Lecture 3: Endocrine Flashcards
Define ‘hormones’.
Molecules produced by ductless (‘endocrine’) glands, which control cellular process in target tissues.
What type of cell releases hormones?
Endocrine cells.
How are hydrophilic hormones secreted?
Secreted via exocytosis since they are repulsed by the lipid membrane. They are transported to the bloodstream where they become dissolved messengers.
How are hydrophobic hormones secreted?
Secreted via diffusion. They are transported to the bloodstream where they bind to carrier proteins.
How do hydrophilic proteins bind to the receptor?
As they are repulsed by the lipid membrane, they bind to an external receptor on the cell surface. This induces a 2nd messenger system which activates genes.
How do hydrophobic proteins bind to the receptor?
They diffuse into the cell and bind to an internal receptor within the cytoplasm. The hormone-receptor complex can go on to directly activate genes.
What makes hormones different from other transmitters?
They are long-distance chemical messengers.
What factors may influence hormone levels?
- Internal feedback and mechanisms (homeostasis disrupted, developmental events)
- Environmental factors (social, climactic, seasonal)
- Other evolved effects (response to stimulation - touch or sound etc).
Describe steroid hormones.
- Fat soluble
- Hydrophobic
- Produced in mitochondria and sER.
Give examples of steroid hormones
- oestrogen (female sex)
- testosterone (male sex)
- glucocorticoids (stress)
- progesterone (reproductive behaviours especially in females, mood).
Describe peptide hormones.
- Made up of amino acids
- Hydrophilic
- Produced in heart, pancreas and fat.
Give examples of peptide hormones.
- Neuropeptides (brain hormones which do not pass into general circulation)
- Prolactin (stimulation of milk production).
Define ‘organisational effects’.
Long-lasting effects of hormones on development.
Define ‘activational effects’.
Short-acting, more reversible effects.
