Hormones, Exercise, & Training Flashcards
What 3 components characterize the endocrine system
- host gland
- hormones
- target (receptor) cells or organs
What does the host gland do
- secrete hormones
- lack ducts but discharge their substances directly into the extracellular space around the gland
Describe hormones
- a chemical secreted by a cellar group of cells into the blood for transport to a distant target, where it exerts its effect at low concentrations
How can hormones be classified
- by their sources
- their receptor type
- their chemical structure
How do hormones function
- most hormones combine with a specific receptor molecule on the cell surface causing the cell to discharge a second chemical that initiates a cascade of cellular events
What are the 4 mechanisms that hormone actions occur
- changing the synthesis rate of intracellular proteins
- altering enzyme activity
- modifying cell membrane transport
- inducing secretory activity
What 3 factors determine a hormone’s plasma concentration
- sum of synthesis and release by the host gland
- rate of receptor tissue uptake
- rate of removal from the blood by the liver and kidneys
Describe growth hormone
- promotes cell division & proliferation throughout the body
How does growth hormone facilitate protein synthesis
- increasing amino acid transport through plasma membranes
- stimulating RNA formation
- activating cellular ribosomes that increase protein synthesis
Describe growth hormone relating to exercise
- secretion increases a few minutes after exercise begins
- relates more closely to peak exercise intensity rather than duration or total exercise volume
How is cortisol released
- hypothalamus secretes corticotropin-releasing hormone which is transported to the anterior pituitary & stimulates the release of corticotropin, which acts on the adrenal cortex to promote synthesis & release of cortisol
Describe ACTH related to exercise
- ACTH concentrations increase with exercise duration if intensity exceeds 25% of aerobic capacity
What are the two types of gonadotropic hormones
- follicle stimulating hormone (FSH)
- luteinizing hormone (LH)
What does follicle stimulating hormone (FSH) do in females
- initiates follicle growth in the ovaries & stimulates ovarian secretion of estrogens
What does follicle stimulating hormone and luteinizing hormone in combination do in females
- stimulates estrogen secretion & initiates rupture of the follicle to allow the ovum to pass through the fallopian tube for fertilization
What does follicle stimulating hormone do in males
- stimulates germinal epithelial growth in the testes to promote sperm development
What does luteinizing hormone do in males
- stimulates the testes to secrete the hormone testosterone
What hormones come from the anterior pituitary
- growth hormone
- corticotropin
- follicle stimulating hormone
- luteinizing hormone
What hormones come from the posterior pituitary
- antidiuretic hormone
- oxytocin
How does the posterior pituitary release hormones
- it does not synthesize its hormones, it receives them from the hypothalamus for release to the general circulation via neural stimulation
What does antidiuretic hormone do
- it limits how much urine the kidneys produce
What does oxytocin do
- it stimulates uterine muscle activity & milk ejection from the breasts during lactation
Describe antidiuretic hormone relating to exercise
- exercise is a potent stimulus for antidiuretic hormone secretion, which increases water reabsorption by the kidney tubules during & after exercise
What hormones are released by the thyroid
- calcitonin
- thyroxine
- triiodothyronine
What stimulates the release of thyroid hormones
- thyroid stimulating hormone released by the anterior pituitary gland stimulates the thyroid gland to release its hormones
Function of thyroid hormones
- they provide essential stimulation for normal growth & development, especially of nerve tissue
What hormone does the parathyroid secrete
- secretes parathyroid peptide hormone (PTH) to increase plasma Ca++ concentration
What 3 ways does parathyroid peptide hormone increase plasma Ca++ concentration
- mobilizes Ca++ from bone
- enhances renal Ca++ reabsorption
- indirectly increases intestinal Ca++ absorption by its influence on vitamin D3
Describe adrenal glands
- located above each kidney
- inner portion is the adrenal medulla
- outer portion is the adrenal cortex
- both secrete different hormones
What does the adrenal medulla do
- it prolongs & augments sympathetic neural effects by secreting epinephrine & norepinephrine
What factors determine catecholamine response to exercise
- exercise intensity
- exercise duration
- age
- gender
What does the adrenal cortex do
- secretes adrenocortical hormones in response to ACTH stimulation from the pituitary gland
What does increased cortisol secretion from the adrenal cortex do
- decreases glucose uptake in many tissues
- decreases amino acid uptake in many tissues
- increases adipose tissue synthesis
- increases protein breakdown
- decreases protein synthesis
- increases gluconeogenesis
What are the 4 types of pancreatic hormones and what they do
Beta cells: produce insulin & amylin
Alpha cells: secrete glucagon
D cells: secrete somatostatin
PP cells: produce pancreatic polypeptide
What happen when you have high blood sugar
- Beta cells in the pancreas secrete insulin
- insulin stimulates glycogen formation in the liver to lower blood sugar
- insulin also stimulates glucose uptake from the blood to lower blood sugar
What happens when you have low blood sugar
- Alpha cells in the pancreas secrete glucagon
- glucagon stimulates glycogen breakdown in the liver to raise blood sugar
What factors stimulate insulin secretion after eating
- increased blood glucose concentrations
- increased blood amino acid concentrations
- gastrointestinal tract hormones
- parasympathetic nervous system stimulation
- sympathetic nervous system stimulation
What is insulin’s major function
- it regulates glucose metabolism by facilitating cellular glucose uptake in all tissues except the brain
How does insulin exert its action on glucose
- increases glucose transport into most, but not all, insulin sensitive cells
- enhances cellular utilization & storage of glucose
- enhances utilization of amino acids
- promotes fat synthesis
What happens when insulin secretion increases
- increase glucose uptake
- increase amino acid uptake
- increase protein synthesis
- decrease protein breakdown
- increase fatty acid & triacylglycerol synthesis
- decrease lipolysis
- increase glycogen synthesis
- decrease glycogenolysis
Define glycogenolysis
- breakdown of glycogen into glucose
Define lipolysis
- breakdown of lipid cells
What happens when glycogen secretion increases
- increase glycogenolysis
- decrease glycogen synthesis
- increase gluconeogenesis
- increase ketone synthesis
- decrease protein breakdown
- increase lipolysis
- decrease triaclyglycerol synthesis
Describe glucagon secretion relating to exercise
- contributes to blood glucose regulation during endurance exercise & starvation
- glucagon release is also stimulated by plasma amino acids
Cause of Type 1 diabetes
- results form the body’s failure to produce insulin
Cause of Type 2 diabetes
- is a relative insulin deficiency that results in hyperglycemia
Cause of gestational diabetes
- afflicts about 9% of all pregnant women
Cause of pre-diabetes
- is a condition where a person’s glucose reaches higher than normal levels but not high enough for a diagnosis of Type 2 diabetes
Environmental triggers for Type 1 diabetes
- cold weather exposure
- viral infection
- early diet
Testing for diabetes and current suspected diabetes value
- fasting plasma glucose test after an 8 hour fast
- fasting plasma glucose of suspected diabetes is >126 mg·dL^-1
Describe metabolic syndrome
- multifaceted grouping of coronary artery disease risks
- the clustering of insulin resistance & hyperinsulinemia
Risk factors for metabolic syndrome
Abdominal fatness: Men- >102 cm or >40 in; Women- >88 cm or > 35 in
Triacylglycerols: >150 mg/dL
High density lipoprotein: Men- <40 mg/dL; Women- <50 mg/dL
Blood pressure: >130/>85 mmHg
Fasting glucose: >110 mg/dL
Describe Type 1 diabetes and exercise
- must exercise with caution because of increased insulin sensitivity & because fast delivery of injected insulin via the rapid circulation with exercise accelerates glucose removal from plasma
Describe Type 2 diabetes and exercise
- regular physical activity for the Type 2 diabetic improves glycemic control, cardiovascular function, body composition, psychological profile, & reduces a broad array of heart disease risks
Describe endurance training and the endocrine function between a trained person & non trained person
- exercise at a particular absolute intensity produces a lower hormonal response in trained individuals compared to untrained
- with max exercise, trained individuals have a similar/slightly higher catecholamine & pituitary hormonal response the untrained inidivduals
Describe the effects of endurance training on endocrine function
- elevates hormone response during exercise for ACTH & cortisol
- depresses hormone response during exercise for GH, PRL, follicle stimulating hormone, luteinizing hormone, testosterone, ADH, T4, & insulin
Describe the effects of resistance training on endocrine function
- resistance training increases the frequency & amplitude of testosterone & growth hormone secretion
