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Biology Alevel > Transport In Animals > Flashcards

Transport In Animals Flashcards

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1
Q

Why do larger organisms require specialised mass transport systems?

A

Increased transport distances
- exchange sites tend to be far away from other cells - large transport distance means diffusion not efficient as a transport system

Smaller SA:V ratio
- less SA For absorption of nutrients/gases
- more volume = longer diff distance to cells/tissues
Therefore, diffusion not efficient

Higher metabolic rate
- more demand for O2/nutrients - diffusion not efferent enough to meet demands

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2
Q

What are the 2 models of circulatory systems?

A

Single circulatory system- blood passes through the heart once during one complete circuit of the body
double circulatory system - blood passes through the heart twice during one complete circuit of the body

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3
Q

Explain the single circulatory system in fish?

A
  1. Deoxgenated blood pumped from HEART —> GILLS
  2. Gills are exchange site - blood becomes OXYGENATED
    flows from GILLS —> REST OF BODY
  3. Blood RETURNS TO HEART (has one atrium/one ventricle)
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4
Q

Explain double circulatory system in mammals?

A

Have left side/right side to deliver oxygenated/ deoxygenated blood
- blood on RHS —> LUNGS (pulmonary circuit)
- LUNGS —> LHS
- LHS —> REST OF BODY (systemic circuit)
- BODY —> RHS

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5
Q

Heart?

A

Hollow, muscular organs in chest cavity that pumps blood

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6
Q

Artery and arterioles?

A

Arteries : blood vessels that carry bloo away from heart
Arterioles : smaller arteries that branch from larger arteries/connect capillaries

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7
Q

Capillaries?

A

Tiny blood vessels that connect arterioles/venules

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8
Q

Veins and venules?

A

Veins - blood vessels that carry blood to heart
Venules - small veins that join capillaries to larger veins

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9
Q

Advantages of double circulation?

A
  • Blood only passes through one capillary network before returning to the heart
    So :
    the double circulation maintains higher blood pressure and average speed of flow
    Therefore, helps to maintain a steeper concentration gradient - efficient exchange of nutrients and waste with the surrounding tissues
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10
Q

What is an open and closed circulatory ssystem?

A

CLOSED : blood pumped around body/contained in a network of blood vessels

OPEN : blood not contained in blood vessels but pumped directly into body cavities

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11
Q

Structure of arteries?

A

Walls consist of 3 layers
TUNICA ADVENTITIA/EXTERNA: covers exterior of artery - COLLAGEN
- protect blood easels from damage by overstretching
TUNICA MEDIA:
smooth muscle cells: withstand high pressure /enable contract/narrow lumen
thick layer of elastic tissue - maintain blood pressure - stretches and recoils to even out fluctuations in pressure
TUNICA INTIMA: endothelial layer (one cell thick)
layer of connective tissue
layer of elastic fibres

Narrow lumen /pulse is present

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12
Q

Structure of arterioles?

A
  • muscular layer- can contract /partially cut off blood flow to specific organs
  • lower proportion of elastic fibres
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13
Q

Structure of veins?

A

Tunica media is thinner
- thinner muscular wall - don’t need to withstand high pressure

More collagen than arteries: structural support to hold larger vol of blood

Lumen is larger - ensures blood returns to heart at an adequate speed
- reduces friction between the blood and the endothelial layer of the vein

Has valves /no pulse

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14
Q

Structure of venules?

A

Large lumen
Few/no elastic fibres

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15
Q

structure of capillaries?

A

Very small diameter- forces the blood to travel slowly - allows for diffusion to occur
- only large enough for RBCs to pass in single file
Branch between cells - allow diffusion between cells and blood - short diff distance
Wall made from endothelial cells (1 cell thick) - reduce diff distance
- cells of wall have PORES: allow blood plasma to lead out/form tissue fluid

No muscle /elastic tissue

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16
Q

Explain tissue fluid formation?

A

At arterial end:
Hydrostatic pressure > osmotic pressure
- fluid moves out capillary
- proteins remain in blood as too large - creates WP GRADIENT between capillary and tissue fluid

At venous end:
Hydrostatic pressure in capillary reduced as INCREASED DISTANCE FROM HEART /SLOWER BLOOD FLOW when in capillaries
Osmotic pressure > hydrostatic pressure*
- water flows back into capillary from tissue fluid
WP GRAD is same as it was in arterial end

10% of tissue fluid doesn’t return back to capillary/ remains as tissue fluid - collected by LYMPH VESSELS and returned to circulatory system

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17
Q

What causes Oedema?

A

If BP is high , then pressure at arterial end is GREATER
- pushes MORE FLUID OUT of capillary/fluid accumulates around tissues

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18
Q

What is hydrostatic and oncotic pressure?

A

HYDROSTATIC : pressure exerted by fluid
E.g blood pressure

ONCOTIC : osmotic pressure exerted by plasma proteins in blood vessel
- proteins lower WP so water moves into blood vessel by osmosis

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19
Q

What is plasma and tissue fluid?

A

Plasma - straw colour liquid that constitutes 55% of blood
- good solvent as mostly water
Tissue fluid : when plasma leaks out through gaps in walls of capillary and surrounds cells of body

20
Q

Structure of lymph vessels? How is liquid moves along these vessels?

A
  • Closed ends
  • large pores that allow larger molecules to pass through
  • have small valves in vessel walls
  • liquid moves along by compression caused by body movement / backflow prevented by valves
21
Q

Purpose of lymph/lymph vessels?

A
  • Larger molecules that are not able to pass through capillary wall enter lymphatic system as LYMPH
  • can return any plasma proteins that have escaped blood , back into blood
22
Q

Difference in composition of tissue fluid vs plasma?

A

Plasma has :
Higher conc of GLUCOSE
Higher conc of GLYCEROL/FATTY ACIDS
Higher conc of PLASMA PROTEINS
A lower water potential

23
Q

Pathway of blood through the heart?

A

VENA CAVA —> RA —> AV valve (tricuspid)—> RV —> Semi lunar valve —> pulmonary artery —> LA —> AV valve (bicuspid)—> LV —> Semi Lunar Valve —> Aorta

24
Q

Cardiac cycle? What is systole and diastole?

A

Series of events that take place in one heart beat , including muscle contraction/relaxation

Systole = contraction of heart
Diastole = relaxation of heart

25
Q

What happens in atrial systole?

A

Walls of atria CONTRACT / ventricles relax
- Atrial volume decreases
- Atrial pressure increases
pressure in the atria > pressure in ventricles, forcing (AV) valves open
- Blood is forced into the ventricles - pressure in ventricles increase a bit

26
Q

What happens in ventricular systole?

A

walls of ventricles contract/ Atria relax (atrial diastole)
- Ventricular volume decreases
- Ventricular pressure increases
pressure in the ventricles > pressure in atria
- forces the AV valves to close, preventing back flow of blood
pressure in the ventricles > pressure in aorta/ pulmonary artery
- forces the SL valves open

27
Q

What happens in diastole?

A

The ventricles and atria are both relaxed
pressure in the ventricles < pressure in aorta and pulmonary artery, forcing the SL valves to close

Blood returns to the heart via the vena cava and pulmonary vein/ atria fill with blood
Pressure in the atria > pressure in ventricles, forcing the AV valves open - Blood flows passively into the ventricles without need of atrial systole
The cycle then begins again with atrial systole

28
Q

What is cardiac output? Equation?

A

Volume of blood that is pumped by heart per unit time

CO= Heart Rate x Stroke volume

29
Q

What is heart rate and stroke volume?

A

HR : number of time a heart beats per minute
Stroke Volume: plume of blood pumped out the Left Ventricle during one cardiac cycle

30
Q

Myogenic?

A

Heart will beat without any external stimulus

31
Q

How is heart rate /rhythm controlled?

A

Sinoatrial node (SAN) : cells in RA
- initiates wave of depolarisation —> causes ATRIA TO CONTRACT
- reaches collagen fibres which prevents depolarisation spreading to ventricles straight away (DELAY - Allows ventricle to fill with blood/contract after atria)

Depolarisation carried to Atrioventricular node (AVN)
- AVN passes stimulation along BUNDLE OF HIS (conducting tissue in septum )
Divides into 2 conducting fibres - PURKYNE TISSUE / carries wave of excitation along them

Pukyne fibes spread around ventricles/initiate depolarisation of ventricles from bottom of heart —-> VENTRICULAR SYSTOLE ( blood pushes upwards/outwards)

32
Q

Explain ECG diagrams?

A

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

The QRS complex
Caused by the depolarisation of the ventricles, which results in ventricular contraction (systole)
- largest wave as ventricles have the largest muscle mass

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

33
Q

What is Tachycardia , Bradycardia , Ectopic Heartbeat and fibrillation?

A

Tachycardia : heart beats too fast (evenly spaced)
>100 bpm

Bradycardia : heart beats too slow (evenly spaced)
<60 bpm

Ectopic HR : early heartbeat followed by pause

Fibrillation : irregular heartbeat - disrupt rhythm of HR
- no P wave present - heart rate is controlled by SAN predominantly /its damaged in fibrillation

34
Q

Structure of haemoglobin?

A
  • contains 4 haem groups (containing iron) - each bond to molecule of O2
  • quaternary structure
    4 polypeptide chains
35
Q

Reaction between oxygen and haemoglobin?

A

Oxygen + Haemoglobin —> Oxyhaemoglobin
- reversible

4O2 + Hb —> Hb4O2

36
Q

3 ways CO2 is transported around body?

A
  • Small % dissolved in blood plasma / transported in solution
  • CO2 binds to haemoglobin —> carbaminohaemoglobin
  • larger % transported in form of hydrogen carbonate ions (HCO 3-)
37
Q

Formation of hydrogen carbonate ions?

A

CO2 diffuse from PLASMA —> RBCS

In RBCs , CO2 + H2O —> H2CO3 - combine with water to form CARBONIC ACID
- catalysed by CARBONIC ANHYDRASE - enzyme in RBCs

Carbonic acid dissociates :
H2CO3 —> HCO 3- + H+ ( into hydrogen carbonate ions and hydrogen ions)

H+ combines with haemoglobin = haemoglobinic acid - prevents H+ from lowering pH
- Haemoglobin is buffer

Hydrogen carbonate ions diffuse out RBC into plasma /transported in solution / chloride ions move into RBCs
- balance the charge

38
Q

What is an oxygen dissociation curve ? What is partial pressure of oxygen?

A

Shows rate at which oxygen associates and dissociates with haemoglobin at different partial pressures of oxygen

Partial pressure of oxygen is measure of oxygen conc

39
Q

Why is the dissociation curve an S-shape ?

A
  1. At first its difficult for oxygen to bind to haemoglobin due to its shape —> slower binding - shallow part at bottom
  2. After first molecule of O2 has binded , haemoglobin protein changes shape - conformational changes
    - easier for next O2 molecule to bind = FASTER BINDING - steeper part
  3. As haemoglobin approaches saturation , takes longer for 4th molecule to bind due to SHORTAGE OF BINDING SITES - levels off at top
40
Q

Explain the oxygen dissociation graph ?

A

At low pO2 : Haemoglobin has LOW AFFINITY for oxygen , so binds slowly/dissociates easier
- saturation of haemoglobin is LOW
- dissociation slows (bc few O2 molecules left on binding sites/release of last O2 molecule is most difficult)

At medium pO2: oxygen binds more easily to haemoglobin /saturation increases quickly
- small increase in pO2 = large increase in saturation
- dissociates readily

At high pO2:
- haemoglobin has HIGH AFFINITY for O2 at high pO2
So binds easily
so saturation of O2 is high
- little dissociation

41
Q

How and why is foetal haemoglobin different to adult haemoglobin?

A

Has higher affinity for oxygen than adult haemoglobin, at any partial pressure (dissociation curve moves left)
SO THAT:
- foetus can obtain oxygen from mother’s blood at placenta (which is low pO2) - can bind to oxygen as low pO2 by having higher affinity

After birth, adult haemoglobin replaces foetal - allows easy release of O2 for repairing tissues as larger metabolic rate

42
Q

What is the Bohr effect?

A

Describes the change in affinity for oxygen , haemoglobin has , due to increased partial pressure of CO2
- changes in dissociation curve - shift right (lower affinity for O2 at any pp)
- lower affinity = OXYGEN IS RELEASED FROM BLOOD - haemoglobin gives up its oxygen more readily
(When Hydrogen ions bind to haemoglobin - causes release of O2)

43
Q

Circulatory system in insects? Why do they have less efficient circulatory systems?

A
  • have one main blood vessel - DORSAL VESSEL
  • tubular heart pumps blood into dorsal vessel
  • dorsal vessel delivers blood to BODY CAVITY
    Blood surrounds ORGANS/reenters heart through valves called OSTIA
  • doesn’t need to have efficient circulatory system bc oxygen delivered to tissues via tracheae (in tracheal system)
44
Q

PRACTICAL : heart dissection

A

External examination:
- look at outside of heart /identify 4 main vessels
Feel inside vessels to help (arteries are thicker than veins)
Draw sketch of both ventricles and atria

Internal examination: cut along lines to look inside ventricles
- measure/record thickness of ventricle walls
- cut open atria/note whether they’re thicker/thinner than ventricles

Find AV/SL valves and look at structure
Draw sketch showing valves/inside of ventricles and atria

45
Q

Composition of tissue fluid compared to lymph ?

A

Both: no RBCS- remain in blood bc too large
No platelets
Very few proteins
Water/dissolved solutes
Lymph: WBCs/antibodies

Biology Alevel (24 decks)

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