osmoregulation

  • the human body
    • the human body is made up of liquid components
    • the actual amounts may vary with age and sex
    • infants are approximately 75% water
    • adult females are about 55% water
    • water balance is about matching intake with output
  • regulation of body fluids
    • sources of fluid for the body
    • daily intake : average 2500cm3
    • drinking fluids
    • 1600cm3 drinking fluids
    • food
    • 700cm3 in food
    • metabolic water - water that is produced because of the chemical reactions taken place in the body
  • losing body fluids
    • urine
    • 1500cm3
    • breathing
    • 300cm3
    • through the skin
    • 500cm3
    • in faeces
    • 200 cm3
  • body fluids
    • water
    • electrolytes
    • non electrolytes
  • electrolytes
    • ionic compounds that form anions and cations in solution
    • mainly inorganic ions but also few organic ions
    • many are essential for bodily functions
    • carry electric current so are responsible for nerve impulses transmission
    • control acid/base balance in the body
  • non electrolytes
    • covalent molecules
    • mainly organic compounds
    • glucose
    • urea
    • creatine
  • osmosis and osmoregulation
    • the overall concentration of dissolved electrolytes and non electrolytes in intracellular fluid and extracellular fluid is important
    • the concentrations must be balanced to prevent osmosis taking place
    • uncontrolled osmosis can damage cells
    • osmosis is the movement of water down a concentration gradient of water
    • requires the presence of a partially permeable membrane
    • occurs when solutions of different strengths are separated by a membrane
    • maintenance of the current levels of electrolysis is important for proper function of the body
  • water potential
    • this is in effect a measure of the amount of dissolved material or solute present in a solution
    • the units used for water potential are kPa (also used for pressure in chemistry)
    • the water potential of pure water is 0 kPa
    • adding a solute to pure water will lower the water potential
    • the water potential of all solutions is a negative number
  • solutions and cells
    • hypertonic solution
    • more solute or less water than inside the cell
    • hypotonic solution
    • less solute and more water than inside the cell
    • isotonic solution
    • the amount of solute and water are the same as inside the cell

Regulation of sodium ions in the body

  • controlled by a hormone called aldosterone
  • hormone secreted by the [art of the adrenal gland called the cortex
  • aldosterone acts on the kidney tubules
  • presence of hormone increases the uptake of sodium from the nephron back into the blood
  • aldosterone action
    • aldosterone also has an effect on the levels of potassium and chlorine
    • increased reabsorption of sodium leads to increased reabsorption of chlorine
    • raising the levels in the blood
    • at the same time aldosterone increases the rate at which potassium is excreted by the kidneys
  • mechanism of aldosterone release
    • this is a complex pathway
    • decreases in blood pressure resulting from dehydration or sodium deficiency causes certain kidney cells to produce an enzyme called renin
    • renin acts on a plasma protein called angiotensinogen and converts it into amniote 1
    • angiotensin 1 is converted into angiotensin 2 by angiotensin converting enzyme (ACE)
    • angiotensin 2 is a hormone that stimulates a rise in blood pressure by vasoconstriction in arterioles and adrenal cortex to produce aldosterone
  • male and female organs

 

  • functions : male
    • testis - responsible for making sperm - human testosterone is secreted
    • epididymis - to bring sperm to maturity - they carry and store sperm to be matured
    • sperm duct - to allow the transit of sperm from inside to the outside of the body -
    • seminal vesicles - important for fertility
    • prostate - produces fluids that nourishes and transports sperm
    • urethra - allow urine to pass outside the body - allows sperm to pass out (secretes)
    • penis - for urination and sexual intercourse
    • scrotum - regulates the temperature
  • function : female
    • ovary - produce egg cells + hormones progesterone and oestrogen
    • follicle - oocyte maturation and release and steroidogenesis required for regulating its own growth and providing the proper environment in reproductive organs for the transport of gametes and nidation
    • fallopian tube - egg from the ovary to the uterus
    • uterus - also known as the womb
    • myometrium - induce uterine contractions
    • endometrium - preparation for implantation, maintenance of pregnancy if implantation occurs, and menstruation in the absence of pregnancy
    • cervix - passage into and out of
    • vagina - birth canal