Chapter 17 PowerPoint Flashcards
Homeostasis?
Steady state of body systems that living organisms maintain
Autocrine
A chemical signal that elicits a response in the same cell that secreted it
Paracrine?
A chemical signal that elicits a response in neighboring cells; also called paracrine factor
Endocrine?
Relating to or denoting glands which secrete hormones or other products directly into the blood
What are the four classes of hormones?
Amino acid derivatives (amine hormones)
Peptide hormones
Protein hormones
Steroid hormones
What do hormones do?
Where?
What do the bind to?
Hormones circulate freely or travel bound to special carrier proteins
What are amino acid derivatives (amine hormones)?
Derivatives of tyrosine:
-____ hormones
-____
epinephrine, norepinephrine, dopamine
Derivatives of ____:
-serotonin, melatonin
Small molecules structurally related to amino acids
Derivatives of tyrosine:
-thyroid hormones
-catecholamines
epinephrine, norepinephrine, dopamine
Derivatives of tryptophan:
-serotonin, melatonin
What are the three catecholamines?
Epinephrine, norepinephrine, dopamine
What are two derivatives of tryptophan?
Serotonin and melatonin
What are peptide hormones?
What are they synthesized as?
chains of amino acids
most are synthesized as prohormones
(Inactive molecules converted to active hormones before or after they are secreted)
What are short chain polypeptides?
-2 examples
antidiuretic hormone (ADH) and oxytocin (OXT) (each 9 amino acids long)
[2-50 linked amino acids]
What are protein hormones?
-2 examples
small proteins
growth hormone (GH; 191 amino acids) and prolactin (PRL; 198 amino acids)
What are steroid hormones derivatives of?
Cholesterol
What are steroid hormones released by?
The reproductive organs (androgens by the testes in males, estrogens and progestins by the ovaries in females)
The cortex of the adrenal glands (corticosteroids)
The kidneys (calcitriol)
What type of hormone remains in circulation the longest and why?
Because circulating steroid hormones are bound to specific transport proteins in the plasma: they remain in circulation longer than secreted peptide hormones
How long do free hormones remain functional?
Less than 1 hour
What are three ways free hormones are gotten rid of?
Diffuse out of bloodstream and bind to receptors on target cells
Are broken down and absorbed by cells of liver or kidneys
Are broken down by enzymes in plasma or interstitial fluids
Thyroid and Steroid Hormones
remain in circulation much longer because most are “bound”
enter bloodstream
>____% become attached to special transport proteins
bloodstream contains substantial reserve of ____ ____?
Thyroid and Steroid Hormones
remain in circulation much longer because most are “bound”
enter bloodstream
>99% become attached to special transport proteins
bloodstream contains substantial reserve of bound hormones
What is a hormone receptor?
Responds to several ____ hormones?
Different tissues have different ____ of receptors?
Presence or absence of specific receptor determines hormonal ____?
A protein molecule to which a particular molecule binds strongly
Responds to several different hormones
Different tissues have different combinations of receptors
Presence or absence of specific receptor determines hormonal sensitivity
First messenger?
A hormone that binds to a cell membrane hormone receptor and triggers activation of a second messenger system
Second messenger?
A molecule that initiates a signaling cascade in response to hormone binding on a cell membrane receptor and activation of a G protein
What are three important 2nd messengers?
Cyclic-AMP (cAMP)
-Derivative of ATP
Cyclic-GMP (cGMP)
-Derivative of GTP
Calcium ions
G protein?
A protein associated with a cell membrane hormone receptor that initiates the next step in a second messenger system upon activation by hormone–receptor binding
Enzyme complex coupled to membrane receptor
Involved in link between 1st messenger and 2nd messenger
Adenylyl cyclase?
A membrane-bound enzyme that converts ATP to cyclic AMP, creating cAMP, as a result of G-protein activation
____ ____ is activated when hormone binds to membrane receptor and changes concentration of cAMP within cell?
↑ ____ level accelerates metabolic activity within cell
Adenylate cyclase
cAMP
How do hormones and plasma membrane receptors work? (Water soluble)
Chapter 17 page 739 or slides 15-140
How do hormones and intracellular receptors work? (Lipid soluble)
Chapter 17 page 739 or slide 19
Hormones and Intracellular Receptors:
Alter rate of DNA transcription in ____?
(-Change patterns of protein synthesis)
Directly affect metabolic activity and structure of ____ cell?
Include ____ and ____ hormones
Nucleus
Target
Steriods and thyroid
Neuroendocrine reflexes?
Pathways include both neural and endocrine components
(A physical stimulus causes a nervous signal, which triggers the release of hormones from the brain into the blood)
Complex Commands involve ____ hormones?
Issued by changing:
-____of hormone secreted?
-____ of hormone release?
Hypothalamic and pituitary hormones
released in sudden bursts
Frequency changes response of target cells
Complex Commands involve many hormones?
Issued by changing:
-Amount of hormone secreted?
-Pattern of hormone release?
Hypothalamic and pituitary hormones
released in sudden bursts
Frequency changes response of target cells
Down-regulation?
-Presence of a hormone triggers decrease in number of hormone receptors
-When levels of particular hormone are high, cells become less sensitive to it
A decrease in the number of hormone receptors, typically in response to chronically excessive levels of
a hormone
Up-regulation?
-Absence of a hormone triggers increase in number of hormone receptors
-When levels of particular hormone are low, cells become more sensitive to it
An increase in the number of hormone receptors, typically in response to chronically reduced levels of a
hormone
Cells ____ through downregulation of steroid receptor?
Desensitize
Pituitary gland?
Bean-sized organ suspended from the hypothalamus that produces, stores, and secretes hormones in
response to hypothalamic stimulation (also called hypophysis)
The Pituitary Gland
-also called ____?
-lies within ____ ____?
____ ____
a dural sheet that locks pituitary in position
isolates it from cranial cavity
-hangs inferior to ____?
-connected by ____?
The Pituitary Gland
-also called hypophysis
-lies within sella turcica
Sellar diaphragm
a dural sheet that locks pituitary in position
isolates it from cranial cavity
-hangs inferior to hypothalamus
-connected by infundibulum
Infundibulum?
Stalk containing vasculature and neural tissue that connects the pituitary gland to the hypothalamus (also
called the pituitary stalk)
The Pituitary Gland:
Releases ____ important peptide hormones?
Hormones bind to ____ ____
use ____ as second messenger?
The Pituitary Gland:
Releases 9 important peptide hormones
Hormones bind to membrane receptors
use cAMP as second messenger
Hypophyseal portal system?
A network of blood vessels that enables hypothalamic hormones to travel into the anterior lobe of the pituitary without entering the systemic circulation
Blood vessels link two capillary networks
Entire complex is portal system
-ensures that regulatory factors reach
intended target cells before entering general
circulation
Hypothalamic Control of the Anterior Lobe:
2 classes of hypothalamic regulatory hormones
____ ____(____)?
Stimulate synthesis and secretion of one or
more hormones at anterior lobe
____ ____(____)?
Prevent synthesis and secretion of hormones
from the anterior lobe
Rate of secretion is controlled by ____ ____?
Hypothalamic Control of the Anterior Lobe:
2 classes of hypothalamic regulatory hormones
Releasing hormones (RH)
Stimulate synthesis and secretion of one or
more hormones at anterior lobe
Inhibiting hormones (IH)
Prevent synthesis and secretion of hormones
from the anterior lobe
Rate of secretion is controlled by negative feedback
9 Hormones of the pituitary gland?
Chapter 17 pages 744&475 or slides 30-31
Parathyroid gland:
Number?
Location?
Size?
4 Parathyroid Glands
embedded in the posterior surface of the thyroid gland
altogether, the four glands weigh 1.6g
What hormone does the parathyroid gland secrete?
Parathyroid Hormone (PTH) or parathormone
PTH?
Parathyroid hormone is a peptide hormone produced and secreted by the parathyroid glands in response to low blood calcium levels
Parathyroid Hormone (PTH) or parathormone is
produced by parathyroid ____ ____ in response to low concentrations of ____ and is an antagonist for ____?
Parathyroid Hormone (PTH) or parathormone is
produced by parathyroid (chief) cells in response to low concentrations of Ca2+ and is an antagonist for calcitonin
Chief cells?
Produce and secrete PTH
What are the three effects of PTH?
It stimulates osteoclasts and inhibits osteoblasts
-accelerates mineral turnover and releases Ca2+ from bone
-reduces rate of calcium deposition in bone
It enhances reabsorption of Ca2+ at kidneys, reducing urinary losses
It stimulates formation and secretion of calcitriol by the kidneys
-effects complement or enhance PTH
-also enhances Ca2+, PO43- absorption by digestive tract