Circulatory systems Flashcards
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What distance can diffusion play an important role in substance exchange?
<100um
What is the rate of diffusion?
Fick’s law: Rate of diffusion α surface area x concentration difference
(divided by) thickness of membrane
What is an open circulatory system?
Where circulatory fluid does not return to the heart. In anthropods the hemolymph, which bathes body cells and organs, in sinuses exits through pores throughout the body
Capillary beds are the sites of exchange for which networks?
blood and interstitial
What blood vessel converges into veins?
Venules
Bony fish have how many ventricles?
1
Fish have a low metabolic rate because they are..
ectothermic
What 2 circuits do amphibians possess?
The systemic circuit and the pulmocutaneous circuit
Amphibians have a ___ dividing the atrium
ridge (not septum)
Mammals and birds require more O2 because they are _____
endotherms
What is the diastole phase of the cardiac cycle?
the relaxation, filling phase
What is the systole phase of the cardiac cycle?
The contraction or pumping phase
Where is the pulmonary valve?
In the pulmonary artery leading away from the right ventricle
What is the name of the valve leaving the right atrium into the right ventricle?
Tricuspid valve
What is the name of the valve in the aorta
Aortic valve
What is the name of the valve leaving the left atrium into the left ventricle
Mitral valve
Which valves are atrioventricular valves?
Tricuspid and mitral. They attach to tendinous cords
Which valves are semilunar valves?
Aortic and pulmonary. Operates due pressure preventing backflow
What does autorhythmic mean? (in regards to muscle cells)
contract repeatedly without any signal from the nervous system
Where is the SA node located?
in the right atrium
STEP ONE OF HEART CONDUCTION SYSTEM
Both atria contract in unison
STEP TWO OF HEART CONDUCTION SYSTEM
The AV node relays electrical impulses.. delaying for 0.1 secs to allow for atria to drain
STEP THREE OF HEART CONDUCTION SYSTEM
Bundle branches pass signals to heart apex.
STEP FOUR OF HEART CONDUCTION SYSTEM
signals spread throughout ventricles contracting upwards
What effect does epinephrine have on the SA node?
Speeds up SA node
Which system controls heart rate?
The autonomic nervous system, sympathetic and parasympathetic
Which T levels of spinal cord does the sympathetic nerves that release norepinephrine which acts on entire heart do they originate from?
T1-T4, increases heart rate and force of contraction
Where do the parasympathetic nerves originate from that mostly act on SA node?
Vagus nerves, release acetylcholine which decreases heart rate and force of contraction.
What is stroke volume?
Amount of blood pumped in a single contraction
What blood vessel type contains valves?
Veins
What are two qualities of arteries?
To act as a pressure reservoir for forcing blood into small diameter capillaries
To dampen oscillations in pressure and flow generated in the heart
Which blood vessel type acts as a storage reservoir?
Veins
How is blood returned to the heart from veins considering how low the pressure is?
One-way valves
Skeletal muscle contraction
What is Deep Vein Thrombosis (DVT)?
Pooling of blood in deep veins leading to a clot formation
How do you calculate pulse pressure?
Systole - diastole
Why does velocity increase again after entering capillaries unlike pressure?
Pooling back into bigger blood vessels
How do things move in and out of capillaries?
Actively by bulk flow through intercellular spaces between endothelial cells
What are the tight junctions in the capillaries?
lose intercellular spaces forming the blood-brain barrier
Require a greater number of mitochondria
How is fluid exchanged in the capillaries?
thin capillary endothelial cell wall
Blood pressure tends to drive fluid out of capillaries
Blood proteins, creating osmotic pressure, tends to pull fluid back into capillaries
On average there is a net loss of fluid from capillaries
What is the net pressure of fluid exchange in the arterial end?
(32mmHg - 22mmHg) 10mmHg .. fluid flows out
What is the net pressure of fluid exchange in the venous end? (think blood pressure dropping)
15 - 22 = -7mmHg , fluid flows in
What is the net fluid exchange overall?
(10 - 7) 3 mmHg
What happens to the overall net fluid?
The lymphatic system returns fluid that leaks out from capillary beds.. fluid lost is lymph. Drains into veins in the neck. Valves in lymph vessels prevent backflow
What is oedema?
Swelling caused by disruptions in the flow of lymph
What is the pleural membrane, space/cavity and fluid?
Parietal and visceral layers/pleura
Potential space between these layers containing fluid
Fluid prevents friction, causes layers of pleural membrane to adhere to one another (surface tension)
What kind of epithelium make up the alveoli
Simple squamous
What makes up the respiratory membrane?
Fluid with surfactant lining the alveolus reduces surface tension & allows alveolar expansion when breathing in.
Alveolar epithelium
Interstitial space
Capillary endothelium
-Diffusion distance is 0.2-0.6μm (short)
Is the pressure negative or positive when breathing in?
negative
How is breathing controlled?
Regulated by blood pH (~7.4). If pH falls (due to rising CO2 levels) sensors in the aorta and carotid arteries at the same time as the medulla detects pH in cerebrospinal fluid. The medulla signals for increased breathing.
What is haemoglobin?
A protein containing four subunits each consisting of a polypeptide chain & a haem group
Each haem group contains an iron atom to which an oxygen molecule can bind
What are the main values of partial pressure needed for oxygen transport?
Air is 160 mmHg
Lungs are 100mmHg
Tissue: 40mmHg at rest and <20 mmHg during exercise
Venous blood is 40 mmHg
Arterial blood is 95mmHg
What is the haemoglobin dissociation curve displaying?
There is co-operativity between the haem subunits
Thus when one subunit unloads O2 the others then more readily unload
This is because changes in their shape decrease their affinity
How is CO2 transported in the blood
90% as: CO2 + H2O = H2CO3 (carbonic acid)
catalysed by carbonic anhydrase within red blood cells
H2CO3 = H+ + HCO3- (bicarbonate)
