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OCR Biology A Level Module 3 > 3.2 Transport in animals > Flashcards

3.2 Transport in animals Flashcards

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1
Q

What is the need for a transport system?

A
  • if diffusion distance is too large and so diffusion only isnt efficient enough to supply all tissues with glucose and oxygen for example
  • if metabolic activity is high
  • if SA:V ratio is too small
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2
Q

What are the features of a good transport system?

A
  • Fluid/medium: carry nutrients, O2 + waste = BLOOD.vMaintains concentration gradient
  • Pump to create pressure = HEART
  • Exchange surfaces that enable substances to enter and leave the blood = CAPILLARIES
  • Tubes/vessels to carry blood by mass flow (which is movement of fluids down a pressure gradient)
    -Two circuits: one to pick up O2 and one to deliver O2
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3
Q

What is the difference between single and double circulation?

A

Single = Blood flows through heart once for each circuit of the body. Slower delivery rate since pressure needs to be low near thin gills, this suffices due to low metabolic rate.

Double = Blood throws through heart twice for each circuit. Pulmonary: deoxygenated to PICK up O2. Systemic: oxygenated. Blood pressure must not be too high in pulmonary, but after lungs can increase = FASTER FLOW = allows for higher metabolic activity.

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4
Q

What is an open circulatory system? What are the disadvantages?

A
  • fluid in body cavity, not vessels-> HAEMOLYMPH.
    -movement of body, or blood enters ostia and muscular pumping organ pumps it to the head by peristalsis.
  • blood pours into haemocel. Heart relaxes = haemolymph sucked back into heart.
  • Active: open-ended tubes to direct to active body parts.

DISADV: LOW PRESSURE AND AFFECTED BY MOVEMENTS.

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5
Q

WHat is a closed circulatory system and what are the advantages?

A

In vessels
Blood pressure is higher, rapid delivery, independent of body movements

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6
Q

What do all blood vessels have and why?

A

ENDOTHELIUM to reduce friction

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7
Q

What are the features of arteries?

A
  • Small lumen: maintain pressure
  • Tunica intima: thin elastic tissue - recoil to maintain pressure
  • Tunica media: thick smooth muscle to contract
  • Tunica adventitia: thick collagen for support and elastic layer to withstand pressure
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8
Q

What are the features of arterioles?

A
  • Small
  • Smooth muscle to constrict + dec flow rate
  • Divert blood to high demand areas
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9
Q

What are the features of veins?

A
  • Large lumen so low friction
  • Thin muscle, thin elastic - no need to recoil
  • Collagen for support
  • Valves: vein flattened by skeletal muscle + applies pressure -> forces blood in the direction
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10
Q

What are the features of venules?

A
  • Small
  • Thin layers of muscle, elastic and thin outer collagen layer
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11
Q

What are the features of capillaries?

A
  • narrow lumen
  • RBCS squeezed
  • thin, leaky walls
  • no elastic/muscle tissue
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12
Q

What is in blood vs tissue fluid?

A

Blood: plasma, blood cells, dissolved substances, O2, CO2, glucose, platelets, amino acids.
Tissue fluid: no plasma proteins, doesnt contain most cells found in blood. lymphocytes. Carries dissolved substances, some returns to capillaries and some drained into lymphatic system, or enters cells.

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13
Q

How do fluids move through the capillaries? What is hydrostatic and oncotic pressure?

A
  • Hydrostatic: Pressure from the volume of blood
  • Oncotic: plasma proteins in blood, too large to pass through gaps, therefore water potential is lowered and water moves into capillaries by OSMOSIS.

At arteriole: hydrostatic is GREATER than oncotic, so blood fluid pushed out.
At venule: hydrostatic is LESS THAN oncotic since lots of fluid has been moved out already, so fluid moves back in.

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14
Q

Where does some of the rest of the tissue fluid go? Features of lymph?

A
  • LYMPHATIC SYSTEM -> draining excess. Returns it to blood system in SUBCLAVIAN vein in chest.
  • FLuid is LYMPH: low hydrostatic pressure, lymphocytes, few proteins, more fats
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15
Q

What is the role of the AV and semi-lunar valves?

A
  • AV: prevent backflow of blood into atria
  • Semi-lunar: prevent blood returning to heart as ventricles relax
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16
Q

What is the role of the tendinous cords?

A
  • Attach valves to muscle and prevent turning inside out when ventricles con
17
Q

What are the external features of the heart?

A
  • Coronary arteries: supply oxygenated blood to heart muscle. Blockages = myocardial infarction often.
  • Number of blood vessels on top -> veins into atria and arteries carrying blood away
18
Q

How does the wall thickness differ between the atria, LV, and RV?

A

Atria: THIN. No need for high pressure.
RV: Thicker than atria, but not too high pressure because of delicate alveoli.
LV: Much thicker than right ventricle since its going to the rest of the body.

19
Q

What are the stages of the cardiac cycle?

A
  1. AV DIASTOLE: Relaxation and elastic recoil = chambers inc in volume. Pressure dec + pressure of ventricles dec even more. Blood flows into atria also slowly into ventricles.
  2. ATRIAL SYSTOLE: contraction.AV valves open, Ventricles fill more. AV valves close when full.
  3. VENTRICULAR SYSTOLE: contract. Pressure inc above that of arteries so blood moves up and SEMI-LUNAR VALVES OPEN. Blood moves into aorta and arteries.
  4. VENTRICULAR DIASTOLE: relaxes. Blood flows back to ventricles a bit and is collected at valve pockets = SEMI-LUNAR VALVES PUSHED CLOSED.
20
Q

How is the cardiac cycle coordinated?

A
  1. SAN generates wave of excitation that spreads over walls of both atria -> contract
  2. AVN at top of septum has a delay so ventricles can fill. Wave of excitation carried down Bundle of His and Purkyne tissue
  3. At base the wave spreads over ventricle walls -> contract from apex upwards which pushes blood up to arteries.
21
Q

What is the role of haemoglobin?

A
  • Fe2+ high affinity for oxygen, each can carry 4O2
  • O2 binds reversibly = oxyhaemoglobin. ASSOCIATED.
  • Oxyhaemoglobin releases O2 in tissues. DISSOCIATED.
22
Q

Explain the shape of the oxygen dissociation curve

A
  • Tissues = low pO2, low affinity and low saturation
  • One associates = confirmational change = easier to associate
  • Lungs = high pO2 = higher saturation.
23
Q

What is the difference with fetal haemoglobin?

A
  • Curve to LEFT due to higher affinity at most kPa, so can associate with oxygen at partial pressures adult haemoglobin wouldnt.
  • Must be able to associate in placenta where pO2 is low, and also where the fetus is respiring = CO2 released.
    -Oxygen diffuses into placenta -> decreases pO2 in maternal blood -> more dissociation from adult haem.
24
Q

What is the Bohr Effect?

A
  • Curve shifted to the right in high pCo2 areas due to lower affinity of haemoglobin for oxygen
25
Q

What happens at tissues and lungs in terms of CO2?

A

Tissues: carbon dioxide and water -> carbonic acid -> H+ and HCO3-. pH decreases and haemoglobinic acid forms. Lower affinity and O2 dissociates.
CHLORIDE SHIFT = movement of Cl- ions

Lungs: Conc of CO2 decreases in RBC so more carbonic acid dissociates into carbon dioxide and water. Carbonic acid combines with H+ more. pH increases and tertiary structure changes = higher affinity.

26
Q

What is the P wave?

A

Caused by the depolarisation of the atria, which results in atrial contraction (systole)

27
Q

What is the QRS complex?

A

Caused by the depolarisation of the ventricles, which results in ventricular contraction (systole)
This is the largest wave because the ventricles have the largest muscle mass

28
Q

What is the T wave?

A

Caused by the repolarisation of the ventricles, which results in ventricular relaxation (diastole)

29
Q

What is tachycardia?

A

high heart rate

30
Q

What is bradycardia?

A

low heart rate

31
Q

What is ectopic heartbeat?

A

early heartbeat

32
Q

What is atrial fibrilliation?

A

uncoordinated heart beat/irregular

OCR Biology A Level Module 3 (3 decks)

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