3.2 Transport in animals Flashcards
What are three things which affect the need for a transport system?
size
sa:v
metabolic activity
Features of a good transport system?
medium to carry oxygen/nutrients- blood
pump- heart
exchange surfaces- capillaries
Give an example of a single circulatory system.
fish
heart-gills-body-heart
Advantage of double circulatory systems
After going through lungs, heart can increase pressure so it flows more quickly
What are the three layers of an artery?
tunica intima
tunica media
tunica adventitia
Why does the left ventricle need to be so thick?
needs pressure to overcome resistance of systemic circulation
What is the difference between systole and diastole?
systole= contract diastole= relax
Why is the heart myogenic?
it can initiate its own contraction
What are the two heart nodes?
Sino-atrial
Atrioventricular
Describe how a wave of excitation travels through the heart.
SAN node (pace maker) generates wave of excitation Wave of excitation spreads over both artia walls causing atria to contract (systole) At top of septum, AV node delays the wave allowing time for the atria to stop contracting
How does haemoglobin have a high affinity for oxygen?
4 polypeptide chains each have a haem group
Each binds to one oxygen molecule
So it binds to 4 O2 molecules
why does fetal haemoglobin need a higher affinity for oxygen?
(fetal haemoglobin) must be able to bind to oxygen,
in low(er) partial pressure /
in placenta
How is tissue fluid formed?
by pressure filtration through the capillary walls.
Down pressure gradient from capillaries
How are hydrogencarbonate ions produced in erythrocytes?
1 carbon dioxide, enters / diffuses into, erythrocytes ;
2 (carbon dioxide) combines / reacts, with water ;
3 correct ref to carbonic anhydrase;
4 forms carbonic acid ;
5 (carbonic acid) dissociates to form hydrogencarbonate
ions and, hydrogen ions / protons
How do substances that are dissolved in the blood plasma enter the tissue fluid from the capillaries?
diffusion ;
from high concentration to low concentration / down
concentration gradient;
(hydrostatic) pressure in capillary high(er than in tissue
fluid) ;
capillary (walls) leaky / described ;
fluid / plasma, forced out (of capillary)