Hormonal Co-ordination in Animals - The Endocrine System + Kidneys + Kidney Treatments+ Flashcards
What is the endocrine system and what does it do?
- made of glands
- secretes hormones into bloodstream
- blood carries hormone to the target organ
- effects are slower, longer lasting compared to nervous system
What are hormones and what is their function?
- hormones are chemical molecules released directly into the blood
- are carried in the blood to other parts of the body, only effect particular cells in particular organs - target organs
- hormones control things in organs and cells that need constant adjustment
where are hormones produced?
produced and secreted by various glands, called endocrine glands
hormones have short/long lasting effects?
long
name 6 examples of glands within the human body:
- the pituitary gland
- ovaries - females only
- testes - male only
- thyroid
- adrenal gland
- pancreas
what is the function of the pituitary gland?
- produces many hormones that regulate body conditions
- hormones act on other glands–> directing them to release hormones that bring about change
what is the function of the testes?
- produces testosterone –> controls puberty + sperm production in males
what is the function of the ovaries?
- produces **oestrogen –> involved in the menstrual cycle
what is the function of the thyroid?
- produces thyroxine –> regulates things like :
- rate of metabolism
- heart rate
- body temperature
what is the function of the adrenal gland?
- produced adrenaline
- used to prepare the body for ‘flight or fight’ response
what is the function of the pancreas?
- produces insulin –> regulates blood glucose level
what are the differences between hormones and nerves?
NERVES:
- very fast reaction
- act for a very short time
- act on a very precise area
HORMONES:
- slower action
- acts for a long time
- acts in a more general way
what is blood glucose controlled by?
- homeostasis
- insulin and glycagon are the 2 hormones involved
What is the pancreas role in maintaining the blood glucose levels
- pancreas continuously monitors blood glucose levels
- Produces 2 hormones involved into regulation:
- insulin
- glucagon
- secreted into the blood stream
- travel in blood to their target organs (the liver) where response occurs
When blood glucose levels are too high what hormone is secreted, the process and what are the effects?
- pancreas secretes insulin
- Effect on Liver : insulin makes
liver converts glucose to glycogen, and stored in liver and skeletal muscles - Effect on glucose levels: goes down as glucose is removed from blood
When blood glucose levels are too low what hormone is secreted and what are the effects
- pancreas secretes glucagon
- glucagon makes liver converts glycogen —> glucose
- glucose levels increase and released into blood from the liver cells
The blood glucose level is kept constant by a n………….. f……………… m…………….
Negative feedback mechanism
What is negative feedback ?
- when the internal factor rises above the normal level, the body responds by lowering the factor
- vice versa when the internal factor is below the normal level
What is the kidney’s main function
To maintain the water balance of the body
- excess water, excess ions and urea are removed via the kidneys in the urine
The kidney is a specialised organ in which body system
Urinary system
How is water taken into the body?
ingesting food and drinks
What are the 2 ways water can leave the body?
- via the lungs during Exhalation
- from the skin as Sweat
What substances are lost in sweat
- water
- ions
- urea
What happens during the filtration process?
- kidneys make urine by taking waste products out of your blood.
- substances are filtered out of the blood as it passes through the kidneys
What is selective re-absorption?
- useful substances like glucose, some ions and the right amount of water are absorbed back into the blood after the kidney filtrates unwanted substances out
How is Urea excreted from the body:
- ** Excess proteins and amino acids** cant be stored in the body — a process called deamination in the liver converts some amino acid into fats and carbohydrates, which can be stored
- ammonia is produced as a waste product
- ammonia is toxic so its converted to urea in the liver. Then transported to the kidneys, where its filtered out of blood and excreted from body in urine
What are the effects of the ion concentration changing?
- Ions such as sodium enter the body through the ingestion of food and are absorbed into the blood
- If ion concentration too high —> cells loose water and become crenated / if concentration too low —> cells may rupture
How is the right amount of ions maintained within the body?
- some ions are lost in sweat —> but this amount is not regulated
1. right amount is maintained by the kidneys - right amount of ions are reabsorbed back into blood after filtration
- kidneys filter excess ions out of blood and excreted from body into urine
Why is water regulation essential?
To prevent cells rupturing or crenating
How does the body constantly balance the intake and output of water?
Uncontrolled Loss
- lost water from skin or sweat
- lost from lungs when breathing out
Controlled lost
- the amount we consume
- kidneys remove excess water from blood
- excretes in urine
What is glucose and why is it essential?
A small soluble simple sugar
Essential for all cells for respiration
How do the kidneys control the concentration of glucose?
Kidneys selectively reabsorbs glucose to return it to the plasma
What are the kidneys 2 functions?
- filter waste materials out of blood
- Control the water levels o the blood
What are nephrons?
Thousand of tiny tubes in the kidney. They extend from the renal Cortes into the renal medulla
What are the 2 functions of nephrons?
- filtering the blood
- reabsorbing any useful substances
During filtration name 7 substances that are filtered out of the blood
- glucose
- ions - Na, K
- urea
- water
- oxygen
- amino acids
- carbon dioxode
What are the 3 substances that cant be filtered out of the blood and why?
- proteins
- red/white blood cells
- platelets
too big
During selective reabsorption what are the substances that are reabsorbed back into the bloodstream and what is the amount?
- all glucose
- all glucose
- some water
- some ions
What substance is not reabsorbed into the blood steam by selective absorption and why?
No urea is absorbed
slightly toxic + not useful
What substance does healthy urine contain
- urea
- excess water
- excess ions
What does healthy urine no contain**
- red/white blood cells
- glucose
- amino acid/ proteins
What process happens to excess amino acids in the liver?
deamination
Amino acids broken down into urea
What detects the water content of the blood?
Receptors in the hypothalamus (in the brain)
Which hormone controls the water level in the body and what does it act on?
ADH
Acts on the kidney tubules
What happens if the water content of the plasma is too low
- ADH produced + secreted by the pituitary gland
- this increases permeability of the kidney tubules to water
- causes more water reabsorbed back into water plasma by kidney tubules
- less water lost in urine - more concentrated
- blood water levels return back to normal
State the process when the water content of the plasma is too high?
- pituitary gland releases less/no ADH
- decreases permeability of kidney tubules to water
- less water reabsorbed by kidneys into blood
- more water lost in urine - more diluted
what does ADH stand for
Anti - Diuretic Hormone
what does kidney failure result in?
- waste substances build up in the blood and you lose ability to control the levels of ions and water
- can result in death as toxin, such as urea build up in the blood
kidney damage can occur as a result of:
- kidney infection
- genetic disease
- road traffic accident
why does dialysis have to done regulary?
to keep concentrations of dissolved substances in the blood at normal levels, and to remove waste substances
what is the dialysis machine consist of and why?
partially permeable membrane that is surrounded by dialysis fluid
- its is permeable to things like ions and waste substances, but not big molecules like proteins
- to mimic membranes in kidney
Dialysis fluid has the same concentration of what as in healthy blood and why?
same concentration of **dissolved ions and glucose
- prevents the net movement of glucose across the membrane as no concentration gradient exists
- means that useful dissolved ions and glucose won’t be lost from blood during dialysis
- patient needs to retain glucose for respiration
does dialysis fluid contain urea and why?
No
- ** large concentration gradient** compared to blood
- means ureadiffuses across partially permeable membrane from blood to dialysis fluid
- urea is toxic - essential to remove from patient blood
dialysis fluid contains what ion concentration level compared to the ideal blood plasma concentration and why?
- ion concentration similar to the ideal blood
- patients blood too low in ions : diffuse from the dialysis fluid –> blood
- patients blood too high in ions : diffuse from blood –> dialysis fluid
describe the process of how dialysis works
- blood leaves arm through an artery
- blood passes through a pump that maintains blood pressure to ensure blood continues to flow
- anticoagulants added to prevent clotting
- thinned blood enters dialysis machine
- blood passes over dialysis membrane
-
dialysis fluid flows in the opposite direction to blood (counter current system)
- allowing exchange to occur between the two where a concentration gradient exists -
waste materials removed as they move down the concentration gradient:
- all urea removed - diffusion
- excess ions - diffusion
- excess water - osmosis - glucose not removed - dialysis fluid and blood have same concentration so no diffusion gradient
- filtered blood continues to flow through system to a bubble trap (gets rid of bubbles)
- filtered blood returns to patient
what are the advantages of a dialysis machine?
- can but patient valuable time if kidney donor not found
- widely available to all kidney patients (no shortage)
disadvantages of dialysis
- requires sessions of 3-4 hours for 3 times a week - very time consuming
- may cause blood clot or infection
- very expensive
what is the only cure for kidney failure?
kidney transplant
who can donate a kidney
- close relatives - higher chance of tissue match
- strangers with tissue match
why may the the donor kidney be rejected?
antigens on the surface of the donor kidney cells are recognised as foreign and causes immune system to attack donor kidney
what happens when a organ is rejected
antibodies of the recipient attack the antigens of donor kidney causing kidney cell and tissue death
how can the risk of injection be reduced?
- take immunosuppressants for life** - reduce risk of rejection but also reduce recipients ability to cope with all infectious diseases
- tissue match the organ that is donated - closer the tissue match less chance of rejection
what situation results in no risk of rejection?
identical twin - have the same antigens on their cell membranes
advantages of kidney transplant
- normal life with no regular trips to the hospital
- long term cost is low
- good success rate - 80% if close tissue match
disadvantages of kidney transplant
- needs to take immunosuppressants for life
- Kidney only lasts 8-9 years on average
- shortage of suitable donors - long wating list
- tissue matching is essential
- donated organ must be transplanted within 12 hours
