Week 8 Flashcards
The endocrine system is a collection of what?
Glands
What does the endocrine system help differentiate?
Reproductive system and CNS in fetus
What does the endocrine system stimulate?
Growth and development
What does the endocrine system coordinate?
Male and female reproductive systems
What does the endocrine system provide maintenance to?
Internal environment
What does the endocrine system have adaptations to?
Emergency demands of the body
What is regulated in endocrine signaling?
Secretion of an extracellular signaling molecule (hormone) into ECF
What is there diffusion of in endocrine signaling?
Hormone into the circulation
What does the hormone diffuse out of in endocrine signaling?
Vasculature to the ECF and binding to a specific receptor on the target organ
What does one hormone regulate?
Activity of several target organs
What are the receptors for on target organs?
Multiple hormones
What are general characteristics of hormones?
Specific rates and rhythms of secretion
Operate within feedback systems
Affect only target cells with appropriate receptors
Are excreted by kidneys or deactivated by liver
Hormones are released in response to what?
Alteration in the cellular environment
Why are hormones released?
To maintain a regulated level of certain substances
What are hormones regulated by?
Chemical, hormonal, or neural factors
What can sensitivity of target tissue be regulated by?
Change in the number of affinity of receptors (up regulation or down regulation)
Somatotropes
Growth hormone
Corticotropes
Adrenocorticotropin (ACTH)
Thyrotropes
Thyroid stimulating hormone (TSH)
Gonadotropes
Luteinizing hormone and Follicle stimulating hormone
Lactotropes
Prolactin (PRL)
Posterior pituitary hormone is synthesized with their binding proteins where?
In the supraoptic and paraventricular nuclei of the hypothalamus
What is secreted by the posterior pituitary hormone?
Antidiuretic hormone (ADH)
Oxytocin
What does the antidiuretic hormone control?
Plasma osmolarity
Where is the antidiuretic hormone formed?
Supraoptic nuclei
What does oxytocin control?
Uterine contractions and milk ejection in lactating women
Where is oxytocin formed?
PVN
What is pituitary secretion controlled by?
Hormonal and neural signals from the hypothalamus
What is the posterior pituitary controlled by?
Nerve signals originating from the hypothalamus
What is the anterior pituitary controlled by?
Hypothalamic release and hypothalamic inhibitory hormones
How do the hypothalamic hormones reach the anterior pituitary?
Through the hypothalamic-hypophysial portal vessels
What are endocrine diseases classified into?
Primary - damage to gland
Secondary - damage to pituitary
Tertiary - damage to hypothalamus
What is produced in response to GH?
IGF-1
What does IGF-1 stimulate?
Chondrocytes
What is the structure of IGF-1 similar to?
Insulin
What does IGF-1 inhibit?
GH secretion
What does GH play a dual role in?
Metabolism
During the fed state GH promotes what?
Growth and protein anabolism
During the fasted state GH switches what?
Fuel consumption to lipids and sparing glucose
What are factors that stimulate GH release?
Glucose decrease
Free fatty acid decrease
Amino acid increase
Fasting
Stress
Exercise
Puberty
Androgens and estrogens
Sleep
What are factors that inhibit GH secretion?
Somatostatin
Glucose increase
Free fatty acid increase
Somatomedins
GH
Senescence
Obesity
Where are the lobes of the thyroid gland?
2 on either side of trachea
What do the follicle cells surround?
Colloid
What do Parafollicular cells (C cells) secrete?
Calcitonin
What does the thyroid hormone secrete for regulation?
Thyrotropin-releasing hormone and thyroid-stimulating hormone
What is the thyroid hormone secreted in response to?
Thyroid stimulating hormone
What percentage of thyroid hormone is T4?
90%
What percentage of thyroid hormone is T3?
10%
What does thyroid hormone affect?
Growth and maturation of tissues, cell metabolism, heat production, and oxygen consumption
Where is the adrenal glands located?
Close to the upper pole of each kidney
What are the two glands of the adrenal gland?
Adrenal medulla
Adrenal cortex
What percentage of adrenal glands total weight is the adrenal medulla?
20%
What is the adrenal medulla innervated by?
SNS
What percentage of weight of the adrenal gland is the adrenal cortex?
80%
What is the overall goal of the sympathorenal repose to exercise?
To meet the increased energy demand for both skeletal and cardiac muscles
What are phenochromocytoma?
Catecholamine secreting tumors
Where do phenochromocytoma arise from?
Chromaffin cells of adrenal medulla
What are phenochromocytoma the most common cause for?
Hyperfunctioning adrenal medulla
What are symptoms of excessive catecholamine release?
Sporadic rather than continuous
What does the zona fasciculata produce?
Cortisol
Why do cells in the zona fasciculata have a foamy cytoplasm?
They are filled with lipid droplets that store cholesterol esters
What is cortisol transported by?
Blood
How can cortisol be reversible inactivated?
By conversion to cortisone
What does cortisol maintain?
Blood glucose levels and CNS functions during fasting
When does cortisol increase blood glucose levels?
During stress at the expense of muscle protein
What does cortisol protect the body against?
Inflammation
What does cortisol inhibit?
Reproductive function (to conserve energy)
How does cortisol potentiate the effects of catecholamines?
Increasing adrenergic receptor expression
How does cortisol increase RBC production?
Stimulating EPO synthesis
What can stimulate CRH and ACTH release?
Neurogenic or systemic stress
When does the zona reticularis appear?
5 yo
How long do androgen levels continue to rise and peak?
Until mid 20s and then decline with age
What can DHEA be converted into?
Active androgens in both sexes
In what gender do adrenal androgens contribute me more?
Females
What is congenital adrenal hyperplasia?
When cortisol synthesis is blocked and so ACTH and adrenal androgens increase
What is the main product of zona glomerulosa?
Aldosterone
What does the zona glomerulosa increase?
Renal reabsorption of Na+ and excretion of K+
What does excess aldosterone cause?
Hypokalemia and muscle weakness
What does aldosterone deficiency cause?
Hyperkalemia
What affect does aldosterone have in the cardiovascular system?
Negative affect
What increases aldosterone?
Increased ECF of K+
Increased angiotensin 2
What decreases aldosterone?
Increased ECF of Na+
What is both of endocrine and exocrine gland?
Pancreas
What does the pancreas house?
Islets of langerhans
What does the pancreas secrete?
Glucagon and insulin
What are cells in the pancreas?
Alpha- glucagon
Beta- insulin
Delta
F cells
When is insulin released in the body?
When glucose is too high
When is glucagon released in the body?
When glucose is too low
When do serum insulin levels rise?
Within 10 min after eating and a peak of 30-45 min
Early phase of insulin release
Insulin secretion rising rapidly within 10 min
Late phase of insulin release
Slowly rises over a period of an hour
What is lost in patients with diabetes?
Distinction between early and late phases of insulin release
What does oral glucose stimulate the secretion of?
Glucose dependent insulinotropic peptide
Glucagon peptide 1 (both called incretins)
What does insulin promote in the muscles?
Glucose uptake
Glycogen synthesis
Glycolysis
Protein synthesis
