endocrine system Flashcards
what is a hormone
a chemical messenger released by an endocrine gland. they travel in the bloodstream to a specific target organ or tissue where they have an effect.
what is the purpose of the endocrine system
chemical communication in the body
what do endocrine glands regulate?
- metabolism
- growth/development
- reproduction/sexual function
- sleep/mood
gland
An organ or group of specialised cells in the body that produces and secretes a specific substance, such as a hormone
why are only target cells affected by hormones
because they have receptors in their cell membranes
Why must levels of glucose in the blood be controlled?
To provide cells with glucose for respiration/ To stop osmosis of water out of body (somatic) cells into the blood (see diabetes symptoms and issues)
What two hormones control the level of glucose in the blood? Explain the effect of each on blood glucose levels
Insulin (stimulates target cells in the liver to absorb glucose and make Glycogen).
Glucagon (stimulates receptors in target cells in the liver to hydrolyse Glycogen to glucose and release it into the blood stream)
What glandular organ secretes glucagon and insulin?
the pancreas
What endocrine tissue within this glandular organ contains the alpha and beta cells that secrete these hormones?
islets of langerhans
Which cell (alpha or beta) secretes insulin? Which secretes glucagon?
Alpha cells produce Glucagon; Beta cells produce insulin
What disease does someone have if they are unable to produce insulin or their cells are not sensitive to insulin?
diabetes
Why are glucagon and insulin known as antagonistic hormones?
they work in opposite ways
What kind of biological molecule is glycogen?
Polysaccharide (carbohydrate) that serves as a form of energy storage in animals
If the glycosidic bonds in glycogen are broken, what are the monomers that are released?
(Alpha) glucose – can be used in respiration to make energy (ATP)
Insulin regulates levels of what molecule in the blood?
glucose
What disease would be caused if insulin cannot be produced/cells are not sensitive to it?
diabetes
Why do levels of glucose in the blood need to be controlled?
- To supply cells with a constant supply of glucose to allow them to carry out respiration
- To stop high levels building up in the body (seen in Diabetes) which can damage the kidneys and other organs.
the pancreas
s a glandular organ in the upper abdomen that secretes the hormones insulin and glucagon to control blood glucose levels
what are the 2 main types of endocrine cells that make up islets of langerhans
alpha and beta cells
what hormone do alpha cells produce
islet of langerhans
glucagon- which raises blood glucose levels
what hormone do beta cells produce
islet of langerhans
insulin- which lowers blood glucose levels
Glycogenolysis
the metabolic breakdown of glycogen to glucose
glycogenesis
the formation of glycogen from glucose
what are antagonistic hormones
hormones that have the opposite effect in the body as seen.
what is the negative feedback system
a regulatory mechanism in which the levels of a hormone in the bloodstream are regulated by the hormone itself.
* When the level of a hormone in the bloodstream is too high, it triggers the release of a different hormone that decreases its production.
what 2 parts is the pituitary gland seperated into
- posterior lobe
- anterior lobe
what is the role of the pituitary gland
responsible for controlling and coordinating…
* growth and development
* organ function
* gland function
what is the function of the kidneys.
- they filter blood to remove wastes & excess water- these waste products are excreeted via urine
- also reabsorb & return needed substanes to the blood
what are the 3 main stages of kidney function?
- ultra-filtration (glomerular filtration)
- tobular reabsorbtion
- tobular secrertation
what 3 parts of the bowmans capsule does ultrafiltration involve?
- endothelium of blood capillary
- basement membrane
- endothelium of bowmans capsule
basement membrane properties (ultra-filtration)
- meshwork of collagen and glycoprotein fibres
- water & small molecules can pass through
- proteins are too large and their - charge repelled by charges on fibres
endothelium of blood capillary properties (ultrafiltration)
- very thin
- thousands of pores
- provides a barrier to cells but NOT plasma proteins
endothelium of bowmans capsule properties (ultrafiltration)
- made of cells modified for filtration- PODOCYTES
what are podocytes
- specially made cells modified for filtration
- have foot like extensions projecting from its surface
- extensions wrap around capillaries of glomerulus
- filtered fluid passes through filtration slits.
what does the proccess of ultrafiltration produce?
glomerular filtrate
summarise the process of ultrafiltration in the kidney
- Blood flows into the glomerulus from the afferent arteriole. This is wider than the efferent arteriole
- The difference in diameters puts the blood in the capillaries of the glomerulus under increased hydrostatic pressure
- The hydrostatic pressure in the glomerulus is higher than the Osmotic pressure in the Bowman’s capsule
- The pressure difference tends to push the fluid and soluble components of blood from the glomerulus into the Bowman’s capsule
what does damage to the filtration pocess cause?
- Elevated blood pressure will damage capillaries, widen podocyte slits and damage the basement membrane.
- This allows larger proteins and sometimes erythrocytes to enter the Bowman’s capsule.
causes of high BP
- obesety
- smoking - leading to CHD
- stressful job
- diabetes
summarise the process of tubular reabsorbtion
how are the cell lining in the proximal convulated tube specialised to achieve reabsorbtion?
- cell surface membrane in contact with tubule fluid is highly folded (increase surface area)
- membrane contains special co-transporter proteins
- membrane contains sodium potassium pumps (active transport)
- cell cytoplasm has many mitochondria (indicates an active process is involved)
