Endocrine SHIZZLE Flashcards
Endocrine vs Exocrine
Endocrine: ductless, hormones into bloodstream, hormones only act on target cells
Exocrine: secrete externally via ducts or tubes, deliver product directly to a specific site
Paracrine vs. Autocrine Secretion
Paracrine: affect nearby cells via messenger molecule
Autocrine: affect cells that secrete the substance
Nervous System vs. Endocrine System
Cells: Neurons vs Glandular epithelium
Chemical signal: Neurotransmitter vs. Hormone
Specific action: Receptors on postsynaptic cell, receptors on target cell
Speed of onset: seconds, seconds to hours
Duration of action: very brief, brief or even days
Endocrine Chemical Communication
- Endocrine system is precise, in that only target cells can respond to a specific hormone
- Target cells contain particular receptors for the hormone; these receptors are not present on other cells
Steroid Hormone General Information
- lipids containing aromatic rings
- produced from cholesterol
- ex: sex hormones (testosterone, estrogens) & adrenal cortex hormones (cortisol, aldosterone)
Non-Steroid Hormone General Information
- Amines: Derived from tyrosine (–epinephrine, norepinephrine)
- Proteins: Composed of long chains of amino acids (growth hormone, PTH, GH PRL)
- Peptides: Short chains of amino acids (oxytocin, ADH, TRH, SS)
- Glycoproteins: Carbohydrates joined to proteins (TSH, FSH, LH)
Actions of Hormones
- Deliver messages by binding to specific receptors on/in target cell
- Number of receptors determines strength of response, and can be altered (upregulation and downregulation)
Steroid Hormone Mechanism
1) Steroid hormone crosses into cell membrane due to likeness of cholesterol
2) Combines w/ protein receptor usually found inside the nucleus
3) Hormone-receptor complex binds to DNA and synthesizes mRNA
4) mRNA leaves nucleus and translation leads to synthesize of proteins as instructed by hormone
Non-Steroid Hormone Mechanism
1) Non-steroid hormone binds to specific receptor molecule on cell membrane
2) Activates adenylate cyclase
3) Catalyzes conversion of ATP into cAMP
4) cAMP activates proteins, causing a series of reactions leading to cellular changes associated with hormone’s action
Prostaglandins
- Paracrine substance
- Can activate or inhibit adenylate cyclase > controls cAMp production, therefore alters a cell’s response to hormones
Negative Feedback
-Control mechanism in which rising level of a hormone leads to a decrease in hormone secretion and vice versa
stimulus > receptors > gland > effector > response
3 Methods in which negative feedback controls hormone secretion
1) Tropic Hormones: act on other glands to regulate their secretion
2) Nervous System Control: NS stimulates some glands to secrete hormones via nerve impulses
3) Changes in composition of internal environment: changing levels of specific substances in blood can either inhibit/stimulate secretion of some hormones
Anterior Pituitary Lobe Regulation vs Posterior Pituitary Lobe Regulation
-Anterior Lobe Regulaton:
Hypothalamic releasing hormones are transported through the Hypophyseal Portal System, and stimulate cells of anterior lobe to release hormones
-Posterior Lobe Regulation:
Nerve impulses from the hypothalamus travel through the infundibulum, and stimulate nerve endings in posterior lobe to release hormones
Anterior Pituitary Hormones
Growth hormone (GH) Prolactin (PRL) Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH)
Posterior Pituitary Hormones
Antiduretic Hormone (ADH) Oxytocin (OT)
Thyroid Gland Hormones
Thyroxine - increases rate of energy release from sugars/protein synthesis
Triiodothryronine - “ x5
Calcitonin - lowers blood calcium by increasing rate of bone deposition
Parathyroid Gland Hormones
PTH - increases blood calcium by breaking down bone faster
Adrenal Medulla
Epinephrine (Adrenaline)
Norepinephrine (Noradrenaline)
Adrenal Cortex
Aldosterone
Cortisol
Adrenal androgens
Renin-Angiotensin System
1) Low blood pressure/sodium concentration releases renin
2) Renin activates Angiotensin I which is converted into Angiotensin II
3) Angiotensin II stimulates secretion of aldosterone
4) Aldosterone acts on kidney to conserve sodium and water (via osmosis)
5) Blood pressure returns to normal
Pancreas cells
- Alpha cells secrete glucagon
- Beta cells secrete insulin
- Delta cells secrete somatostatin
Glucagon
- stimulates liver to break down glycogen and convert noncarbohydrates into glucose
- stimulates breakdown of fats
Insulin
- promotes formation of glycogen from glucose
- promotes movement of glucose into certain cells
- decreases blood glucose concentration
- enhances synthesis of proteins/fats
Somatostatin
-Helps regulate carbohydrates
Stimulus, Receptor, Control Center, Effector, Response: Blood glucose concentration too high
Stimulus: Rise in blood glucose
Receptor: Beta cell receptors detect a rise in glucose
Control center: Beta cells secrete insulin
Effector: Insulin stimulates formation of glycogen from glucose, promotes movement of glucose into certain cells
Response: Blood glucose levels drop
Stimulus, Receptor, Control Center, Effector, Response: Blood glucose concentration too low
Stimulus: Drop in blood glucose
Receptor: Alpha cell receptors detect drop in blood glucose
Control Center: Alpha cells secrete glucagon
Effector: glucagon stimulates formation of glucose from glycagon, converts noncarbohydrates into glucose
Response: blood glucose levels rise
Glucagon signaling cascade
-acts as non-steroid hormone to increase cAMP, leading to degradation of glycogen to glucose
Type I Diabetes Mellitus
- insulin dependent
- juvenile onset
- thin
- cause: increased blood glucose, no insulin
- treated with insulin injections
Type II Diabetes Mellitus
- Non-insulin dependent
- fatties
- causes: results from insulin insensitivity
- elevated insulin levels, increased glucose levels
Stress
“A condition or feeling experienced when a person perceives that demands exceed the personal and social resources the individual is able to mobilize.”
Responses to Stress: “Fight or flight”
- Blood glucose/glycerol increases
- Heart rate/blood pressure/breathing increases
- pupils/air passages dilate
Responses to Stress: Resistance/Long-term adjustment
- increase in:
- blood concentration of amino acids
- release of fatty acids
- glucose (from noncarbohydrates)
Consequences of Stress
- Consequences: anxiety, insomnia, muscle pain, high blood pressure and a weakened immune system
- -blood pressure, heart rate, vascular tone (or vein constriction), inflammation, and accelerated blood clotting
- Health effects: heart disease, depression and obesity
Pineal gland
- secretes melatonin
- regulates circadian rhythms
Thymus gland
- secretes thymosins
- promotoes development of certain lymphocytes
- important role in immunity
Reproductive organs
- Ovaries produce estrogen and progesterone
- Testes produce testosterone
- Placenta produces estrogens, progesterone, and gonadotropin
