Ch. 2 Chemical Messengers Flashcards
Name the two systems that coordinate cells and how each does it
o NS: control by nerve impulses
o Endo: release of chemical messengers (hormones)
Define Homeostasis
the maintenance of a relatively constant internal environment despite fluctuation in the external environment
What are the two types of glands
Ex/Endocrine
What is the difference between endocrine and exocrine glands
- Exocrine gland- secretes to ducts > surface or cavity
Endocrine gland- secretes to extracellular fluid > capillaries > transported by blood.
Why are endocrine referred to as ‘ductless’
released directly into blood
Name 8 major endocrine glands
- Hypothalamus
- Pituitary
- Thymus
- Adrenal gland
- Gonads (Ovaries and Testes)
- Pineal gland
- Thyroid gland/parathyroid
- Pancreas
Define hormone
a chemical secreted by an endocrine gland, and that affects functioning of a cell or organ
What are the three ways hormones affect cells
- Change shape of enzyme > changes rate of protein production
- Rate of transcription/translation > protein production
- Turn on/ off structural genes
What are the three factors that effect functioning of hormones
- Specific (lock and key): only influence cells with correct receptors
- Saturation: has max rate when all receptors are occupied
- Sensitivity: #/type of receptors on cells
What are the (Three) types of hormones
Paracrine, Protein and Amine, Steroid
Define paracrine and what are they also known as
>
any chemical secreted by a cell that diffuses to and affects adjacent cells
- Local hormones (affect only where produced)
Name the three differences between paracrines and hormones
- Target Cells
P-All cells of organ
H- Specialised cells - Transport
P-Extracellular fluid/diffusion
H-Bloodstream - Movement
P-Remain in organ
H-All around body
Explain how Protein and Amine hormones work
- Bind to membrane as water soluble // can’t pass through
1. Protein attach to receptor on membrane of target cell
2. Hormone receptor complex
3. Secondary Messenger diffuses through cell
Explain how Steroid hormones work
- Insoluble // diffuse through phospholipid bilayer + bind to organelles
What is enzyme amplification and what does it allow
- Small stimulus> large effect
> EA: A series of chemical reactions in which the product of one step is an enzyme that produces an even greater number of product molecules at the next step
What is hormone clearance and what are the two ways they are cleared
- Desired effect > turned off
1. Broken down in target cell, or liver or kidney
2. Excreted in bile or urine
Define negative feedback
>
Negative feedback systems: a situation in which feedback brings about the opposite to, or reduces the effect of, the original stimulus
What is releasing factors and inhibiting factors
o Releasing factors- stimulate release of hormone
o Inhibiting factors- slow down secretion of hormone
How is the pituitary joined to the hypothalamus
infundibulum
What are the two parts of the pituitary glands and what are their other names
Anterior (adenohyphsis)
Posterior (neurohypophsis)
How are the anterior and posterior lobes connected to the hypothalamus each
Anterior= blood vessels (not nerves)
Posterior= nerves
What are secretions of the anterior controlled by
releasing inhibiting factors
What are the 6 hormones the anterior lobe releases
- FSH
- Luteinising hormone
- Growth hormone
- Thyroid stimulating hormone
- Adrenocorticotropic hormone
- prolactin
Where is FSH released, its target organ and its effects
Anterior,
ovaries
testes
development of gamates
Where is LH released, its target organ and its effects
Anterior
Ovaries and testes
O- ovulation
T- secretion of testosterone
Where is growth hormone released, its target organ and its effects
Anterior
all cells
growth and protein synthesis
Where is thyroid stimulating hormone released, its target organ and its effects
Anterior
thyroid gland
secretion of hormones of thyroid
Where is adrenocorticotropic released, its target organ and its effects
Anterior
adrenal cortex
secretions of hormones from AC
Where is prolactin released, its target organ and its effects
Anterior
Mammary glands
milk production
Why is posterior not a true gland
no hormones created only released
How does the posterior work
o Hormones made in nerve cells in hypo > move down extensions through infundibulum to posterior > stored until release triggered by nerve impulses in hypo
What are the two hormones released by the posterior
Antidiuretic hormone
Oxytocin
Where is antidiuretic hormone released, its target organ and its effects
posterior
kidneys
reabsorption of water
Where is oxytocin released, its target organ and its effects
posterior
mammary glands (release milk) , uterus (contraction)
What does the pineal gland secrete and what does the hormone do
- Secretes melatonin
o Involved in regulation of sleep patterns
o Stimulated by darkness, inhibited by light
What is the main secretion of the thydroid gland, whats its target cell, and its main effects
Thyroxine
most cells
increase metabolic rate > heat production and oxygen consumption
What does the parathyroid gland release, its target organ and main effects
parathyroid gland (parathormone)
bones and kidney
increase Ca level in blood
What are the two disorders of the parathyroid
o Hyperparathyroidism: increase PTH secretion> bones soften and too much calcium= kidney stones
o Hypoparathyroidism: too little PTH > little calcium affects NS
Where are thymosins released, its target organ and its effects
Thymus
Targets t lymphocytes
stimulates development and maturation
What are the two parts of the adrenal gland
medulla
cortex
Where is adrenaline and noradrenalin released, its target organ and its effects
medulla
most tissues
prepares for flight or fight, reinforces sympathetic NS
+ increase glucose levels
what does the adrenal cortex release
corticosteriods
aldosterone
cortisol
Where is aldosterone released, its target organ and its effects
a Cortex
kidney
reabsorption of Na and excretion of K
Where is cortisol released, its target organ and its effects
a cortex
most cells
promotes normal metabolism, helps body deal with stress, repair of damaged cells
What are the endocrine and exocrine roles of the pancreas
- Exocrine Role: Secretes digestive enzymes into small intestines through pancreatic ducts
- Endocrine Role: maintain glucose levels
Where is insulin released, its target organ and its effects
pancreas
most cells
uptake of glucose = lowers levels
Where is glucagon released, its target organ and its effects
pancreas
liver and fat storage
breakdown of glycogen and fat= increase levels of glucose
Where is androgens released, its target organ and its effects
testes
many tissues
male characteristics
Where is oestrogens released, its target organ and its effects
ovaries
many tissues
female characteristics
Where is progesterone released, its target organ and its effects
ovaries
uturus and mamammary glands
prepare for milk secretion, regulates menstrual cycle
What does the kidney secrete and what does it do
- (EPO)
stimulates production of RBC in bone
o Athletes take EPO as increase RBC count (which carry oxygen to muscles) to improve aerobic ability, delay fatigue
