The Endocrine system: Organization and Acute/Chronic Response to Exercise Flashcards
What does the endocrine system consist of? Describe the role of endocrine glands
Endocrine system consists of HOST organ, minute quantities of Chemical messengers and Target or Receptor organ (messages are sent from host to target organ)
- Endocrine glands have NO DUCTS and SECRETE substances directly into extracellular spaces around the gland
- they require a bloodstream
What is common feature for exocrine glands and where can they be seen in the body?
Exocrine glands- HAVE DUCTs and can be seen in digestive tract, within walls of GI tract, stomach and intestines
What are the major endocrine organs?
Major endocrine organs:
- Pituitary
- Parathyroid
- Adrenal
- Pineal
- Thymus glands
Also discuss other organs in the body that contain endocrine tissue.
Other organs that contain areas of endocrine tissue are Pancreas, gonads (ovaries and testes), hypothalamus, and Adipose tissues
Describe the function of the neuroendocrine system
Neuroendocirne system- Regulate and integrate body functions using hormones
What are hormones?
Hormones- Highly specialized organic molecules produced by Endocrine organs that regulates the function of specific target cells.
Differentiate between the types of local signaling and long-distance signaling
Local signaling; signals that act locally between cells close together
1. Paracrine and Autocrine
-paracrine signaling: cell produces signal to induce changes in NEARBY cells (local regulator diffuses across interstitial fluid)
-Autocrine signaling: a cells secretes hormones that bind to autocrine receptor of the same cell (secreting cell)
2. Neurtotanmission (Nerve system) - signaling molecules called NEUROTRANSMITTER are released by axon terminal of a neuron (presynaptic) and bind to receptor on another neuron (post-synaptic)
-neurotransmitter molecules diffuse across synapse
Long Distance signaling-
1. Endocrine signaling- signals (hormones) are produced by specialized endocrine cells and released into BLOODSTREAM, which carries them to target cells in distant parts of body
- Neurosecretory- neural signals produced by neurosecretory cell, relesed in blood stream to send to target cells in distant parts of body
What are the main categories of hormones and describe the different roles of hormones
Hormones are chemical substances synthesized by SPECIFIC host glands
Categories of Hormones:
-Steroid-derived hormones
-Amine and Polypeptide hormones
Most hormones circulate in the BLOOD as messengers that affect tissues a distance from the specific gland and others that exert LOCAL effects in their region of synthesis.
What is half-life?
Half-life- the time required to REDUCE a blood hormone’s concentration by one half and gives us an indication of how long its effects Persists
Describe the three major type of molecules that hormones can be.
Hormones can be:
- Amines and amino acids
- Peptides, polypeptides, proteins and glycoproteins
- Steroids
Differentiate between water soluble and water insoluble hormones
Water soluble hormones- circulate FREELY in BLOOD (need a carrier get across membrane)
Water-insoluble hormones- requires a CARRIER to enter Blood (can easily move across membrane)
Explain how water-insoluble and water soluble hormones enter the cell membrane
Water Soluble Hormones binds to cell-membrane RECEPTOR and activates signaling molecules (G-protein, adenyl cyclase-effector, cyclic AMP) to diffuse across membrane
Water insoluble hormones- diffuses across the cell membrane (easily) and binds to an activates an INTRACELLULAR receptor- translocates to the nucleus
-Affects GENE TRANSCRIPTION.
What are the main hormones under Amine hormones ?
Amine Hormones: Catecholamines (epinephrine, norepinephrine) and Thyroid hormones (thyroxine, T4 and T3)
Describe which of the form main categories are similar and its common features
peptide and Catecholamines (amine) are Most similar as they both have SHORT half life, dissolved in plasma. and activate second messenger systems, modify existing proteins made in advance, secretory vesicles
STEROID hormones and THYROID hormones are very similar and have common features like LONG lifespan ( half life), induction of new protein synthesis, activate genes for transcription and translation, bound to carrier proteins for transport, released from parent cell through simple diffusion and made from précursors
which hormones are peptide hormones,?
Peptide hormones- Insulin, glucagon, Leptin, IGF-1
which hormones are steroid hormones?
Steroid hormones: Androgens, DHEA, Cortisol
Which hormones are Amine hormones (catecholamines, and Thyroxine (T4) )?
Amine hormones:
Catecholamines: Epinephrine/Norepinephrine
Thyroid Hormones:
Thyroxine (T4), and Triiodothyrodine (T3)
What organ produces atrial natriuretic hormone and what stimulates its production. what is this hormone’s function?
Atrium of the heart produces atrial natriuretic hormones. This hormones is produced by stimulus of Atrial stretching.
The hormone will target kidneys and inhabit Na+ reabsorption and renin release
it will also target Adrenal Cortex and inhibit secretion of aldosterone
Explain the ways in which hormones can alter cellular reactions of target cells
Hormones can alter cellular reactions of specific target cells by:
- Modifying the rate of intracellular protein synthesis by stimulating nuclear DNA
- Changing rate of Enzyme activity
- Altering Plasma membrane transport via second-messenger system.
- Inducing secretory activity
Why is hormone receptor binding important. What determines a hormone’s ability to activate target cell?
Hormone-receptor binding (hormone bind to receptor) is FIRST Step in INITIATING hormone action
- The extent of a target cell’s activation by a hormone depends on:
- Hormone concentration in the blood
- The number of target cell receptors for the hormone
- Sensitivity or strength of the union between the hormone and receptor
Describe the action of non-steroid hormones. Provide examples of non-steroid hormones.
Non-steroid hormones (like Epinephrine and glucagon) will have downstream pathway of hormone binding to specific receptor, activating adenylate cyclase, and the adenylate cyclase activates Cyclic AMP and Protein kinase= active protein kinase which will allow active target enzyme to induce cellular response.
Explain the hormone effects on enzymes. How can a hormone increase enzyme activity?
Major hormone actions include altering enzyme activity and enzyme-mediated membrane transport
A hormone can increase enzyme activity by:
-Stimulating enzyme production
-Combining with the enzyme to alter its shape and ability to act, which increases or decreases the enzyme’s catalytic effectiveness
-Activating Inactive enzyme forms, thus increasing the total amount of active enzyme
Explain the importance of adjusting hormone secretion. What factors determine plasma concentration of hormones?
Hormone secretion usually adjusts rapidly to meet the demands of changing bodily conditions
Factors that determine plasma concentration of particular hormone:
-Quantity of hormone synthesized in host gland
-Rate of either catabolism (breakdown) or secretion into blood
-quantity of transport proteins present
-Plasma volume changes
(if decrease plasma volume, increase plasma concentration)
explain how secretion determines plasma concentration of hormone. what else besides secretion determines plasma concentration of hormone?
Secreted amount of hormone describes the plasma concentration and represents SUM of HORMONE Synthesis and release by the host gland; in addition to its uptake by receptor tissues and removal by liver and kidneys.
CHANGES in PLASMA VOLUME also alter hormone concentrations, independent of host organ’s secretion rate.
What are three main types of stimulation factors for endocrine gland activity ?
Endocrine Gland Activity stimulation factors:
- HORMONAL stimulation: Hormones influence secretion of other hormones
- HUMORAL stimulation; Changing levels of ions, and nutrients in blood, bile, and other body fluids stimulate Hormone release
- NEURAL stimulation- neural activity affects hormone release
Explain major examples of the stimulation factors for endocrine gland activity.
Endocrine gland stimulation:
- Hormonal stimulation:
- ACTH from anterior pituitary is released into blood
- This stimulates adrenal cortex to secrete glucocorticoids
- Glucocorticoids influence several target organs
- glucocorticoids exert negative feedback on ACTH release
- ACTH from anterior pituitary is released into blood
- Humoral stimulation:
1. Capillary blood containing high concentration of glucose
2. This will cause INSULIN to be secreted by pancreas (enter blood)
3. Target cells will absorb more glucose from blood
4. have Capillary blood in which glucose levels have dropped
5. Low blood sugar levels inhibit insulin release - Neural Stimulation:
1. Preganglionic sympathetic nerve fiber stimulates Adrenal Medullary cells
2. Adrenal medullary cells secrete CATECHOLAMINES into blood
Describe the pattern of hormone release and why it is important . What is the most common pattern?
Patterns of hormone release:
-Most hormones respond to PERIPHERAL STIMULI on an as-needed basis
-Some hormones release at regular intervals during a 24-hour cycle in a diurnal pattern or cycle of secretion
-Some secretory cycles span several weeks while others follow daily cycles
Ex: sleep cycle or women’s monthly period
Patterns of release and or Amplitude and Frequency of discharge provide MORE information on HORMONE DYNAMICS than simply examining mean concentration at any single time.
Describe where anterior pituitary is located and how many hormones it secretes. Also discuss what organ controls anterior pituitary activity and the additional thing primary pituitary hormones have and what controls them.
Anterior pituitary is located beneath the Base of the brain and Secretes SIX specialized polypeptide hormones (FLATPIG)
-The HYPOTHALAMUS controls the Anterior pituitary activity
-Each of the primary pituitary hormones has its own hypothalamic RELEASING Hormone called Releasing Factor
-NEURAL Input to Hypothalamus from Anxiety, stress and physical activity controls output of these Releasing factors.
-
What are the hormones located in the anterior pituitary?
Hormones in Anterior pituitary: FSH- Follicle stimulating hormone LH- Lutenizing hormone ACTH- Adrenocorticotropic hormone TSH- Thyroid stimulating hormone Prolactin Growth Hormone
List the main hormones that are located in the anterior pituitary and the target cells they stimulate.
Anterior pituitary:
Lactogen (prolactin) -stimulates the breast
Gonadotropic hormones (FSH, LH) that stimulate the ovaries and testes (produce estrogen, progesterone, and testosterone)
-ACTH (corticotropin) stimulates the adrenal cortex (which produces cortisol, aldosterone)
-Thyrotropin stimulates the thyroid which produces thyroxine (T4) and Triiodothyroinine (T3)
-Growth hormone (somatotropin) stimulates many organs
-Endorphins - stimulate diverse organs and tissues
What is the role of hypophysis?
Hypophysis- Portal system (connection) between the hypothalamus and pituitary
-it controls several endocrine glands and many physiological functions
What is the role of hypothalamus?
Hypothalamus- control center for the endocrine system- where Neural input (emotion, pain, body temp) and immune and inflammatory responses (CYTOKINES) are communicated to the endocrine system.
How are most pituitary hormones regulated?
Most pituitary hormones are regulated by HYPOTHALAMIC Stimulating Hormones via Hypophyseal portal system.
What is the pituitary gland also called? List the five types of cells in anterior pituitary gland
Pituitary gland aka MASTER Gland
5 types of cell in Anterior Pituitary Gland:
1. Somatotrophs- human growth hormone (hGH) (somatropin)
2. Thyrotrophs- Thyroid-Stimulating hormone
3. Gonadotrophs- Follicle stimulating hormone (FSH) and Lutenizing Hormone (LH) (gonadotropins)
4.Lactotrophs- prolactin (PRL)
5. Corticotrophs -adrenocroticotropic hormone (ACTH) (corticotropin)
Explain the role of Growth hormone in the body. Also include the ways that Growth Hormone facilitates protein synthesis in adults. How does it relate to carbohydrates?
Growth hormone promotes CELL DIVISION and CELLULAR PROLIFERATION
-In adults, Growth Hormone facilitates protein synthesis by:
1. increasing amino acid transport through the plasma membrane
2. Stimulating RNA formation
3. Activating cellular ribosomes that increase protein synthesis
Growth hormone also SLOWS Carbohydrate Breakdown and INITIATES subsequent Mobilization an use of FATS as an Energy source
What is the most plentiful anterior pituitary hormone?
HUMAN GROWTH HORMONE (hGH)
What is the main function of human growth hormone (hGH)?
Function of human growth hormone (hGH)- promote SYNTHESIS and SECRETION of INSULIN-like Growth Factors (IGFs) (somatomedins) by liver, skeletal muscle, cartilage, and bone cells
Describe the major roles of Insulin Growth Factors (IGFs)
Insulin Growth Factors (IGFs):
- ACCELERATE protein synthesis (increase cellular uptake of amino acids, INHIBIT breakdown of amino acids, inhibit Amino acid use in ATP production
- ENHANCE lipolysis in Adipose tissue- Release fatty acids for use in ATP production
- DECREASES use of glucose for ATP production in most body cells- available glucose is able to be used by neurons in times of glucose scarcity
Differentiate between the induction and inhibition of growth hormone. Does growth hormone undergo Negative feedback?
Induction- Growth Hormone-releasing hormone; GHRH (increasing activity of GH)
Inhibition- Growth hormone- inhibiting hormone; GHIH (decreases activity of GH)
GHIH (aka somatostatin)
Describe how physical activity affects Growth hormone and tissues in the body.
Physical activity EXTENDS GH’s (growth hormone) action on target tissues
- Benefits muscle, bone, and connective tissue Growth and Remodeling
- Optimizes the FUEL mixture during physical activity
- The net metabolic effect preserves plasma glucose concentration for Central nervous system and muscle functions
Compare and contrast Growth hormone level changes in trained and sedentary individuals. Which individual has higher GH levels during recovery?
Trained and sedentary individuals show similar INCREASES in GH Concentration with Exercise to Exhaustion, But SEDENTARY person maintains HIGHER GH levels for several hours into recovery.
Since sedentary can have higher gains, they have better way of improvement during exercise (so you want to spare glucose and use fat for fuel)
Describe the feedback control that occur in hypothalamus with growth hormone releasing and inhibiting hormone and its effects on target cells.
Hypothalamus secretes GHRH, GHIH, or somatostatin
Feedback control: can inhibit GHRH release and stimulate GHIH release from hypothalamus; which can further inhibit GH synthesis and release by Anterior pituitary
What are the direction and indirect actions for growth hormone? Be sure to include the effects on target cells.
Growth Hormone
Direct actions (anti-insulin):
-stimulate Triacyclgylerol release in Adipose tissue
-Hinders glucose uptake to maintain blood sugar level
Indirect actions (promote anabolism)
-Liver and other organs will stimulate somatomedins (IGFs):
Nonskeletal effects: increases synthesis of protein and new cell growth
Skeletal effects- increases formation of cartilage and promotes skeletal growth.
Explain how IGFs and Growth hormone relates. what do liver cells secrete due to GH stimulation? Discuss how IGF’s interact with receptors.
IGFs MEDIATE many of Growth hormone’s effects
-In response to GH stimulation, liver cells synthesize IGF-I and IGF-II
IGFs travel in the blood Attached to one of the five types of Binding proteins for release as FREE hormones to interact with SPECIFIC receptors
List the major factors that stimulate IGF (insulin like growth factors) Transport
Factors that influence IGF transport:
- Binding proteins within muscle
- Nutritional status
- Plasma insulin levels
Explain the role of ACTH and describe which system it is part of.
ACTH (adrenocorticotropic hormone) functions as part of Hypothalamic-Pituitary -Adrenal axis to Regulate adrenal cortex output of hormones
-ACTH acts directly to ENHANCE fatty acid mobilization from adipose tissue, INCREASE Gluconeogenesis, and STIMULATE protein catabolism.
Which molecules mediate ACTH release? Also what kind of actions favor the release of these mediators, that will induce ACTH.
Corticotropin Releasing Hormone (CRH) and Arginine VASOPRESSIN (AVP) Mediate ACTH release
-HIGH-INTENSITY Physical activity Favors AVP (vasopressin) release, while PROLONGED physical activity favors CRH release which both induces ACTH.
Describe the major function of ACTH and what occurs during induction and inhibition (including the molecules involved)
ACTH (adrenocorticotropic hormone) ACTH
Function: Controls the Production and Secretion of Cortisol other glucocorticoids by the adrenal gland.
Induction: Corticotropin-releasing hormone (CRH): Stress related stimuli (low blood glucose or physical trauma); interleukin-1 (macrophages)( increases release of ACTH)
Inhibition: Glucocorticoids INHIBIT CRH and ACTH.
Explain the role of thyrotropin, and also what is another name for this molecule?
Thyrotropin, aka THYROID-STIMULATING HORMONE (TSH) controls hormone secretion by the thyroid gland.
-TSH maintains GROWTH and DEVELOPMENT of Thyroid gland and Increases Thyroid Cell metabolism.
Describe the major function of TSH and the molecules that induce and inhibit it.
TSH (thyroid-stimulating hormone)-
Function: stimulates Synthesis and Secretion of triiodothyronine (T3) & thyroxine (T4) form the thyroid gland
Induced: thyrotropin-releasing hormone (TRH)
Inhibition: HIGH levels of T3 and T4 INHIBIT TRH (NEGATIVE FEEDBACK)
What are the main hormones in the posterior pituitary and what are their functions. Also discuss how physical activity affects these hormones
Posterior pituitary hormones: ADH (vasopressin) and OXYTOCIN (stored hormones)
- ADH Influences Water Excretion by Kidneys (helps preserve water)
- Oxytocin INITATES Muscle contraction in Uterus and Stimulates Ejection of milk during Lactation
- Physical activity provides a potent STIMULUS for ADH secretion to help conserve body fluids
- The effect of short-term physical activity on oxytocin release remains UNKNOWN.
