous
- 2. fatigue
- 3. hunger
- 4.weight loss
4 Dermatological symptoms of Hypothyroidism
- 1. Alopecia
- 2. Seborrhea
- 3. pyoderma
- 4. myxedema
is the most common form, occurring in over 95% of cases , and is a result of destrcution of the thyroid gland
The most common symptoms of Primary Hypothyroidism can be summarized into two areas:
Metabolic and dermatologic
Because the Hypothyroidism develops so gradually, clinical signs are not noticeable until ___ of the thyroid has been destroyed.
Hypothyroidism starts at what age of dog?
4-6 years but can be seen at 2-9 years old
Testing for Hypothyroidism; what two test are available.
Thyroxine (T4) may be useful as an initial screening test. If the T4 is in the normal range, then it is unlikely that the patient is hypothyroid. 1. RIA- Radioimmunoassay and Equilibrium Dialysis
Thyroid tumors in the cat produce excessive amounts of _____ and the cats develop the clinical syndrome hyperthyroidism. 6 signs are:
- thyroxine (T4)
- 1. tachycardia
- 2. hyperactivity
- 3. weight loss
- 4. polyphagia
- 5. polyuria
- 6. polydipsia
Some cats have ____________ a syndrome characterized by signs opposite to classic presentation for hyperthyroidism. eg depression, lethargy, and anorexia
Treatments for hyperthyroidism in cats include:
- 1. Methimazole- drug of choice comes in form of Tapazole 5 mg per os bid
- 2. Radioactive Iodine Treatment
- 3. Surgical Removal of the Glands
What is the most frequent diagnosed endocrine disorder in cats? Treatment of choice?
Hyperthyroidism; Radioiodine administration
Hyperthyroidism in the Cat
Principle: _____ are the major secretory products of the thyroid gland and important hormones at target issues
Interpretation: _____ is the most reliable test to differentiate cats with hyperthyroidism from cats with non-thyroidal diseases.
- Thyroxine (T4) and Liothyronine (T3)
- Measurement of random basal serum T4 concentrations
________ is actively concentrated in the thyroid tissue and act there to block thyroid hormone sythesis at several steps. ____ uptake as well as the release of previosly synthesized and stored hormone are ____. some scientists believe uptake _____.
Methimazole; Iodine, not prevented; is prevented
Secretion of adrenocoricotropic hormone (ACTH or adrenocortin) is regulated by ________ (CRH) from the _____.
Corticotropin releasing hormone; hypothalamus
ACTH regulates the production of glucocorticoids (____ and ______) and _________ as well as sex hormones from the _____ of the adrenal gland. These are steroid-based hormones that affect cellular _____.
cortisol and corticosterone; mineralocorticoids; cortex; metabolism
Name the 2 parts of the Adrenal Gland
- 1. Adrenal Cortex
- 2. Adrenal Medulla
Name the 4 parts of the Adrenal cortex- outer to inner
- 1. Capsule
- 2. zona glomerulosa
- 3. zona fasiculata
- 4. zona reticularis
the outermost layer thought to be responsible for the secretion of mineralocorticoids
middle layer most responsible for secretion of the glucocorticoids although the reticularis does contribute
inner layer is the zone for sex steroids although total quantity is less than 5%
Name restricted to the hormones produced by the zona fasiculata of the adrenal cortex.
Corticosteroids are applied to:
- 1. Hormones produced by the adrenal cortex (glucocorticoid/corticosteroid)
- 2. All synthetic equivalents like Dexamethasone, Prednisone, etc.
Secreted in response to the production of gonadotropin releasing hormone (GnRH) from the hypothalamus
Follicle-stimulating hormone (FSH)
FSH acts on the _______ in the female animal to stimulate its development and maturation
In the male animal, FSH promotes the maturation of ___.
LH is another hormone regulated by ____. It stimulates _____ and development of the _____ in the female.
GnRH; ovulation; corpus luteum
LH, In the male regulates production of the hormone ______ by the interstitial cells of Leydig in the testes.
In the male LH may sometimes be referred to as
Interstitial cell stimulation hormone (ICSH)
The hormone Prolactin (PRL) 1. stimulates the development of the _______ of the pregnant female animal. 2. as well as playing as active role in ____ following parturition.
mammary glands; lactation
Name the 2 hypothalamic hormones that control prolactin's secretion
- 1. Prolactin releasing factor (PRF)
- 2. Prolactin inhibiting hormone (PIH)
plays a critical role in all cellular growth. It regulates the production of proteins by cells and controls the energy used within the body.
Growth hormone (GH or somatotropin)
During times of poor food supply it will stimulate the utilization of lipid as an energy source in order that essential glucose can be conserved from the nervous system. particularly important in young growing animals
Growth Hormone (GH, Somatotropin)
GH production is regulated by what 2 hormones
- 1. growth hormone releasing hormone (GH-RH)
- 2. Hormone inhibiting hormone (GH-IH) produced by the hypothalamus
The final hormone produced by the anterior pituitary is the former intermediate lobe hormone called
melanocyte-stimulating hormone (MSH)
MSH is particularly important in the production of _____ in fish, amphibia, reptiles and many mammals although not in ____.
skin pigments; primates
The secretion of MSH is regulated by melanocyte stimulating hormone inhibiting hormone (MSH-IH) produced by the
sometimes called the "third eye"; lies in the posterior part of the third ventricle of the brain.
_____ gland contains neurons, neuroglia, and specialized secretory cells called ____.
Pineal gland; pinealocytes
the pinealocytes secrete a hormone called ____ that forms the basis for the neurotransmitter molecule known as _____.
serotonin is secreted by ____
During periods of _____ production of melatonin is ___ while during _____ its production is __.
darkness; high. daylight; low
Melatonin is linked with the timing of ______, ___ and possibly with the maintenance of _____ rhythms.
sexual maturation, estrus, maintenance of circadian rhythms
Endocrine cells called _____ produce parathyroid hormone (PTH or Parathormone) in response to falling levels of calcium ions in the blood.
PTH stimulates the secretion of ____ by the kidney: this increases the efficiency with which calcium is absorbed from the digestive tract
PTH and Calcitonin are____
Hyperparathyroidism can occur in one of 3 ways.
- 1. Neoplasia of the parathyroid gland
- 2. Secondary indirect hyperparathyroidism
- 3. Secondary direct hyperparathyroidism
can cause over production of PTH. This causes demineralization of bone and may cause the bones to weaken and fracture.
Neoplasia of the gland (abnormal growth)
can be seen in cases of chronic renal failure, resulting in Ca loss. Body attempts to maintain level of Ca by absorbing more form the bone resulting in rubbery like bones _____
Secondary indirect hyperparathyroidism; "rubber jaw"
is not frequent today but can occur when dog is fed meat only. meat is low in Ca levels for dogs so the dog adjust with over-production of PTH
Secondary nutritional hyperparathyroidism
The thyroid gland lies just below the larynx and secretes three thyroid hormones:
- 1. Thyroxine (T4)
- 2. Liothyronine (T3)
- 3. calcitonin or thyrocalcitonin
T4&T3 regulate _______ via the mitochondria and the production of ATP
Calcitonin assists with regulation of _________ in the blood and is secreted when there is an ____ in the concentration of calcium ions above the threshold level.
calcium ion concentration; increase
Opposite in its effect to PTH, it causes a fall in the calcium ion concentration by inhibiting osteoclasts activity in bone and by promoting the secretion of calcium ions by the kidney in the urine.
is also thought to be improtant in the regulaton of bone growth in young animals and in maintainign the balance of calcium ions between bitch and fetus during pregnancy.
The thymus ("sweet bread") is located in the _____________
mediastinum in the thorax
The thymus produces a hormone called _____ that promote __________ of lymphocytes. In this way it is thought to be a major contributing factor to the immune response in the young animal.
thymosins; development and maturation of lymphocytes
the walls of the atria contain endocrine cells that secrete a hormone, _________ when over stretched
atrial natriuretic peptide (ANP)
_______ reduces blood volume
Atria natriuretic peptide
The kidney secrete two hormones
calcitrol and erythropoietin
thought to have effects on muscle contraction, insulin release, and secretion of testosterone.
is released by the kidney when circulating blood oxygen levels are low. Its stimulates the bone marrow of long bones to increase the rate of production of rbc in an attempt to increase the oxygen carrying capacity of blood
The adrenal Cortex is divided into 3 layers
- 1. Zona Glomerulosa - outer layer (mineralocorticoids)
- 2. zona fasiculata- middle layer (glucocorticoids)
- 3. zona Reticularis- inner (sex hormones
The outer layer of the adrenal gland called the cortex produces more than ___ different hormones all ____ based.
From zona glomerulosa and represented by ______ contributes to the regulation of electrolytes within the body, primarly sodium and potassium.
The zona fasciculata and zona reticularis, the ________ such as ____ and _____ are secreted at times of stress. They help to spare glucose by mobilizing other sources of energy such as amino acids and lipids.
glucocorticoids; cortisol and corticosterone
______ a condition known as Cushing's disease. The adrenal cortices produces excessive amount of glucocorticoids in particular ____.
6 symptoms of Cushings
- 1. polyphagia
- 2. polydipsia
- 3. polyurea
- 4. hair loss
- 5. pot belly
- 6. thinning of skin
85-90% of all cushings disease is due to ________ with the other 10-15% being from ____
pituitary tumors; adrenal tumos
is an adrenocorticlytic drug. Causes necrosis of the zona fasiculata and zona reticularis. hard to control but safer than Vetoyrl and more effective than Anipryl
Lysodren (Op, DDD)
as the animal ages, MAOB (monoamine oxidase-type B) production is increased and this results in a decrease of dopamine, which in turn results in hyperadrenocortism. this is given to the patient inhibinting the production of MAOB. Dopamine metabolism is restored and clin signs of cushings are minimized
Anipryl (L- Deprenyl & Selegiline HCL)
this is an enzyme blocker of steroids synthesis acting specifically on the zona fasiculata to prevent the production of glucocorticoids or to prevent there release. Although this drug is the "latest and greatest" it is expensive , short lived in the system (not even 8 hrs) and is not as safe as op DDD
Anipryl is also used for ____ in humans
_________ is a condition known as Addisons disease. It occurs when the adrenal cortices cannot produce adequate levels of ______ resulting in the increase in the retention of ______.
Hypoadrenocorticism; Aldosterone; potassium
_____ and ______ are also produced in the zona reticularis in small quantities by the adrenal cortex in bothe male and female animals. Some are converted into _____ though biochemical means
Androgens and testosterone; estrogen
The adrenal medulla is stimulated by neurons from the ___________ to produce epinephrine and norepinephrine.
sympathetic nervous system
only 1% of pancreatic cells are endocrine in function and these are called _______
islets of langerhans
secrete a hormone called glucagon. This causes an increase in the blood glucose levels by stimulating the breakdown of glycogen in muscle and the liver.
secrete the well known insulin in response to a rise in blood glucose, for example, following a meal, Insulin promotes the uptake of glucose by cells and the conversion of glucose into glycogen by the liver and muscle tissue.
produce a hormone called somatostatin, which is secreted in response to peaks of insulin or glucagon production suppressing their release, thereby avoiding dramatic swings in the levels of blood glucose.
produce a hormone called pancreatic peptide. It is thought to affect the production of some of the pancreatic digestive enzymes and inhibit the contraction of the glall bladder.
is associated with the inability of an animal to produce adequate amounts of Antidiuretic Hormone (vasopressin), animals with this cannot control the amount of water secreted in the urine, and produce copious qunatities of dilute urine
the hormone called ____ produced by the testis and ovary, has a negative feedback upon the production of FSH from the anterior pituitary in both the male and female
Ovaries in the female produce two hormones depending upon what stage of ovulation
Estrogens are produced by the developing cells of the follicle, prior to ovulation
progesterone is produced by the corpus luteum of the ovary following ovulation
A third hormone is produced by the female during pregnancy in the corpus luteum placenta and uterus