L35- The endocrine system Flashcards
what is the endocrine system?
works in co-oridnation with the NS to maintain homeostasis, works over a longer time frame than the NS.
What is a hormone? where is it secreted from?
a chemical substance that is used to carry information to one part of the body to another, via the blood. secreted from endocrine glands that are ductless, negative feedback.
How does a hormone work?
it activates a receptor at the target cell.
what are the two types of hormones?
- peptide e.g. insulin, adrenaline, oxytocin
- steroid e.g. sex hormones
can hormones pass through the cell membrane?
- steroid hormones are lipophilic so can pass CM
- peptide hormones are hydrophilic so can’t pass, receptors are at the cm
how do peptide hormones work during cell signalling?
peptide hormones bind to a receptor at the cell membrane causing a second messenger cascade. Binding leads to activation of an enzyme to covert ATP to cAMP(second messenger) leading to enzyme cascade
how do steroid hormones work during cell signalling?
SH diffuses through CM as it is lipid soluble, it then binds to receptor inside nucleus, =hormone-receptor complex which activates a gene and synthesis of specific mRNA molecule. mana moves to ribosomes and protein synthesis occurs.
what are the two types of tissue is the pancreas?
-exocrine, that produces and secretes digestive enzymes.
endocrine (islets of langerhans) produce and secrete insulin and glucagon directly into the blood.
what cells secrete what glucose homeostasis hormone?
a-cell secretes glucagon
b-cell secretes insulin
they detect levels of glucose in the blood
what is type 1 diabetes?
when the pancreas can not produce insulin
what is the role of the hypothalamus?
controls glandular secretions of the pituitary gland which in turn control secretion at other endocrine glands
What does the posterior pituitary release?
-Antidiuretic hormone (ADH) -Causes water to be reabsorbed into kidney
capillaries.
-Oxytocin– Causes uterine contraction during childbirth and
lactation.
