neuroendocrine system Flashcards
general adaption syndrome
- Alarm phase (adrenal medulla)
- Resistance phase (adrenal cortex)
- Recovery phase
Alarm phase
- activation of the amygdala (fight or flight response)
- activation adrenal medulla (SNS)
activation of adrenaline
activation of adrenergic receptors
increase bp, blood glucose and respiratory
circulation to brain, lungs and skeletal muscles
= escape from dangerous stimulus
The adrenal gland consists of
capsule zona glumerulosa zona fasciculata zona reticularis adrenal medulla
adrenal gland hormones
- aldosterone
- cortisol
- epinephrine
Adrenal medulla
- produces catecholamine - makes ephrinephanine
- water-soluble - rapid secretion
- secreted into the large vein which drains into vena cava
- acts via adrenic reception ( a and B)
a1 adrenergic receptors
located in
- blood vessels
- radial muscle of the iris
- sphincters
- smooth muscle of GIT
- hepatocytes
_ increases in Bp
- pupil dilation
- decreased GIT mobility
- increases BGL gluconeogenesis (formation), glycogenolysis) .
A2 adrenergic receptors
located in
- peripheral sympathetic nervous system
- platelets
- adipose tissue
- central nervous system
- decrease of insulin + glucogon secretion
- decrease lipolysis
- Platelet aggregation
- decrease of neurotransmitter release
B1 adrenergic receptors
located in
- myocardium
- adipocytes
- smooth muscles of GIT
Positive inotropic, chronotropic, dromotropic effects on the heart (force levels)
Increases lipolysis
Increase BP
B2 adrenergic receptors
located in
- smooth muscle of bronchioles
- skeletal muscles
- mast cells
- uterus
- hepatocytes
- pancreas
- Decreased GIT mobility, bronchiolar contractility, uterine contractility
- Increased BGL, insulin/glucagon release, lipolysis, K+ uptake and peripheral T4 to T3 conversion
Resistance to adrenergic receptors
- prolonged stressor application
- secretion of cortisol from the adrenal cortex
- maintains higher blood glucose (gluconeogenesis)
Cortisol
- transported bound to transcortin/albumin
- follows circadian rythym
- increases antagonism of insulin and stimulates glycogenesis
- increases BP via vasoconstriction
Glucocorticoid receptors
- in the brain (neg. feedback behaviour)
- Liver, adipose tissue, skeletal tissue (metabolic effects)
- Heart, blood vessels (cardiac function, bp, immune function)
What is exhaustion?
- resources of the body become depleted
- prolonged exposure to resistance leads to
wasting of muscle
suppression of the immune system
failure of pancreatic beta cells
damage to vital organs
Pineal gland and melatonin
- small gland in the brain
- melatonin = body temp, appetite and sleep. Peaks at night and dow during day.
main types of nutrients
- water
- carbohydrates
- lipids
- proteins
- minerals
- vitamins
metabolism
all the chemical reaction of the body
enzymes
- catalyse chemical reactions
- may require co-enzymes
anabolic reactions
- synthesis or binding reactions
- endergonic - energy consuming
catabolic reactions
- decomposition reactions
- exergonic - produce more energy than consumed
catabolism and anabolism
- provides energy for the synthesis of other bonds
- drives other anabolic reactions
- anabolic reaction of ADP + a phosphate to produce ATP
what happens to ingested carbohydrates
- catabolised to monosaccharide
- glucose
- fructose
- galactose
After absorption monosaccharides are - used to synthasie ATP, converted to glycogen and store.
glucose anabolism
Glycogen
- storage form of carbohydrates
- synthesis stimulated by insulin
gluconeogenesis
- synthesis of new glucose molecules from protein and lipid decomposition
fat catabolism
- lipolysis
- hormones that enhance lipolysis = adrenaline, noradrenaline, cortisol
fat anabolism
- insulin stimulates the liver and adipose cells to synthesize triglycerides
- all excess food types can be converted to triglycerides
- other lipids produced: phospholipids, lipoproteins, myelin sheaths.
Lipoproteins
- transport lipid in blood
- largest and lightest to smallest and heaviest
Chylomicrons (lipoproteins)
- carried by lymph to blood
- transport lipids to adipose
Very low-density lipoproteins (ULDL’s)
- transport triglycerides to adipose
- converted to LDLS
Low-density lipoproteins (LDL’s)
- transport 75% of cholesterol to cells
- deposit cholesterol to smooth muscles and arteries
High-density lipoproteins
- transport cholesterol from body cells to liver for elimination
What happens to ingested proteins?
- amino acids not stored as proteins
- used to synthesize
ATP
structural proteins
enzymes
replace damaged proteins
antibodies
transporter
protein catabolism
- protein breakdown occurs regularly
protein anabolism
- formulation of peptide bonds to synthesize proteins
Amino acids
20 amino acids
10 essential - present in the diet
10 - synthesized by body
Why are vitamins important?
- most cannot be synthesized by the body
- important for specific metabolic pathways
Minerals
- help regulate enzymatic reactions or act as co-enzymes
- incorporation into structures
