Module 4 - Circulation and Gas Exchange Flashcards Preview

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Flashcards in Module 4 - Circulation and Gas Exchange Deck (63):

What kind of diffusion occur across the respiratory surface?

Passive diffusion.


What features must the respiratory surface have?

Respiratory surface must have large surface area and a thin membrane.


What does oxygen need to do before it can diffuse?

Oxygen needs to dissolve in fluid before it can diffuse.


What is partial pressure?

PP - the pressure exerted by a particular gas in a mixture of gases.


What is Henry's Law?

the solubility of gas in liquid is directly proportional to the partial pressure of that gas in equilibrium with the liquid


What type of exchange occurs in gills? Explain

Countercurrent exchange - this is where the water flows through gill filaments in the opposite direction of the blood flowing through the capillaries in the gill filaments. The pp of oxygen in water decreases as it flows through the gill filaments, and the pp of oxygen in blood being highest where the water first crosses.

Water: 150 120 90 60 30 (flowing left to right)
Blood: 140 110 80 50 20 (flowing right to left)


4 facts about tracheal systems

- exist in insects
- no link between gases and blood
- oxygen goes directly to cells
- moisture is easily lost as the size of the tracheole decreases


How many alveoli do humans have and what surface area does this create?

300 million alveoli gives 80 to 100 square metres


Pulmonary vs systematic circulation

- heart and lungs
- deoxygenated blood to lungs - oxygenation - oxygenated blood returns to the heart
- low pressure system
- removes CO2 from blood and adds O2

- heart and rest of the body
- oxygenated blood to the body - deoxygenation - deoxygenated blood returns to the heart
- high pressure system
- provides body cells with O2 and removes CO2


Positive vs negative pressure breathing

- inhaled air closed into nasal cavity, air rushes into lungs as pressure is lower there (push air into lungs).

- expansion of lungs reduces pressure, so air rushes into lungs (suck air in)
- exhalation by relaxation of diaphragm and rib muscles, decreases lung volume and air moves out of lungs


What is the change in volume in negative pressure breathing in humans?

Very small: 3-4 mmHg


Roles of preural sac

- forms a fluid filled double membrane surrounding the lung
- keeps lungs stretched and attached to ribs


What is the residual volume?

bottom 1200mL, always in the lungs, the volume of air remaining in the lungs after a maximal expiratory effort.


What is the expiratory reserve volume?

1100ml on top of residual volume, the max that can be exhaled after normal expiration


What is the funtioncal residual capacity?

residual + expiratory reserve = bottom 2300mL, the volume of air at the end of passive expiration.


What is the tidal volume?

500mL above functional residual capacity - the difference of volumes after normal inhalation and exhalation


What is the inspiratory reserve volume?

3000mL above tidal, the max that can be inhaled after normal inhalation


What is the insiratory capacity?

tidal plus inspiratory reserve - the max inhaltion after normal expiration


What is the vital capacity?

4600mL - that is total lung capacity minus the residual volume, the greatest volume of air that can be expelled from the lungs after taking the deepest possible breath.


What is the total lung capacity?



What are the responses to an increase in CO2 concentration in the blood?

- decreased pH
- increased rate and depth of ventilation


Partial pressures in mmHg of O2 and CO2 in 6 phases of respiration

Inhaled air - 160 O2, 0.2 CO2
Alveolar spaces - 104 O2, 40 CO2
Pulmonary veins and systemic arteries - 104 O2, 40 CO2
Body tissue - 45 CO2
Pulmonary arteries and systemic veins - 40 O2, 45 CO2
Exhaled air - 120 O2, 27 CO2


Features of haemoglobin

- 4 polypeptide chains
- 4 Heme groups with iron atom
- can carry 4 oxygen molecules each
- as the number of oxygen molecules that are already bound increases, the ease of binding another O2 increases too (works in reverse too with unloading)
- first on or first off is the hardest


Partial pressure of O2 and subsequent O2 saturation of hemoglobin in:
- tissues during exercise
- tissues at rest
- the lungs

What does this imply?

pp O2 = 100%
sat = 100%

Tissues at rest
pp O2 = 40%
sat = 70%
30% oxygen offloaded to tissues

Tissues during exercise
pp O2 = 10 - 15%
sat = 80% oxygen offloaded to tissues


What does a decrease in pH imply for haemoglobin?

Hemoglobin retains less O2 at a lower pH, so at the same partial pressure, the O2 saturation of hemoglobin is less when pH is lower.


What occurs to diffusion as the size of an animals increases? How is this overcome?

Diffusion becomes inefficient as the time it takes for O2 to diffuse is proportional to the square of the distance it diffuses.
Circulatory systems overcome this.


Open vs closed circulatory systems

- blood is pushed down between organs into the haemolymph in the sinuses (the gaps)
- CO2 waits in the sinuses and is picked up by the blood there
- O2 delivered to sinuses and picked up by cells from there
- tubular heart
- insects
- one fluid
- simple, easy to maintain
- less energy and less pressure

- 2 fluids - interstitial (around and between organs) and blood
- blood never leaves circulatory systems
- diffusion of gases across blood vessel membranes to interstitial fluid and back
- higher pressure, results in increased efficiency for meeting high metabolic demand


Single vs double (amphibian) vs double (mammal) circulation

- 1 circuit
- fish
- blood from heart to gills to body to heart

- 2 circuits: one to lungs and one to body
In amphibians
- some mixing of blood as there is only one ventricle
- pulmocutaneous circuit includes lungs and skin capillaries

In mammals
- no mixing of blood at all as circuits are kept seperate by 2 ventricles


2 heart value types and location

Atrioventricular (AV) values - between atria and ventricles

Semilunar values - between ventricles and arteries (aorta and pulmonary artery)


Where are bicuspid and tricuspid values found?

Bicuspid - left
Tricuspid - right


Systole vs diastole

systole - contraction/pumping
diastole - relaxation/filling


What is cardiac output?

Heart rate (beats per min) x stroke volume (L per beat) = L/ per min


3 muscle types and features

Skeletal - voluntary and striated
Cardiac - involuntary and striated
Smooth - non-striated


What are pace maker cells?

Self-excitable cells that can generate an action potential without the brain. They pass on the AP to nonpacemaker cells via gap junctions between them


Artery vs vein vs capillary

All made of similar tissue and three similar layers, but are arranged in different ways.

- inner layer: endothelium, thick smooth muscle and thick connective tissue to withstand high pressure
- elastic: expand in systole and reduce in diastole

Vein -
- endothelium, thinner smooth muscle and thinner connective tissue as pressure is less
- lots of values to prevent backflow as blood is often going against gravity
- skeletal muscle contraction aids blood flow back to heart

- endothelium, basal lamina
- thinner outer layer to allow diffusion and exchange of gases to occur


How do lipid soluble substances such as oxygen and carbon oxide cross the capillary wall?

pass through the endothelial cells


How do plasma proteins cross the capillary wall?

generally cannot cross the capillary wall


How do exchangable proteins cross the capillary wall?

vesicular transport


How do small water soluble substances such as sodium and potassium ions, glucose and amino acids cross the capillary wall?

through the water-filled pores


How does the difference between osmotic pressure and blood pressure drive fluids out and into the capillaries?

Osmotic pressure is constant. Blood pressure decreases from arteriole to venule end.

At the arteriole end of a capillary, blood pressure is greater than osmotic pressure so fluid flows out of the capillary into the interstitial fluid.
At the venule end of a capillary, blood pressure is less than osmotic pressure so fluid flows from the interstitial fluid into the capillary.

This is due to fluid moving from high pressure to low pressure. Wherever the pressure is lowest - in the capillary (osmotic) or in the blood (blood) - is where the fluid will flow.


2 mechanisms that regulate the distribution of blood in capillary beds

Contraction of the smooth muscle layer in the wall of an arteriole to constrict the vessel

Contraction of precapilllary sphincters to control the flow of blood between arterioles and venules


Blood vs systolic vs diastolic pressure

Blood pressure - the hydrostatic pressure that blood exerts against the wall of a vessel

- the pressure in the arteries during ventricular systole
- the highest pressure in the arteries

- the pressure in the arteries during diastole
- lower than systolic pressure


Laminar vs turbulent flow

laminar - straight, does not create sound

Turbulent - not straight, can be heard as blood hits vessel wall


Vasoconstriction vs vasodilation

Vasoconstriction - narrowing of vessel as smooth muscle contracts causing upstream increase in blood pressire

Vasodilation - increase in vessel diameter as smooth muscle relaxes, decreasing blood pressure


3 constituents of blood and % volume

Red blood cells - 45%
Plasma - 55%
'Buffy coat' (platelets and white blood cells) ~1%


4 constituents of plamsa and function

Water - solvent

Ions (blood electrolytes) - osmotic balance, pH buffering and regulation of membrane permeability

Plasma proteins

Substances transported by blood


4 Plasma proteins



What is the function of the plasma protein Albumin?

osmotic balance and pH buffering


What are the plama proteins immunoglobulins are what are their function?

antibodies - defence


What is the function of the plasma protein apolipoprotein?

lipid transport


What is the function of the plasma protein fibrinogen?



3 blood cell types and their functions

Leukocytes (white blood cells)
- defence and immunity

- blood clotting

Erythrocytes (red blood cells)
- transport of O2 and some CO2


Abundance of erythrocytes

5 to 6 million per micro L (cubic millimetre)


Abundance of platelets

250 000 to 400 000 per micro L (cubic millimetre)


Abundance of leukocytes

5 000 to 10 000 per micro L (cubic millimetre)


Lymphoid stem cells vs myeloid stem cells

- lymphocytes
- B and T cells

All other cell types:
- erythrocytes
- neutrophils
- basophils
- monocytes
- platelets
- eosinphils


Lifespan of erythrocytes

3 to 4 months


5 types of Leukocytes



Where is average blood pressure lowest in the circulatory system?

Venae cavae


What would happen in the long term if the lymphatic vessels associated with a capillary bed were to become blocked?

Fluid would accumulate in interstitial areas


How is most CO2 carried from body tissues to the lungs?

As bicarbonate ions (HCO3-)


What is the Bohr shift produced by?

Changes in blood pH (lowering)


How does cardiac muscle differ from other types of muscle?

It contains branched cells.