Endocrine System Flashcards
Chemical signals released into the blood and transported throughout the body
Need target cells in order to initiate a physical response
Hormones
2 criteria on how the signals are transmitted between animal cells
Type of secreting cell
Route taken by the signal in reaching the target
Hormones are secreted into the ECF by endocrine cells and reach their targets via the blood stream
Maintains homeostasis, mediates responses to stimuli, regulates growth and development
Endocrine Signaling
Molecule acts over short distances
Reach target cell by diffusion
Local regulator
Target cells lie near the signaling
Paracrine signaling
Target cell itself is the secreting cell
Autocrine signaling
Plays important role in blood pressure regulation, nervous system function, and reproduction
Local regulator
Function in blood clotting, immune system, and reproduction
Prostaglandin
Neurons form specialized junctions with the target cells
Synapses
signaling where Neurons form specialized junctions with the target cells
Synaptic signaling
Secreted by the neurons at the synapses
Diffuse short distances and bind to receptors on target cells
Neurotransmitters
Specialized neurosecretory cells secrete neurohormones that travel to the target cells
via the bloodstream
Neuroendocrine Signaling
signaling with Chemicals released by animals in their environment
Signaling by Pheromones
Chemicals released by animals in their environment
Serve as :
Mark trails leading to food
Defining territories
Warning of predators
Attracting potential mates
Pheromones
Modified fatty acids
Others are polypeptides, some are gases
Local Regulators
Gas that functions as both local regulator and neurotransmitter
Nitric oxide (NO)
Decrease oxygen in blood → ________ activates an enzyme that results in vasodilation → increase blood flow to tissue
Nitric oxide (NO)
3 classes of hormones
polypeptides, amines, steroids
water soluble homrones
olypeptides and amines
fat soluble homrones
steroids
- Secreted by exocytosis
- Travel freely in the bloodstream
- Bind to cell-surface receptors
-Bind to receptors in nucleus or cytoplasm of target cells
Water-soluble hormones
example of water soluble hormones
- Has multiple effects in mediating body’s response to short-term stress
- Binds to receptors on plasma membrane of liver cells
- Triggers the release of messenger molecules that activate enzymes and result in the release of glucose into the bloodstream
Epinephrine
(Water-Soluble hormones Pathway) Binding of hormones to its receptor initiates a ________________ leading to responses in the cytoskeleton, enzyme activation, or a change in gene expression
signal transduction pathway
- Diffuse across cell membranes
- Travel in bloodstream bound to transport proteins
- Diffuse through the membrane of target cells
- Bind to receptors in nucleus or cytoplasm of target cells
Lipid-soluble hormones
Response is usually a change in gene expression
Lipid-Soluble Hormones Pathway
Binds to its cytosolic receptor → hormone-receptor complex is formed and moves into the nucleus → receptor part will act as a transcriptional regulator of specific target genes
Steroid hormone
Same hormone may have different effects on target cells that have
- Different receptor for the hormone
- Different signal transduction pathway
multiple effects of _____
- Can increase blood flow to major skeletal muscles
- Can decrease blood flow to the GI tract
Epinephrine
Endocrine Tissues and Organs
Endocrine glands
Exocrine glands
Endocrine glands
Thyroid
Parathyroid
Testes
Ovaries
Exocrine glands
Salivary gland
Release of acidic contents from the stomach to the
duodenum
Stimulates endocrine cells to secrete secretin
Causes target cells in the pancreas to increase pH level in duodenum
Secretin
Simple Hormone Pathway
Released from an endocrine cell
Travel through the bloodstream
Interact with specific receptors within a target cell to cause a physiological response
Stimulus is received by a sensory neuron, which
stimulates a neurosecretory cell
Simple Neuroendocrine Pathway
secretes neurohormone, which enters the
bloodstream and travels to target cells
Neurosecretory cell
example of Neuroendocrine Pathway
Suckling of an infant
- Stimulates signals in the nervous system that reach the hypothalamus
- Nerve impulses in hypothalamus triggers the release of oxytocin in the posterior pituitary gland
- Release of oxytocin
Suckling of an infant
causes the secretion of milk from the mammary glands
oxytocin
Feedback Regulation
Negative feedback
Positive feedback
- Inhibits a response by reducing the initial stimulus
- Prevents excessive pathway activity
Negative feedback
Reinforces a stimulus to produce an even greater
response
Positive feedback
Produced by neurosecretory cells in the larval brain in invertibrates
Controls the molting of the larva
Prothoracicotropic Hormone (PTTH)
Directs the release of ecdysteroid
Prothoracic gland
Triggers successive molt as well as metamorphosis
ecdysteroid
not triggered until the level of juvenile hormone (JH) drops
Metamorphosis
Receives information from the nervous system
Initiate responses through the endocrine system
Hypothalamus
Attached to the hypothalamus
Made up of anterior pituitary and posterior pituitary
stores the hormones
Pituitary gland
Neurosecretory cells of hypothalamus synthesize 2 hormones
Both hormones are fast acting
Produce response within seconds of their release
Posterior pituitary gland
2 hormones of Posterior pituitary gland
Antidiuretic Hormone (ADH)
Oxytocin
Regulates milk secretion by the mammary gland
Oxytocin
Regulates physiology and behavior
Antidiuretic Hormone (ADH)
vasopressin
Acts on collecting ducts of kidneys
Increase water absorption
Increases blood pressure by constricting smooth muscles of arterioles
Acts centrally to increase thirst
Antidiuretic Hormone (ADH)
Hormone production is controlled by releasing
and inhibiting hormones secreted by the
hypothalamus
Consists of anterior lobe and intermediate lobe (absent in humans)
Anterior pituitary gland
responsible for the milk let down in mamary glands
prolactin releasing hormone
Anterior pituitary gland hormones
fsh
lh
tsh
acth
prolactin
msh
gh
Stimulates production of thyroid gland hormone
Thyroid-stimulating hormone
Promotes egg/sperm production
Follicle-stimulating hormone
Induces ovulation and corpus luteum and sex steroid production
Luteinizing hormone
Increases production and secretion of steroid hormones from adrenal cortex
ACTH
somatotropin
-Controls cell mitosis, synthesis of mRNA, and metabolism
-Acts indirectly with the help of insulin-like growth factor(IGF)
Growth Hormone (GH)
Excess GH
Lack GH
= gigantism
= dwarfism
Intermediate lobe hormones
Melanocyte-stimulating hormone (MSH)
Melanocyte-stimulating hormone (MSH)
Promotes dispersion of pigment in cells in body fishes, amphibians, and non-avian reptiles
Birds and mammals Role is unclear
Anterior pituitary gland hormones in a hormone cascade pathway
Tropic hormone
Set of hormones coming from hypothalamus, anterior pituitary gland, and a target endocrine gland
Hormone cascade pathway
Contains concentrates of iodine Produces triiodothyronine (T3) and thyroxine (T4)
Secretes calcitonin
Contain thousands of tiny sphere-like follicles that produce and store hormones
Promote normal growth and development of
nervous system and stimulate metabolic rate
Thyroid Gland
T4
T3
charactertistics
T4-greater amounts is produced
T3-more physiologically active
Regulate blood calcium level
calcitonin
Occurs in 2 pairs in humans
Birds and mammals
Removal of glands will cause blood calcium level to drop
Continuous decrease may lead to excitability, muscle spasms, tetany, and death
parathyroid gland
Secretes melatonin Related to biological rhythms
The release is controlled by suprachiasmatic nucleus
(SCN) found in the hypothalamus
pinneal gland
essential to calcium homeostasis
Parathyroid hormone (PTH)
Increases activity of osteoclasts
Results in increase of blood calcium levels
Decreases rate of the kidneys’ calcium exertion Increases production of another hormone, 1,25- dihydrovitamin D
Parathyroid hormone (PTH)
Most of the hormones are made from cholesterol
adrenal glands
Outer region and Inner region of adrenal glands
Outer region= adrenal cortex
Inner region= adrenal medulla
Corticosteroids
Mineralocorticoids
Adrenal sex hormones
Adrenal cortex
Epinephrine
Nonepinephrine
Adrenal medulla
in adrenal cortex
Influence food metabolism, inflammation, and stress
Promote synthesis of glucose from amino acids and fats by undergoing gluconeogenesis
ACTH controls synthesis and secretion
Glucocorticoids
in adrenal cortex
Regulate salt balance of body fluids
Promotes tubular reabsorption
of sodium and secretion of potassium in kidneys Salt-regulating action is controlled by renin-angiotensin system and blood levels of potassium
Mineralocorticoids
in adrenal cortex
Produces androgens that act similarly to testosterone
Adrenal sex hormone
Secretes epinephrine
(adrenaline) or norepinephrine (noradrenaline)
Functions
- Moderate constriction of arterioles
- Mobilization of liver glycogen and fat stores
Oxygen consumption
- Blood coagulation
- Activity of GI tract
adrenal medulla
Both exocrine and endocrine gland
Pancreas
secrete glucagon
Alpha cells
Endocrine portion of the pancreas
Islets of Langerhans
secrete insulin and amylin
Beta cells
secrete somatostatin
Delta cells
secret pancreatic polypeptide
Gamma cells
