4. Kondisi internal yang perlu dikontrol misalnya :
Temperatur
air dlm tubuh
ion dlm tubuh
pH darah
5. Mekanisme Homeostatik melibatkan:
•Reseptor - menerima informasi
•Pusat kontrol - memerintahkan apa yg harus
dilakukan
•Effektor – merespon utk merubah
lingkungan internal
1-10
6. Fedback negatif
Terjadi jika ada
perubahan yg
menyebabkan
sistem merespon
utk mengurangi
StatusNormal
Perubahan
(peningkatan/penurunan)
Terdeteksi
oleh reseptor
Respon oleh
Kelenjar/otot
(organ efektor)
Pengurangan
stimulus
Feedback
negatif
7. Thermoregulasi
Kontrol tubuh terhadap temperatur
maximize metabolic efficiency
reduce oxygen use
protect enzyme function
reduce calorie expenditure
8. Temperatur tubuh dimonitor dan dikontrol
oleh pusat termoregulator di hipotalamus
Mempunyai reseptor yg sensitif thd suhu
darah yg mengalir ke otak
Reseptor temperatur di kulit mengirim impuls
ke pusat -----beri informasi suhu kulit
9. Apa yg terjadi jika tubuh
terlalu panas?
Otot kulit akan relaksasi,
rambut flat
Glandula sudorifera
sekresi keringat di
permukaan kulit utk
meningkatkan
pembuangan panas scr
evaporasi
Vasodilatasi pembuluh
darah kulit, panas banyak
dibawa darah ke kulit,
dibuang ke udara
10. Apa yg terjadi jika
tubuh terlalu
dingin?
Otot kulit berkontraksi,
rambut tegak
Glandula sudorifera
berhenti mensekresi
Vasokontriksi pembuluh
darah kulit
Kontraksi dan relaksasi
otot secara cepat,
menghasilkan energi
panas (menggigil)
18. Normal status
Air< < di darah
Terdeteksi oleh
hipotalamus
ADH >> dilepaskan
Oleh glandula pituitaria
Ginjal mengabsorbsi
Banyak air
Produksi Urin <<
Misalnya krn apa???
19. Normal status
Air >> di darah
Terdeteksi oleh
hipotalamus
ADH << dilepaskan
Oleh glandula pituitaria
Ginjal mengabsorbsi
Sedikit air
Produksi Urin >>
Karena apa???
20. Blood pH = 7.4 (7.35-7.45)
pH darah diatur oleh
1. Kidneys
2. Lungs
3. Buffers in blood
22. Pengaturan pH oleh ginjal
Jika pH terlalu rendah
Ekskresi ion hidrogen, mempertahankan
bikarbonat
Jika pH terlalu tinggi
Mempetahankan hidrogen, ekskresi bikarbonat
23. Pengaturan pH oleh paru
Jika pH terlalu rendah
Bernafas lebih cepat untuk mengeluarkan
CO2 (CO2 akan membentuk asam karbonat
dlm darah)
Jika pH terlalu tinggi
Bernafas lebih lambat utk mempertahankan
CO2
25. More Carbon Dioxide = More Acid
= Lower pH
Breathing slower will retain CO2 , pH will
decrease (more acid)
Breathing faster will eliminate more CO2 pH
will
increase (less acid)
26. Blood pH Drops to 7.3
How does the body compensate?
Breath faster to get rid
of carbon dioxide
eliminates acid
27. Blood pH Increases to 7.45
How does the body compensate?
Breath slower to retain
more carbon dioxide
retains more acid
Editor's Notes
You recall that osmosis is the movement of water across a membrane to the side of the membrane with more solutes. Which way will water move in this example? The concentration of solutes is greater inside the cell in this example. *Water will therefore move into the cell.
In this example a cell with the equivalent of 0.9% NaCl is in a 3% NaCl solution. Which way will water move? *Water will move to the outside of the cell. Since the solution outside the cell has more solutes we say it is a hypertonic solution.
Which way will water move in this example? *Water will move into the cell because there are more solutes in the cell. *The solution outside of the cell is hypotonic.
Antidiuretic hormone is produced by the hypothalamus of the brain. *ADH works on collecting ducts of kidney nephrons. ADH will cause the pores of the collecting duct to dilate and thus allow water to move faster. *Water will leave the collecting duct because the interstitial fluid around the collecting duct is hypertonic. ADH prevents the body from losing too much water.
The pH of the blood is normally about 7.4. It can fluctuate between 7.35 and 7.45 and still be in homeostasis. *To maintain homeostasis the body has several mechanisms to regulate pH. *The kidneys play a major role in the regulation of pH. *Our lungs also help to maintain normal pH. *Also, buffers in the blood help keep the pH in the normal range.
This diagram illustrates how the kidneys regulate blood pH. The nephron of the kidney pulls hydrogen ions out of the blood and excretes them in the urine. Also, the kidneys will pump the base, bicarbonate into the blood. Bicarbonate will neutralize acids.
The kidneys can adjust the blood pH whether the pH is too low or too high. *If the pH is too low the kidneys can excrete excess hydrogens and retain bicarbonate. *If the pH is too high the kidneys will retain hydrogen ions and excrete bicarbonate.
The lungs regulate pH by regulating the amount of carbon dioxide in the blood. *If the pH is too low we can breath faster to get rid of excess carbon dioxide. You recall that carbon dioxide forms carbonic acid in the blood. By eliminating carbon dioxide we eliminate carbonic acid. *We will breath slower to retain carbon dioxide if the pH is too high. The extra carbon dioxide forms carbonic acid to lower the pH.
Carbon dioxide will form carbonic acid as illustrated on this slide. *Carbonic acid will release the hydrogen ion. It is hydrogen ions that determine the pH.
More carbon dioxide means more acid and a lower pH *By breathing slower the body will retain carbon dioxide and the pH will decrease or become more acidic. *Breathing faster will eliminate more carbon dioxide and the pH will increase or become less acidic.
If the blood pH drops to 7.3 how does the body compensate? *One thing it will do is breath faster to get rid of carbon dioxide. Eliminating carbon dioxide will eliminate acid and raise the pH.
If the pH increases to 7.45 how does the body compensate? *It will breath slower to retain more carbon dioxide. This will increase the acid level in the blood to lower the pH.