Endocrine System Flashcards
Difference between endocrine and exocrine giving two examples each
An exocrine gland is a gland that secretes its products into ducts that lead to the target tissue. Examples of exocrine glands are sweat, salivary, sebaceous, mucous gland. An endocrine gland is a gland which secretes its products directly into the blood stream. Examples of endocrine glands are pituitary gland, ovaries, testes, thyroid gland, adrenal glan
Define paracrine signal
Signals that act locally between cells that are close together are called paracrine signals.
Signaling cell targets a nearby cell
Paracrine secretion :Substance released by cell that affects neighboring cells.
Example- Histamine released at site of injury to constrict blood vessel walls and stop bleeding
Define autocrine signaling and autocrine secretion
Cell targets itself
Autocrine signals are produced by signaling cells that can also bind to the ligand that is released. This means the signaling cell and the target cell can be the same or a similar cell (the prefix auto- means self, a reminder that the signaling cell sends a signal to itself
Neighboring cells of the same type or the secreting cell itself
●Substance released by cell that affects the secreting cells itself.
Example: Norepinephrine is released by a secretory cell in the adrenal medulla, and norepinephrine itself inhibits further release by the cell
Define endocrine signaling
Signal cell targets a distant cell through the bloodstream
called hormones, signaling molecules that are produced in one part of the body but affect other body regions some distance away.
Hormones travel the large distances between endocrine cells and their target cells via the bloodstream,
Example bloodstream that affects distant cells.
●e.g. Estrogen is secreted by ovary
Define neurocrine signaling
Signaling cell targets a cell
connected by gap junctions
Gap junctions in animals and plasmodesmata in plants are connections between the plasma membranes of neighboring cells. These water-filled channels allow small signaling molecules, called intracellular
The transfer of signaling molecules communicates the current state of the cell that is directly next to the target cell
Example of neurocrine secretion : Oxytocin, vasopressin and the releasing hormones of the hypothalamus.
Which two ways are hormones regulated by homeostasis
Nerves ●fast ●governing ●Hormones ●mainly metabolism, growth, differentiation, reproduction Homeostasis
What is endocrinology
The study of chemical communication systems that provide the means to control a huge number of physiologic processes
Name five differences between nervous system and endocrine system
Nervous system: Local actions ●point-to-point ●muscles & glands ●Nerve fibers ●rapid ●Short duration ●Action potentials
Endocrine System ●Distant actions ●target cells ●activities of cells ●Body fluid ●slow ●Longer duration ●Hormone
Name two importance of endocrine system
Endocrine glands release hormones into the bloodstream. This lets the hormones travel to cells in other parts of the body.
The endocrine hormones help control mood, growth and development, the way our organs work, metabolism , and reproduction.
The endocrine system regulates how much of each hormone is released. This can depend on levels of hormones already in the blood, or on levels of other substances in the blood, like calcium.
Name the primary endocrine glands
hypothalamus pituitary thyroid parathyroids adrenals pineal body the ovaries the testes
Importance of the hypothalamus
system. Nerve cells in the hypothalamus make chemicals that control the release of hormones secreted from the pituitary gland.
Name five hormones secreted by the pituitary gland
growth hormone, which stimulates the growth of bone and other body tissues and plays a role in the body’s handling of nutrients and minerals
prolactin (pronounced: pro-LAK-tin), which activates milk production in women who are breastfeeding
thyrotropin (pronounced: thy-ruh-TRO-pin), which stimulates the thyroid gland to make thyroid hormones
corticotropin (pronounced: kor-tih-ko-TRO-pin), which stimulates the adrenal gland to make certain hormones
antidiuretic (pronounced: an-ty-dy-uh-REH-tik) hormone, which helps control body water balance through its effect on the kidneys
oxytocin (pronounced: ahk-see-TOE-sin), which triggers the contractions of the uterus that happen during labor
The pituitary also secretes endorphins (pronounced: en-DOR-fins), chemicals that act on the nervous system and reduce feelings of pain. The pituitary also secretes hormones that signal the reproductive organs to make sex hormones. The pituitary gland also controls ovulation and the menstrual cycle in wome
Name a hormone produced by the thyroid gland
makes the thyroid hormones thyroxine (pronounced: thy-RAHK-sin) and triiodothyronine (pronounced: try-eye-oh-doe-THY-ruh-neen). These hormones control the rate at which cells burn fuels from food to make energy. The more thyroid hormone there is in the bloodstream, the faster chemical reactions happen in the body.
Importance of the parathyroid hormone
work together called the parathyroids (pronounced: par-uh-THY-roydz). They release parathyroid hormone, which controls the level of calcium in the blood with the help of calcitonin (pronounced: kal-suh-TOE-nin), which the thyroid makes.
Hormones produced by the adrenal gland
The outer part is the adrenal cortex. It makes hormones called corticosteroids (pronounced: kor-tih-ko-STER-oydz) that help control salt and water balance in the body, the body’s response to stress, metabolism, the immune system, and sexual development and function.
The inner part is the adrenal medulla (pronounced: muh-DUH-luh). It makes catecholamines (pronounced: kah-tuh-KO-luh-meenz), such as epinephrine (pronounced: eh-puh-NEH-frun). Also called adrenaline, epinephrine increases blood pressure and heart rate when the body is under stress.
Name three hormones produced by the pancreas
The pancreas (pronounced: PAN-kree-us) makes insulin (pronounced: IN-suh-lin) and glucagon (pronounced: GLOO-kuh-gawn), which are hormones that control the level of glucose, or sugar, in the blood. Insulin helps keep the bod
Name three enzymes produced by the adrenal gland
Cortisol. ... Aldosterone. ... DHEA and Androgenic Steroids. ... Epinephrine (Adrenaline) and Norepinephrine (Noradrenaline) ... Adrenal Insuffici
Name three hormones produced by the heart
peptides: atrial natriuretic peptide (ANP), brain (or B-type) natriuretic peptide (BNP), and C-type natriuretic peptide (CNP)
What are the major endocrine glands
Pineal glands
Pituitary gland
Thyroid gland
Hypothalamus
Who was the first person to use the term hormone
Ernest Henry Starling
What is hormone
A chemical messenger synthesized by specific endocrine cells in response to certain stimuli and secreted into the blood which carries it to the target cells
What is the function of hormones
Regulation of metabolism, growth and development, water and electrolyte balance, reproduction, and behavior
Name the principles of the hormonal control system
Modes of Delivery ●Classification ●Transport and Clearance ●Control of hormone secretion ●Candidate hormones ●Mechanism of action
Why is a cell a target
cell is a target because it has a specific receptor for the hormone
Name three characteristics of hormones
Specificity
●Highly active
●Interaction between hormones
Define synergistic,antagonistic and permissive action
Synergistic action: two hormones act together in a greater or more extensive than the sum of each ne Interactions | Boundless Anatomy and Physiology
Synergy. Synergism occurs when two or more hormones combine to produce effects greater than the sum of their individual effects.
●e.g. GH→ glucose↑ Glucagon →glucose↑
●Antagonistic action: hormones that have opposite effects
●e.g. Insulin →glucose↓ Glucagon →glucose↑
●Permissive action: require previous or simultaneous exposure to two or more hormones. Permissiveness is the situation in which a hormone cannot exert its full effects without the presence of another hormone.
Name three hormonal classification
Amine hormones ●Thyroid hormones, E, NE ●Polypeptide and protein hormones ●Pituitary hormones, insulin and glucagons ●Steroid hormones ●Sex hormones, cortisol and aldosterone
The posterior pituitary gland secreted which hormones
The Posterior Lobe of the Pituitary Gland (or neurophpophysis) stores and releases hormones secreted by the hypothalamus section of the brain including:
ADH (Antidiuretic hormone) stimulates the smooth muscles, blood vessels and the intestine. ADH increases the kidney’s permeability to water allowing the body to re-absorb water that would otherwise escape in urine.
OT (Oxytocin) stimulates the smooth muscles of the uterus during pregnancy, causing it to contract during labour. It also stimulates the lacteals (milk ducts) in the breast.
Define negative feedback
Characteristic of control systems in which system’s response opposes the original change in the system.
●Hormone itself feeds back to inhibit its own synthesis.
●Regulated product (metabolite) feeds back to inhibit hormone synthesis by the gland tha is synthesizing it
●Important for homeostatic control.
●Example: TSH and Thyroid hormone
Positive feedback
Characteristic of control systems in which system’s response increases the original change in the system
●Amplifies the deviation from the normal levels.
●Important for amplification of level for action.
●Example:
●Luteinizing hormone (LH) and Estradiol
●Estradiol induces the preovulatory surge of LH, which induces ovulation.
●Prolactin ( suckling )-suckling induces secretion of prolactin from anterior pituitary gland
How is hormone secretion regulated
Negative feedback
Positive feedback
Other hormones
Neurons or nerve regulation: pain, emotions, sex, injury, stress,…
●e.g. oxytocin with nipple stimulation or production of NE or E from the adrenal medulla
Cyclical Variations
Classes of hormones
Amine examples- thyroid hormones, E and NE
Steroid- sex hormones, cortisol and aldosterone
Polypeptide and protein hormones -insulin,glucagon,pituitary hormones
How are proteins and polypeptides synthesized
Preprohormones are synthesized on the ribosomes. These preprohormones are inactive forms so they are converted to pro hormones by the rough endoplasmic reticulum or they are cleaved to prohormones by proteolytic enzymes in the rough endoplasmic reticulum
A preprohormone is the precursor protein to one or more prohormones, which are in turn precursors to peptide hormones. In general, the protein …
And In the Golgi apparatus, prohormones are packaged into secretory vesicles. There they are converted to hormones which is the active form of preprohormones and peptides.
The vesicles store these hormones. The hormones are released from the vesicles thru exocytosis
What is modified by enzymes to make steroid hormones
Cholesterol
How are hormones transported in the blood
Transport of Hormones in the blood
●Water-soluble Hormones Are (e.g.catecholamine, polypeptides)
Dissolved in the plasma
Steroid and Thyroid Hormones are
Free (active) or are bound by proteins Protein-binding (inactive)
How are hormones cleared
Metabolic destruction by the tissues
●Major organs: Liver and Kidney
●Binding with the tissues
What kind of hormones are easily cleared
Free hormone ( they are carried in the blood as free chemicals)because their half life is in minutes while hormones that are bound to plasma protein carrier molecules last longer cuz their half life is in mins ,days,hours
What determines the level of hormones in the blood
Rate of release
(2) Rate of inactivation or removal
The adrenal cortex is stimulated by which hormone
Adrenocorticotropic hormone
How do other hormones control hormone secretion
eurons
●Other Hormones
●The secretion of a particular hormone is directly controlled by the blood concentration of another hormone. ( e.g., TSH → T3,T4↑)
●The tropic hormone usually stimulate not only secretion but also the growth of the stimulated gland. (e.g., TSH → the size of Thyroid gland↑)
Growth hormone is higher at wha time of the day
In the night
How do hormones act
They bind to receptors
This triggers signal transduction in the cell leading to activation of cellular responses
Name the receptor types and the way receptors are regulated
Membrane receptor
●Intracellular receptor
Up-regulation: ↑ in the number of receptors for a hormone in the target cell.
●Down-regulation: decrease in number of receptors for a hormone in the target cell
Permissiveness: Permissiveness : the facilitation of the action of one hormone by another
Permissiveness : hormone A must be present
for the full strength of hormone B’s effect.
Example: he ability of thyroid hormone to “permit” epinephrine-induced release of fatty acids from adipose tissue cells
1.Epinephrine causes a large release of fatty acids in the presence of thyroid hormone.
2.Thyroid hormone stimulates
the synthesis of beta-adrenergic receptors for epinephrine in adipose tissue
3.The tissue becomes much more sensitive to epinephrine.
How do peptide hormones act
Peptides and proteins hormone cannot freely penetrate plasma membrane
●Bind to membrane receptors
●Activate the intracellular second messenger using signal transduction
●cAMP, Ca 2+ . etc
How do steroid hormones act
The steroid hormones penetrate the cell membrane of the target cell and bind to intracellular receptors. The steroid receptor complex binds to DNA turning specific genes on or off
Name three differences between the hormone action of peptide hormones or catecholamines and steroid hormones
Peptides- faster,use secondary messengers, uses receptors to cell membrane
Steroid- slower, uses gene expression, uses receptors to cytoplasm to nucleus
How is hormone secretion measured
Concentrations of Hormons in the circulating blood
●Pg/ml ~ g/ml
●Hormonal secretion rate
●g/day ~ mg/day
