Homeostasis Flashcards
What is Homeostasis?
A dynamic process where we adapt and adjust to maintain equilibrium in the bodies internal environment
What are the components of a feedback system? (5)
Set point, Sensor, Control centre, effector and the regulated variable
What are the 3 main feedback loops?
Positive feedback
Negative feedback
Feedforward loops
Describe Negative feedback
Acts to reduce a change in the body
Describe Positive feedback?
Acts to increase an effect in the body
Describe feedforward loops?
Physiological responses in anticipation of a change in a variable
What are the two types of glands in the body ?
Exocrine and Endocrine
What is the difference between Endo and Exocrine
Endocrine are ductless and secrete hormones into the blood whereas Exocrines secrete theirs through a duct
What are Hormones?
Hormones are chemical messengers carried by the blood to target cells to cause a response
What are the 4 main functions of Hormones?
1) Hormones help regulate chemicals, metabolism, immune system, cardiac muscle fibres and glandular secretion
2) Control growth and development
3) Regulate operation of reproductive system
4) Help establish circadian rhythm
What are the main differences with Endocrine system and the Nervous sytem?
Endocrine act relatively slower
however have longer lasting effects
What are the 3 main structures of Hormones?
Amines, Peptides/Proteins and Steroids
How do Peptide hormones travel, compared to Amine and Steroids?
Peptides are water soluble therefore circulate dissolved in plasma whereas the others circulate bound to proteins
What is mainly responsible for removing hormones ?
The Liver and Kidney
How do hormones get to the target cells?
Lipid soluble hormones (such as steroids and thyroids) attach to receptors inside cells whereas water soluble hormones (such as proteins) attach to receptors on the membrane
What affects responsiveness of target cells to Hormones?
1) Hormones blood conc
2) Amount of target cells and/or receptors
3) Effects of other hormones
Name and describe 3 Hormonal interactions
Permissive - One hormones Increases activity of another
Synergistic - Two hormones acting together as it is greater than one alone
Antagonistic - A hormone hindering another
What are 3 inputs that control Hormone secretion?
1) Plasma Concentration of an ion or nutrients that is regulated by the hormone
2) Neural input to the endocrine cells
3) Other hormones
What is the hormone process?
Hormones are synthesized in the hypothalamus
axons pass down the infundibulum
terminate in the posterior pituitary and release hormones
What 6 things does the anterior pituiarty gland secrete?
Growth Hormone (GH)
Thyroid stimulation hormone (TSH)
Adrenocorticotropic (ACTH)
Prolactin
Follicle Stimulating hormone (FSH)
Luteinizing hormone (LH)
What is anterior pituitary gland secretion controlled by and what is the typical sequence of it?
It is controlled by Hypophysiotropic hormones from the hypothalamus via portal vessels
Hypophysiotropic hormones controls the secretion of APG hormone which then controls secretion of a 3rd hormone from an endocrine gland
Where is the thyroid gland located?
Sits within the neck in front of the trachea
Thyroid hormones function?
protein synthesis in follicular epithelial cells
increases DNA replication and cell division
produces thyroxine (called T4) and triiodothyronine (T3-major thyroid hormone)
What is cortisol mediated by?
Hypothalamus-anterior pituiarty gland system
