circulatory system Flashcards
why do multi-cellular organisms need a circulatory system?
- small SA:V
- high metabolic rate
- high respiration rate
double circulatory system
the blood passes through heart twice before one circuit is completed (different in fish)
open circulatory system
blood flows freely through body cavity
transported back to heart through valves
blood in this case not used for oxygen supply
arteries
- thick and muscular walls
- elastic tissue to stretch and recoil when heart beats
- endothelium folded –> arteries can expand
arterioles
= smaller arteries
- less elastic tissue
- layer of smooth muscle
capillaries
- walls one cell thick –> easier diffusion
venules
small veins
space where blood flows through
lumen
veins
- wider lumen
- little muscular/elastic tissue
- valves to prevent backward flow
capillary bed
the network of capillaries in an area of tissue
tissue fluid
surrounds cells in tissue
how is the fluid pushed in and moved out of space between tissues?
pressure filtration
out: also lymphatic system
why are no red blood cells in the tissue fluid/ lymph
too big to get through capillary walls
when do white blood cells enter tissue fluid?
when there is an infection
when are platelets in the tissue fluid
when capillaries are damaged
systemic circuit
body circuit
pulmonary circuit
circuit of blood that flows through the lungs
What makes red blood cells so perfect for oxygen transport?
- high SA:V
- no nucleus
- small & flexible –> move through capillaries easily
white blood cells function
phagocytosis
lymphocytes: production of antibodies
platelets
cell fragments
make blood clot
plama transports:
heat, hormones, blood cells, CO2, digested food, urea
which chamber of the heart receives blood from the lungs?
the left side
myogenic
cardiac muscle can contract and relax without receiving signals from the nerves
why do the ventricles contract after the atria?
the AVN has a slight delay before it reacts to the signal of the SAN
conduction system of the heart
SAN
AVN
bundle of His
Purkyne tissue
Why does the electric signal not spread through the whole muscle straight away?
non-conduction collagen tissue
How can an electrocardiograph monitor heart activity?
the heart muscle depolarizes when it contracts and repolarizes when it relaxes
Where is the greatest blood pressure in the body?
Aorta –> blood just ejected from heart
How high is the blood pressure in capillaries?
largely dissipated (zerstreut) (large number of capillaries)
What kind of vessels have capillaries on both sides?
vessels connecting two organs (like the hepatic vein)
