Download Unit 1 PIG - Mrs Miller`s Blog

• What features does a good exchange
surface have? 4
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Large sa
Thin barrier
Fresh supply of molecules
Removal of molecules
• How are the lungs adapted for gas
exchange? 5
• Large sa
• Permeable plasma membrane of cells in
alveoli
• Thin barrier- alveoli wall one cell thick
• Thin capillary wall
• Diffusion gradient maintained by breathing
and blood movement to and from lungs
• How is a diffusion gradient maintained in
the lungs? 2
• Breathing replenishes oxygen
concentration in alveoli
• Heart pumps blood away from lungs
lowering oxygen content in capillaries
Describe the role of cartilage, smooth
muscle, elastic fibres, goblet cells and
ciliated epithelium 5
• Cartilage: structural, prevents collapse
with pressure changes
• Smooth muscle: contracts to make lumen
narrower
• Elastic fibres: elastic recoil after smooth
muscle has contracted
• Goblet cells: secrete mucus
• Ciliated epithelium: move in synchronised
pattern to waft mucus up airway
Explain how size, surface area to volume
ratio and level of activity affect the need
for a transport system 3
• Size: bigger = more need for exchange
surface
• Sa: smaller = more need for exchange
surface
• Level of activity: more = more need for
exchange surface
• Explain the differences between single
and double circulatory systems 3
• Single = blood goes through heart once
with each circuit of the body
• Double = systemic and pulmonary
circulation.
• Blood visits heart twice with each circuit
through the body
• Describe the advantages of a double
circulatory system 2
• Increased pressure, so blood flows faster
• Systemic circulation can carry blood at
higher pressure than pulmonary circulation
• Explain the role of the valves and the
septum 2
• Valves prevent backflow
• Septum prevents oxygenated and nonoxygenated blood from mixing
Outline the stages in the cardiac cycle 3
• Filling phase: diastole, all parts are
relaxed, atrioventricular valves are open
• Atrial systole: atria contract pushing blood
into ventricles, semi lunar valves are
closed
• Ventricular systole: ventricles contract,
atrioventricular valves close, semi-lunar
valves open
• Describe how valves work 3
• Pressure in ventricles drops below atria
• Atrioventricular valves open
• Ventricle fills with blood and increase in
blood pressure fills the valve pockets and
closes atrioventricular valves
• Explain how heart action is co-ordinated 5
• SAN generates electrical activity
• Spreads over atrial walls causing
contraction
• AVN delays the signal
• Passes it down purkyne tissue
• Up from the base of the heart causing
ventricles to contract
1. Explain the differences between open
and closed circulatory systems 2
• Open: blood is not contained in vessels, in
insects it enters heart through ostia and
blood is pumped by peristalsis
• Closed: blood is contained in vessels
• Describe the structure of arteries, veins
and capillaries 3
• Arteries: small lumen, thick wall, elastic
fibres, smooth muscle, contains collagen
• Veins: large lumen, inner layers of
collagen, smooth muscle, elastic tissue, no
stretch or recoil, valves
• Capillaries: thin walls, single layer of cells,
narrow lumen
• Outline the role of blood, tissue fluid and
lymph 3
• Blood: transport oxygen, hormones and
carbon dioxide
• Tissue fluid: plasma with dissolved
nutrients and oxygen, speeds up diffusion
• Lymph: contains lymphocytes and filter
bacteria and foreign materials for
destruction
• Explain how tissue fluid and lymph are
formed 2
• Tissue fluid: high hydrostatic pressure
pushes blood fluid out of the capillaries
through tiny gaps
• Lymph: some tissue fluid is drained into
lymphatic vessels
• Describe the role of haemoglobin in
carrying oxygen 4
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4 subunits
Haem contains one iron atom
Haem has affinity for oxygen
Oxyhaemoglobin releases oxygen=
dissociation
1. Explain the oxygen dissociation curve
and explain why the curve for fetal
haemoglobin is different 2
• Oxygen dissociation: S shaped curve, as
oxygen tension rises, more haemoglobin is
saturated, then curve levels off
• Fetal haemoglobin has a higher affinity so
that it can absorb oxygen from mothers
blood
• How are hydrogencarbonate ions formed?
3
• CO2 combines with water to make
carbonic acid
• Carbonic acid dissociates to release
hydrogen ions and hydrogencarbonate
ions
• They diffuse out of the red blood cells into
the plasma
• What is the chloride shift? 1
• Chloride ions (negative) move from
plasma into the red blood cells, to maintain
the charge as negative
hydrogencarbonate ions have left
• Outline the Bohr effect 3
• Hydrogen ions released from dissociation
of carbonic acid
• Hydrogen ions displace the oxygen in
haemoglobin
• Oxyhaemoglobin releases more oxygen to
tissues
1. Describe the distribution of xylem and
phloem in the root, stem and leaf 3
• Root: x shaped xylem
• Stem: xylem and phloem in circles near
outside of stem
• Leaf: xylem above phloem
• Outline the structure of xylem and phloem
• Xylem: continuous column, dead cells,
lignified, pits
• Phloem: sieve tube elements, companion
cells, perforated sieve tubes
1. Describe the meaning of water potential
and how it affects a plant cell
• Water potential is the movement of water
down a concentration gradient: affected by
pressure and solutes
• Plasmolysed, turgid, flaccid
• Outline how water can move between cells
• Apoplast: between cell walls
• Symplast: through plasma membrane
• Vacuolar: through cytoplasm and vacuole
• Explain how water moves up the stem
• Cohesion-tension theory
• Transpiration pull and capillary action
• Outline the factors that affect the rate of
transpiration (8)
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Number of leaves
Number of stomata
Cuticle,
Light
Temp
Humidity
Air movement
Water availability
• How do plants cope in arid conditions
(how are they adapted?)
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Rolled leaf
Thick cuticle
Trapped air inside rolled leaf
Hairs on lower surface
Stomata in pits
• Explain how sugars are transported along
the phloem tissue 2
• Translocation
• from source to sink
• Explain the meaning of sources and sinks
with examples of each
• Source: loads sucrose
• Sink: uses/stores sucrose
• Leaf/root