Module 1 Flashcards
_____________ communicated physically, using electrochemical
signals between the brain and other organs, such as muscle group, or signals
from one organ to another, as in a ___________
Nervous System
Reflex arc
____________ communicated via chemical blood-borne messengers, for instance between the ____________and the ______________.
Endocrine System
Pituitary Gland and Adrenal Cortex
its communication via ___________ is very rapid
nervous system
its communication via ____________ is slower
endocrine system
It is customary and convenient to categorize _____________, _____________, ______________,
_______________, _____________, and _____________ functions
into physiological systems, anatomic and functional components of thesesystems overlap to lesser or greater degrees.
Cardiovascular
Respiratory
Reproductive
Gastrointestinal
Nervous
Endocrine
it is significantly dependent on hormones from the endocrine system for normal function
nervous system
considered a component of
the endocrine system, ishighly integrated
with the nervous system
adrenal medulla
What is Endocrinology?
it is the study of communication
within a living organism by means of hormones.
What is hormone?
are the chemical messengers of the
endocrine system
The discipline of endocrinology includes the?
✓ study of hormones
✓ the anatomy and physiology of the cells,tissues, and organs that produce these
hormones
✓ the way that hormones are transported
and action target cells
✓ clinical abnormalities of hormonal deficiencies and overproduction.
In the classical sense, a hormone was described as a?
chemical messenger secreted from a ductless gland, emptied directly into the circulation, and transported by the blood
Components of the endocrine system that
communicate by routes other than blood vessels
are characterized as;
✓ Paracrine
✓ Autocrine
✓ Neurocrine
✓ Solinocrine
hormones
are secreted locally into the extracellular
space only to self-regulate thevery cells that
released them
Autocrine communication
involves secretion of hormones from a cell directly into the
surrounding extracellular space; the hormone then interacts with adjacent or nea-rby cells without being transported by blood
Paracrine communication
delivers very high concentrations of the hormone
to its target site.
Paracrine communication
involving
secretion of peptides or other neurotransmitter molecules by neurons,is a specialized form of paracrine function in which
the chemical messenger is transferred to a
target cell via asynapse or neuromuscular
junction
Neurocrine communication
Several hormones are secreted directly into the lumen of the gastrointestinal, respiratory and
reproductive tracts. This type of communication is called?
Solinocrine
example of solinocrine
gastrin, somatostatin, vasoactiveintestinal peptide, calcitonin, secretin, and serotonin
Functions of Hormones
✓ A single hormone can affect a single function
✓ single hormones having
multiple actions
✓ multiple hormones having single actions
✓ multiple hormones producing multiple
actions
Example of A single hormone can affect a single function
✓ erythropoietin on hemoglobin synthesis by erythrocytes, but this one-on-one action is very rare.
example of multiple hormones having single actions
✓ regulation
of lactation by prolactin, placental lactogens ,corticosteroids, thyroxine, sex steroids, and oxytocin
Example of multiple hormones producing multiple
actions
reproductive steroids, oxytocin,
and corticosteroids on pregnancy, fetal development, and parturition.
it depends on the effects of
hormones on gametogenesis as well as development of sexual characteristics and elicitation of behaviors that culminate in the fertilization of
an oocyte by a spermatozoon and the production
of offspring
Reproduction
Many hormones play important functions
for the maintenance of pregnancy, such as?
✓ embryo and fetus
✓ development of the reproductive tract for pregnancy
✓ and initiation of parturition
are also important in timing the cessation of growth
hormones
Example of why hormone are important in timing the cessation of growth?
hormone-mediated closure of the epiphyses of
long bones after maturity is necessary for proper
adult body conformation
Maintenance of an animal’s internal environment requires metabolic energy generated
from nutrients processed by enzymes regulated by hormones. Such as.
✓ Production
✓ storage
✓ utilization of energy-require complex endocrine-regulated
ingestive, digestive, anabolic, catabolic, and excretory processes.
protein hormones include?
Prolactin and growth hormone
Glycoprotein hormones include?
✓ thyrotropin or thyroid stimulating hormone (TSH)
✓ luteinizing hormone (LH)
✓ follicle-stimulating hormone
(FSH)
Peptide hormones include?
✓ insulin
✓ insulin-like growth factor-1 (IGF-1)
✓ adrenocorticotropic hormone (ACTH)
hormones that are derivatives of amino acids?
✓ Triiodothyronine (T3)
✓ catecholamines such as epinephrine and norepinephrine
The large category of lipidic hormones includes
the subcategories of steroids;
✓ progesterone
✓ estrogens
✓ androgens
✓ glucocorticoids
✓ mineralocorticoids
Example of eicosanoids
✓ prostaglandin
✓ thromboxanes
✓ leukotrienes
chemical nature of hormone
present in the blood and other extracellular fluids in low concentrations
The range of hormone concentration from in extracellular fluids;
10^-11 to 10^-9 M
The range of concentrations of
nonhormonal amino acids, peptides,
and lipids:
10^-5 to 10^-3 M
synthesized by
Leydig cells of the testis, diffusesonly a short
distance to Sertoli cells and to the adluminal
compartment ofthe seminiferous epithelium
to promote spermatogenesis
testosterone
the hormonally active
form of testosterone in the male, is produced
by androgen-sensitive target cells such as
those of the prostate
Dihydrotestosterone
is converted to T3
within cells of the pituitary glandto play a
major role in the regulation of TSH secretion
Thyroxine (T4)
one anatomic feature that efficiently dir-
ects hormones to their target tissues is the so-
called?
portal circulation
consists of blood flow from capillaries in one
organ to a vein and then to capillaries in another
organ.
Portal circulation
Adrenocorticotropin (ACTH) is a
39-amino acid peptide derived from a much
larger precursor (235 amino acids) called?
proopiomelanocortin (POMC)
Other peptides with hormonal
activity derived from POMC include :
(i)
melanocyte-stimulating hormone
(ii) beta-endorphin
(iii)beta-lipotropin.
is synthesized as part of a larger precursor by the
chief cells of the parathyroid gland.
parathyroid hormone
other prohormones
(i) proinsulin
(ii) proglucagon
(iii) progastrin
(iv) procalcitonin.
a prohormone, is
converted to the hormone triiodothyronine (T3) in the liver,kidney,
brain, and pituitary gland.
Thyroxine (T4)
produced from androgen precursors, primarily androstenedione in females
and testosterone in males, by enzymes present in peripheral nonendocrine tissues
Estrogens
synthesize the hormone at faster rates, efficiently process prohormones, and havemechanisms for releasing the hormone in a controlled manner
endocrine glands
Water-soluble hormones
Proteins and peptides
do not require additional carrier proteins for transport
water-soluble hormones
the ___________ hormones
such as ____________ and ___________ require carrier proteins
insoluble
iodothyronines and steroids
found within the sequence of a larger gastrointestinal form of glucagon
called enteroglucagon, glicentin, or glucagon-like immune reactivity.
Pancreatic glucagon
require carrier proteins.
insoluble proteins
Ex. iodothyronines and steroids
means regulation of hormonal secretion from an endocrine gland by an effect of the circulating hormone that the gland itself
produces.
feedback control
negatively controls PTH secretion, glucose negatively
controls glucagon and positively
controls insulin secretion, and the volume of extracellular fluid negatively controls aldosterone
production by feedback mechanism
ionized calcium
A few hormones are produced without feedback regulation. Those produced
by the placenta, such as;
equine chorionic
gonadotropin
progesterone
estrogens
All hormone receptors are proteins
and have two functional domains;
✓ recognition domain
✓ coupling domain
that regulates
post-binding biochemical events
coupling domain
General principles of hormone action
✓ Intracellular Action of Steroid Hormones
✓ Intracellular Action of Iodothyronines
✓ Intracellular Actions of Protein and Polyp-
eptide Hormones
Second messenger for hormonesthat
bind to cell surface receptor include
cyclic
AMP (cAMP)
Concentrations of cyclic AMP increaseor decrease in response to
many hormones, including;
ACTH, LH, FSH, calcitonin, and PTH
a process mediated by a family of stimulatory and inhibitory regulatory proteins.
adenylate cyclase
Changes in ionized calcium within the
cell regulate a protein
Calmodulin
The four criteria for assay validity are;
(i) specificity
(ii) accuracy
(iii) precision
(iv) sensitivity.
defined as freedom from
interference by substances other than the
one intended to be measured
specificity
the extent to which a set of
measurements of a substance agrees with
the exact amount ofthe substance that is
present
accuracy
the extent to which a given set
of measurements of the same sample agrees
with the mean
precision
defined as the smallest amount
of unlabeled hormone that can be distinguished from havingno hormone in the sample.
sensitivity
is often the result of an autoimmune process whereby
the thyroid gland isinvaded by immune
cells and the hormone-secreting cells are
destroyed
Primary Hypothyroidism
can be due to
insufficient secretion of TSH, but it should be distinguishedfrom “hypothyroxinemia”, which can be produced by
concurrent disease, e.g., hyperadren-
ocorticism,malnutrition, and certain
drugs.
Secondary Hypothyroidism
in dogs, can occur as a result of a developmental defect whereby hormone-secretingcells of the anterior
pituitary gland fail to differentiate completely, leading to multiple deficiencies
panhypopituitarism
owing to diminished FSH and LH secretion
hypogonadism
caused by reduced ACTH secretion
secondary hypoadrenocorticism
young puppies will express the
condition as _____________ because there is
a lack ofgrowth hormone secretion
pituitary dwarfism
caused by excessive production of cortisol by the
adrenal cortex
Hyperadrenocorticism
results from excessive secretion of
ACTH by the pituitary gland, causing morphologic and functional hyperplasia ofthe adrenal
cortex.
Secondary hyperadrenocorticism (Cushing’s
disease)
is due to
excessive autonomous secretion of parathyroid
hormone
Primary hyperparathyroidism
is one of the most common
endocrinopathies in cats and is related to the excessive secretion of iodothyronines by proliferative lesions of the follicular cells of the thyroid gland
hyperthyroidism
caused by neoplasia of the pancreatic beta cells, leading to hypoglycemia.
Hyperinsulinemia
is an unfavorable responseto therapy caused by the therapeutic effort itself
iatrogenic disease
The disease shows the same manifestation as _____________, which is the spontaneous disease
Cushing’s syndrome
which can be produced by
concurrent disease, e.g., hyperadrenocorticism,malnutrition, and certain
drugs.
hypothyroxinemia
