control of hormone secretion and the endocrine system during exercise Flashcards
most hormones controlled by what?
negative feedback systems
most hormones are not secreted at a what?
constant rate
secretion is regulated by three different methods, what are they?
- The action of a substance other than a hormone on an endocrine gland. (humoral)
- Neural control of endocrine gland.(neural)
- Control of secretory activity of one endocrine
gland by hormone or neurohormone secreted by another endocrine gland. (hormonal)
Control by Humoral stimuli with PTH
Low blood Ca^2+-endocrine cell when blood Ca^2+ is too low-PTH-Osteoclast-increased blood Ca^2+
control by humoral stimuli without PTH
High blood Ca^2+ -endocrine cell when blood Ca^2+ is too high-no PTH is secreted-decreased blood Ca^2+
control by Neural stimuli part 1
An action potential (AP) in a neuron innervating an endocrine cell stimulates secretion of a stimulatory neurotransmitter.
control by Neural stimuli part 2
The endocrine cell secretes its hormone into the blood where it will travel to its target.
control by Neural stimuli part 3
An AP in the neuron stimulates secretion of an
inhibitory neurotransmitter.
control by Neural stimuli part 4
The endocrine cell is inhibited and does not secrete its hormone.
control by Hormonal stimuli part 1
Neurons in the hypothalamus release stimulatory hormones, called releasing hormones. Releasing hormones travel in the blood to the anterior pituitary gland.
control by Hormonal stimuli part 2
Releasing hormones stimulate the release of tropic hormones from the anterior pituitary, which travel in the blood to their target endocrine cell.
control by Hormonal stimuli part 3
The target endocrine cell secretes its hormone into the blood, where it travels to its target and produces a response.
control by Hormonal stimuli part 4
The hormone from the target endocrine cell also inhibits the hypothalamus and anterior pituitary from secreting the releasing hormone and the tropic hormone. This is negative feedback.
control by Hormonal stimuli part 5
In some instances, the hypothalamus can also secrete inhibiting hormones, which prevent the secretion of anterior pituitary tropic hormones.
Regulation of blood hormone levels (Negative feedback hormones) part 1
The anterior pituitary gland secretes a tropic hormone, which travels in the blood to the target endocrine cell.
Regulation of blood hormone levels (Negative feedback hormones) part 2
The hormone from the target endocrine cell travels to its target.
Regulation of blood hormone levels (Negative feedback hormones) part 3
The hormone from the target endocrine cell also has a negative-feedback effect on the anterior pituitary and hypothalamus and decreases secretion of the tropic hormone.
Regulation of blood hormone levels (positive feedback hormones) part 1
The anterior pituitary gland secretes a tropic hormone, which travels in the blood to the target endocrine cell.
Regulation of blood hormone levels (positive feedback hormones) part 2
The hormone from the target endocrine cell travels to its target.
Regulation of blood hormone levels (positive feedback hormones) part 3
The hormone from the target endocrine cell also has a positive-feedback effect on the anterior pituitary and increases secretion of the tropic hormone.
Hormone= Epinephrine
stimulant for release= moderate to intense exercise, stress, hypotension
Target tissue=skeletal muscle
Response= +Glycogenolysis(breakdown of glycogen), vasoconstriction
hormone= Norepinephrine
stimulant for release= moderate to intense exercise, hypoglycaemia
target tissue= adipose tissue, liver
response= +lipolysis (breakdown of fat),
+ heart rate,
+ glycogenolysis
hormone= Growth Hormone (GH)
Stimulant for release= exercise, hypoglycaemia
target tissue= skeletal tissue, bone, adipose tissue, liver
Response= stimulation of growth, FFA mobilization,
+ gluconeogenesis,
- glucose uptake
hormone= Testosterone
Stimulant for release= +FSH
+ LH
exercise, stress
target tissue= skeletal muscle, bone
Response= Protein synthesis, sperm production, sex drive
hormone= Estrogen
Stimulant for release= +FSH
+ LH
light to moderate exercise
target tissue= skeletal muscle, adipose tissue
Response= inhibition of glucose uptake, fat deposition
hormone= cortisol
Stimulant for release= ACTH, intense prolonged exercise
target tissue= skeletal muscle, adipose tissue, liver
Response= +Gluconeogenesis,
+ protein synthesis,
- glucose uptake
hormone= Insulin-like growth factor (IGF-1)
Stimulant for release= +GH
target tissue= almost all cells
Response= stimulation of growth
hormone response to exercise
Hormone concentrations
increase during exercise
Greater increases during
higher exercise intensities
Smaller increases in trained people
Except insulin which
decreases with exercise and
less in trained
overtraining and hormones
Hormonal evaluation is useful for monitoring sports training
Excessive frequency, volume and intensity of training, resulting in fatigue
testosterone to cortisol ratio is used to detect overtraining syndrome:
◦ Reflects the anabolic/catabolic status of the body
◦ Ratio decreases when training load increases
◦ Below a certain threshold, it may indicate over-training
◦ May be caused by both mental and physical stress
