KIN 310 Cell Signaling and Hormonal Response to Exercise

Neuroendocrine system

Endocrine system releases hormones. Nervous system uses neurotransmitters

Endocrine glands

Release hormones directly into the blood

Hormones

After the activity of tissue that possess receptors to which the hormone can bind. Several classes based on chemical makeup. Amino acid derivatives. Peptides/protein. Steroids

Hormone

endocrine signal is released into the blood where it circulates to the tissue to have an effect

Neurotransmitter

use synaptic signals to relay messages. Relay messages from one nerve to the other, or from nerve to a tissue

Peptide

Amino acid chains. Insulin. Glucagon. Ghrelin. Leptin. Growth hormone. Thyroid stimulating hormone

Steroid

4 fused carbon rings. Estrogen. Testosterone. Progesterone. Cortisol

Factors influencing the effect of hormones have

The effect of a hormone on a tissue is determined by the plasma concentration. Determined by: Rate of secretion of hormone from endocrine gland. Magnitude of input. Rate of metabolism (inactivated) or excretion (removal) of hormone. At the receptor and by

Rate of secretion of the hormone from the endocrine gland

Influenced by the magnitude of stimulatory or inhibitory signals on the endocrine gland

Metabolism or excretion of hormones

Removal of hormones from the system. Kidney excretion. Liver metabolism

Plasma volume

By changing plasma volume (mostly water and dissolved proteins) that will alter hormone concentration without changing secretion or metabolism/excretion

How hormones work

Hormones only affect tissue with specific receptors. Receptors are not static fixtures." Magnitude of effect dependent on. Concentration of the hormone. Number of receptors on the cell. Affinity of the receptors for the hormone

Downregulation

A decrease in a cellular component. Decrease in receptor number in response to high concentration of hormone

Uppregulation

An increase in a cellular component. Increase in receptor number in response to low concentration of hormone

Cyclic AMP "second messenger" mechanism

Examples include: Breakdown of glycogen to glucose. Breakdown of triglycerides to FFA. This process is inactivated by phosphodiesterase. Phospholipase C second messenger mechanism

Gland specific hormones

Hypothalamus (Anterior & Posterior Pituitary Gland). Thyroid Gland. Parathyroid Gland. Adrenal Gland. Pancreas. Testes & Ovaries

Adrenocorticotropic hormone (ACTH)

Secretion of cortisol

Follicle-stimulating hormone (FSH)

Stimulate ovulation (women) or sperm production (men)

Luteinizing hormone (LH)

Stimulates production of testosterone and estrogen

Melanocyte-stimulating hormone (MSH)

Stimulates skin/hair growth as well appetite

Thyroid-Stimulating hormone (TSH)

Rate of thyroid hormone secretion

Growth hormone

stimulates IGFs (negative feedback loop)

Prolactin

stimulates the production of breast milk

Growth hormone and performance

GH increases protein synthesis in muscle and long bone growth. Use to treat childhood dwarfism. Also used by athletes and elderly. More adverse effects then benefits. No evidence that GH promotes strength gains. Minimal strength gains compared to resistan

Posterior pituitary gland

oxytocin and antidiuretic hormone

Oxytocin

Smooth muscle stimulator during birth. Milk release during breast feeding

Antidiuretic hormone

Reduces water loss from the body. Does exactly what the name implies. Favors the reabsorption of water from the kidneys tubules back into the capillaries to maintain body fluid

Thyroid Gland

T3 and T4 (iodine hormones) are released into circulation. Number refers to the atoms. Bound to plasma protiens for transportation. They need to separate from these proteins and become "free" to have an effect on tissue. Low T3= hypothyroid. Linked to wei

Parathyroid gland

Involved in plasma Ca++ regulation. Releases parathyroid hormone

Adrenal medulla

Catecholamine. Epinephrine. Norepinephrine. Blood pressure and substrate utilization

Adrenal cortex

Steroid hormones. Mineralocorticoids. Maintain sodium and potassium concentration. Glucocorticoids. Involved in plasma glucose regulation. Sex steroids

Mineralocorticoid (adrenal cortex)

Aldosterone. Control of Na+ reabsorption and K+ secretion. Na+/H2O balance. Regulation of blood volume and blood pressure (deliver oxygen). Part of renin angiotensin aldosterone system (released during exercise). All three hormones increase during exercis

Renin angiotensin aldosterone system

1. A decrease in plasma (water part) volume, a fall in BP at the kidney, or an increase in SNS activation to the kidney will stimulate the kidney to release Renin
Decrease in volume or sympathetic activation. 2. Renin enters the plasma and converts renin

Glucocorticoid

Maintain plasma glucose. Promote breakdown of tissue protein by inhibiting protein synthesis to form amino acids which are then used by the liver to form new glucose. Stimulate the mobilization of free fatty acids. Stimulate liver enzymes involved in the

Pancrease

insulin, glucagon, somatostatin

Insulin (?)

Stimulates glucose and amino acid uptake into cells. A lack of insulin causes an accumulation of glucose in the plasma and can lead to diabetes mellitus. Hyperglycemia (taking an insulin shot)

Glucagon (?)

Mobilize glucose from liver stores and fatty acids from adipose tissue. Use adenylate cyclase second messenger system. Exerts effects opposite if insulin

Somatostatin (?)

Controls the rate of entry of nutrient molecules into circulation in the GI tract

Insulin receptor

Glute 4 channels open. Once the insulin gets in it tells the glute 4 channels to open to increase glucose level

Testosterone

Released from testes promotes protein synthesis. Anabolic steroid. Androgenic.

Anabolic steroid

Promotes tissue (muscle) building. Performance enhancement

Androgenic steriod

Promotes masculine characteristics

Estrogen and progesterone

Released from ovaries. Establish and maintain reproductive function. Levels vary throughout the menstrual cycle

Follicular phase

When follicles in the ovary mature. Ends with ovulation

Luteal phase

After ovulation when the lining of the uterus thickens

How to use fuel

Largely dependent upon duration and intensity. Strenuous Exercise = CHO oxidation. Prolonged, Moderate Exercise = Fat oxidation, as CHO are depleted.

Muscle glycogen utilization

The heavier the exercise the faster glycogen breakdown occurs. This breakdown is initiated by second messengers, which activate protein kinases in the muscle cell. Plasma epinephrine is a powerful stimulator of glycogenolysis (breaking down glycogen into

Glycogen utilization

high intensity reduces glucagon quickly. Epi increase glycogen is increasing. When a drug blocks the ? receptors, glycogenolysis can still occur. Glycogen to glycolysis doesn't use ATP. Glucose to G6P, hexokinase (transferase)

Blood glucose homeostasis during exercise

Plasma glucose concentrations are maintained by 4 main processes. THE BODY WANTS TO SPARE BLOOD GLUCOSE...IT DOES NOT WANT TO USE. THIS FUEL SOURCE. Hormonal control of blood glucose acts in 2 ways (slow acting and fast acting)

mobilization glucose

from liver glycogen to maintain plasma glucose levels

mobilizing plasma FFa

from adipose tissue to spare plasma glucose

synthesizing new glucose

in the liver from amino acids, lactate, and glycerol

blocking glucose entry

into cells to force the substitution of FFA as fuel and thus spare glucose

Slow acting

Thyroid hormone. Cortisol . Growth hormone. Slow acting are slow because they need to penetrate the cell membrane and enter the nucleus of the cell

Fast acting

Epinephrine and norepinephrine. Insulin and glucagon. Fast acting only have to attach to the cell membrane to initiate their effect

Thyroid hormone

T3 & T4 are important for establishing the overall metabolic rate and allow other hormones to exert their full effect . They influence the # of receptors on the surface of a cell or the affinity of the receptor for the hormone (What is this called? Up reg

Cortisol "stress hormone

Released when there is low plasma [glucose]. Stimulates FFA mobilization from adipose tissue. Mobilizes tissue protein to yield amino acids for glucose synthesis in the liver. Decreases the rate of glucose utilization by cells. Light Ex = cortisol is remo

Growth hormone supports the action of cortisol

wants to preserve plasma glucose. Protein synthesis. Decreases glucose uptake by tissues. Increases FFA mobilization. Enhances gluconeogenesis in the liver

Norepinepherine

plasma levels are indicative of sympathetic nervous system activity

Epinephrine

primary catecholamine in mobilization of glucose from the liver, and FFA from adipose tissue

Epinephrine and norepinephrine

1. Mobilization of glucose from the liver
2. Mobilization of FFA from adipose tissue
3. Interference with the uptake of glucose by tissues

Insulin

Uptake and storage of glucose and FFA. Plasma concentration decreases during exercise. Decreased insulin response following training. secretion influenced by catecholamine

Glucagon

Mobilization of glucose and FFA fuels. Plasma concentration increases during exercise. Decreased response following training. secretion influenced by catecholamine