describe the concept of hormone-receptor interaction
the hormone- recetorminteraction triggers events the cells. changes in the concentration of the hormone, the number of receptors on or in the cell and someone- receptors affinity all influcen the magnitude of the effect
recapture number decreae when increase level of hormone t
low hormone levels may lead to increase in receptors and increase senility
identify the factors influencing the concentration of a hormone in the blood
the hormone secretion rate form the endocrine gland
the rate of hormonal metabolism or excretion
transport protein quality ( lipid based hormones)
changes in the plasma volume
Describe the mechanisms by which hormones act on cells
- endorcrine glands releae hormones directly into the blodd to alter the activity of tisseus possessing hormonespecific receptros
- the free plasma hormone concetration determine the magnitude of the effect at the tissues level
- the three hromones concetration can be changed by altering the rate of secretion or inacitivtion of the hormone, the quantity of tranpost protein and the plasma volume
- th homrones - receptros interaction triggers events that
the hypothalamus controls the avitiy of both the anterior pituitary glands
- GH is released from the anterior pituraty gland and is essential for normal growth
- GH increases during exericse to mobilize fatty acids from adiopose tissue and to aid in the maintenance of blood glucose
thyroid homrones T3 and T4 are importnt for maintaing the metabolic rate and allowing other hormones to bring about their full effect
E and NE bind to alpha and betaer receptors and bring about changes in cellular acitity vis second messangers
describe the role of hypothalamus in the control of hormone secretion from the anterior and posterior pituitary glands
controls the activity
identify the site of release, stimulus for release, and the predominant action of the following hormones: E, NE, glucagon, insulin, cortisol, aldosterone, thyroxine, growth hormone, estrogen, testosterone
thyroid hormones T3 and T4 are importnatn for amintinag the metabolic rate and allowing other hormones to bring about their full effect
- see graph for other
Epinephrine (E) and Norepinephrine (NE)
Site of release: Adrenal medulla.
Stimulus for release: Increased sympathetic nervous system activity, often in response to physical or emotional stress, fear, or hypoglycemia (the “fight-or-flight” response).
Predominant action: Prepares the body for emergency action, increasing heart rate, blood pressure, and blood flow to muscles and the brain; also promotes glycogenolysis (breakdown of glycogen) and lipolysis to mobilize energy stores.
Glucagon
Site of release: Alpha cells of the pancreatic islets of Langerhans.
Stimulus for release: Low blood glucose concentration (hypoglycemia), prolonged fasting, or a protein-rich meal.
Predominant action: Increases blood glucose levels by stimulating the liver to perform glycogenolysis (breakdown of glycogen to glucose) and gluconeogenesis (synthesis of new glucose from other molecules like amino acids).
Insulin
Site of release: Beta cells of the pancreatic islets of Langerhans.
Stimulus for release: High blood glucose concentration (hyperglycemia), amino acids, and fatty acids after a meal.
Predominant action: Lowers blood glucose levels by stimulating the uptake of glucose into most body cells (especially muscle and adipose tissue) and promoting the storage of glucose as glycogen (glycogenesis) in the liver and muscles, and fat (lipogenesis) in adipose tissue.
Cortisol
Site of release: Adrenal cortex (specifically the zona fasciculata).
Stimulus for release: Adrenocorticotropic hormone (ACTH) from the anterior pituitary, which is itself stimulated by corticotropin-releasing hormone (CRH) from the hypothalamus in response to stress and a circadian rhythm.
Predominant action: Regulates metabolism of fats, proteins, and carbohydrates; increases blood glucose; suppresses the immune system and inflammation; helps the body respond to stress.
Aldosterone
Site of release: Adrenal cortex (specifically the zona glomerulosa).
Stimulus for release: Primarily the renin-angiotensin-aldosterone system (RAAS) activated by decreased renal blood flow or low sodium levels, and also directly by high potassium levels (hyperkalemia) in the blood.
Predominant action: Increases sodium reabsorption and potassium secretion in the collecting ducts of the kidney, which helps regulate blood pressure and electrolyte balance.
Thyroxine (T4 and T3)
Site of release: Thyroid gland (follicular cells).
Stimulus for release: Thyroid-stimulating hormone (TSH) from the anterior pituitary, which is stimulated by thyrotropin-releasing hormone (TRH) from the hypothalamus.
Predominant action: Maintains general metabolic rate in nearly all cells, affecting breathing, heart rate, digestion, and body temperature.
Growth Hormone (GH)
Site of release: Anterior pituitary gland.
Stimulus for release: Growth hormone-releasing hormone (GHRH) from the hypothalamus; also stimulated by low blood glucose, exercise, and stress.
Predominant action: Promotes growth of bone and soft tissues; increases protein synthesis and amino acid uptake; mobilizes fatty acids for energy.
Estrogen
Site of release: Ovaries (primarily).
Stimulus for release: Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary.
Predominant action: Development of female secondary sex characteristics and regulation of the menstrual cycle.
Testosterone
Site of release: Interstitial cells of the testes.
Stimulus for release: Luteinizing hormone (LH) from the anterior pituitary.
Predominant action: Development of male secondary sex characteristics and stimulation of sperm production, protein synthesis, and amino acid uptake.
discuss the use of testosterone (and its synthetic analogs) and growth hormones on muscle growth and their potential side effect
GH increases during exercise to mobilize FFA from adipose tissue and to aid in the maintenance of blood glucose
contrast the role of plasma catecholamines with intracellular factors in the mobilization of muscle glycogen during exercise
Plasma catecholamines mobilize blood glucose and FFA, while intracellular signals in the muscle itself (calcium, AMP, phosphorylase kinase) control the rate of muscle glycogen breakdown.
plasma glucose is maintained during exercse by increasing liver glucose mobilization using more plasama FFA, increasing glucogensisi, and decreasing glucose uptake by tissues. the decrease in plasma insulin and the increase in plasma E, NE, Gh, glucagon and cortisol during exercise control these mechansims to maintain the glucose concentration.
glucose is taken up to 7 to 10times faster during exercise than at rest - evne with the decrease in plasma insulin. the increaase in intraceullar Ca++ and other factors are associaed wtih an increase in the number of glucose trasnporters ithat increae the memebran transport of glucose
training causes a reduction cirulatoing levels of E Ne gluacagon and inslusin repsose to exercse
discuss the 4 hormonal mechanisms by which blood glucose homeostasis is maintained
mobilize exiting glucose from liver glycogen stoes
mobilize FFA from adipose tissue to increase the use of fat as a fuel and this spare plasma glucose
synthezise new glucose from animo acids, glycerol and lactate ( glycogenesis)
black glucose entry into cells ( an “anti-insulin”) effect, forcing the cells to use fat as a fuel and thus spare plasma glucose
graphically describe the changes in the following hormones during graded and prolonged exercise: insulin, glucagon, cortisol, growth hormone, E and Ne
as exercise intensity increase E increase
as increase Vo2max linearly increase plasma cortisol
increase VO2 max exponential increase in GH
increase Vo2 max decrease insulin
increase time spent exercising n crease glucagon for untrained but trained remains lower
describe the effect on changing hormone and substrate levels in the blood on the mobilization of free fatty acids from adipose tissue
the plasma FFA concentration decreased during heavy exercise even though the adopts cell is stimulated by a variety of hormones to increase triglyceride breakdown to FFA and glycerol. This outcome may be due to
1) the higher h+ concentration , which may inhibit HSL
20 the high levels of lactate during heavy exercise that promote the resynthesis of triglyceride
3) an inadequate blood flow to adipose tissue
4) insufficient albumin needed to traponsirt the FFA in the plasma
explain hormone control and exercise physiology
what role do endocrine pathways play in regulating exercise performance or aid in adapting to exercise to modify or maintain health
