Homeostasis & The Kidney Flashcards
What is homeostasis?
The maintenance of a state of dynamic equilibrium in the body despite
fluctuations in internal and external conditions.
Why is homeostasis important?
To ensure optimum conditions for enzymes and cellular processes in the body.
Define negative feedback.
Self-regulatory mechanisms return the internal environment to the optimum when there is a fluctuation.
Define positive feedback.
A fluctuation which triggers changes that result in an even greater deviation from the normal level.
What is the set point?
A desired value or range of values determined by a coordinator.
Describe receptors and effectors
- Receptors - specialised cells located in sense organs that detect a specific stimulus
Effectors - muscles or glands which enable a physical response to a stimulus
Describe the role of the coordinator.
Coordinates information from the
receptors and sends instructions to the effectors.
State the components of a negative feedback system.
- Set point
Receptors Coordinator - Effectors
What is the mammalian kidney?
One of a pair of organs in the abdomen that has a role in osmoregulation and nitrogenous excretion.
What is osmoregulation?
The regulation of the water potential of body fluids (e.g. blood, tissue fluid, lymph) by the kidney.
Why is osmoregulation important?
- Prevents cells bursting or shrinking when water enters or leaves by osmosis
Cellular reactions occur in aqueous solution ..
water levels affect concentrations and the rate of reactions in cells
Define excretion.
The process of removing metabolic
waste from an organism.
Describe how excess amino acids are
excreted.
Amino acids deaminated in the liver (removal of
amino group) to form ammonia
* Ammonia converted to urea (less toxic)
* Urea transported into the blood plasma and eliminated by the kidneys
What is the function of the renal artery?
Supplies blood to the kidneys.
What is the function of the renal vein?
Drains blood from the kidneys.
What is the function of the ureter?
Takes urine to the bladder from the
kidneys.
What is the function of the urethra?
Releases urine from the bladder, out of the body.
Describe the gross structure of a mammalian kidney.
Fibrous capsule - protects kidney
Cortex - outer region consists of Bowman’s capsules, convoluted tubules, blood vessels
Renal pyramids - cone-shaped subdivisions
Renal pelvis - funnel-shaped dilated section of
ureter
Medulla - inner region consists of collecting ducts, loops of Henle, blood vessels