Unit 2 (2.3) Flashcards
Adaptations for transport
Vascular systems of earthworms
Vascularisation, closed circulatory system and pumps, carriage of respiratory gases in blood
Vascular systems of mammals
Double circulatory systems
Vascular systems of fish
Single circulatory system
Vascular systems of Insects
Open circulatory system, dorsal tube-shaped heart, lack of respiratory gases in blood
What is a double circulatory system?
Circulatory system in which blood flows twice in two circuits, blood pumped from heart to lungs, returns to heart, pumped around body and returns to heart again.
What is a single circulatory system?
Circulatory system where blood travels through heart once in one circuit, blood flows through the heart and is pumped around the body before returning to heart.
Why is cardiac muscle describes as myogenic?
It initiates its own contraction without outside stimulation from nervous impulses.
Four chambers of mammalian heart
Left Atrium
Right Atrium
Left Ventricle
Right Ventricle
Five types of blood vessel
Arteries
Arterioles
Capillaries
Venules
Veins
Structures of mammalian heart
Left atrium
Right ventricle
Bicuspid valve
tricuspid valve
Pulmonary vein
Vena cava
Semi-lunar valve
Aorta
Pulmonary artery
What is the cardiac cycle?
The sequence of events involved in one complete contraction and relaxion of the heart
Three stages, atrial systole, ventricular systole and diastole
What is plasma?
Main component of the blood (yellow liquid) that carries red blood cells
Contains proteins, nutrients, mineral ions, hormones, dissolved gasses, and waste.
How does partial pressure of oxygen affect oxygen-haemoglobin binding?
Haemoglobin has variable affinity for oxygen depending on the partial pressure of oxygen, p(O2)
At high p(O2) oxygen associates for form oxyhaemoglobin
At low p(O2) oxygen dissociates to form deoxyhaemoglobin
Role of haemoglobin
Present in red blood cells. Oxygen molecules bind to the haem groups and are carried around the body, then released where they are needed in respiring tissues.
Why is the higher affinity of fetal haemoglobin important?
Enables the fetus to obtain oxygen from the mothers blood
Why does fetal haemoglobin differ form adult haemoglobin?
Higher affinity for oxygen than adult haemoglobin due to the presence of two different subunits that allow oxygen to bind more readily .
Compare the dissociation curves of adult and fetal haemoglobin
Fetal haemoglobin dissociation to the left. At the same partial pressure, % oxygen saturation is greater due to fetal haemoglobin having a higher affinity.
What is the chloride shift?
Process by which chloride ions move into the erythrocytes in exchange for hydrogen carbonate ions which diffuse out of the erythrocytes.
One to one exchange
Why is chloride shift important?
It maintains the electrochemical equilibrium inside the cell
What is the Bohr effect?
The loss of affinity of haemoglobin for oxygen as the partial pressure of carbon dioxide increases.
What is tissue fluid?
Fluid that surrounds the cells of animals
Same composition as plasma but does not contain red blood cells or plasma proteins.
How is fluid tissue formed?
Blood pumped through increasingly smaller vessels, hydrostatic pressure is greater than oncotic pressure, fluid moves out of the capillaries. Then exchanges substances with the cells.
Hydrostatic pressure
Higher at arterial end of capillary than venous end.
Oncotic pressure
Changing water potential of the capillaries as water moves out, induced by proteins in the plasma.
Structure of the dicotyledon root
Xylem arranged in x shape to provide resistance against force. Phloem found as patches between the arms. Surrounded by endodermis, aiding water passage.
Which structure in plants is adapted for the uptake of root water and minerals?
Root hair cells
Structure and function of endodermis
Innermost layer of the cortex of a dicot root
Impregnated with suberin which forms the casparian strip
Endodermal cells actively transport mineral ions into the xylem
Three pathways which water moves through the root
Apoplast pathway
Symplast pathway
Vacuolar pathway
Describe the symplast pathway
Water enters cytoplasm through the plasma membrane and moves between adjacent cells via, plasmodesma. Water diffuses down its water potential gradient by osmosis.
Describe the vacuolar pathway
Water enters the cytoplasm through the plasma membrane and moves vacuoles of adjacent cells. Water diffuses down it’s water potential gradient by osmosis.
What is the transpiration steam?
The flow of water from the roots to the leaves in plants, where it’s lost by evaporation to the environment.
Describe the apoplast pathway
Water moves through intercellular spaces between cellulose molecules in the cell wall. It diffuses down water potential gradient by osmosis.
How does water move up the stem?
Root pressure
Cohesion tension theory
Capillarity
Explain cohesion-tension theory
Water molecules form H bonds with each other, so they stick together
Surface tension of water creates this sticking effect
Therefore as water is lost it loses its transpiration, more is drawn up the stem from the roots
Factors that affect rate of transpiration
Light
Temperature
Humidity
Air movement
How does light affect rate of transpiration
High light increases rate of photosynthesis, causing more stomata to open for gas exchange, increasing rate of transpiration.
How does temperature affect rate of transpiration
Higher temperature increases , so does random motion and rate of evaporation, therefore increasing rate.
How does humidity affect rate of transpiration
Water content of the air next to leaf is high, reduces concentration gradient, decreases rate of transpiration
How does air movement affect rate of transpiration
Large amounts of air blow moist air away from the leaves, creating a steep concentration gradient. Increases rate.
What are cytoplasmic strands
Small extensions of cytoplasm between adjacent sieves tube elements and companion cells.
Function of cytoplasmic strands
Allow communication and exchange of materials between sieve and tube elements, and companion cells.
Hold nucleus in place
Define translocation
The movement of organic compounds in the phloem, from sources to sinks.
