Module 3 Flashcards
What are the common features of an effective exchange surface?
High surface area
Thin layers
Good blood supply/counter current (if applicable)
Which specialised cells can be found lining the trachea?
Ciliated epithelial cells (columnar) and Goblet cells
Describe the process of inspiration
Diaphragm and external intercostal muscles contract, increasing the volume of the lungs
Describe the process of expiration
The muscles relax, which is passive. In a heavy expiration internal intercostal muscles contract
Define vital capacity
The total volume minus the residual volume
Define tidal volume
The volume of air breathed in or out during a normal breath
Define inspiratory reserve volume
Volume of maximum possible inspiration (excluding the tidal volume)
Define expiratory reserve volume
Volume of air left in the lungs after the maximum possible expiration (excluding the tidal volume)
How do you calculate Ventilation Rate?
Tidal volume multiplied by breathing rate
Describe the anatomy involved in insect ventilation
Spiracles (with sphincters) connected to tracheae and then into tracheoles - which are bathed in tracheal fluid. If the insect wishes to exchange more gas, it withdraws the fluid to allow more oxygen to dissolve
Which direction does the water flow over gill lamellae?
From the efferent vessel toward the afferent vessel (in the opposite direction of blood flow)
What is the bony flap called that goes over the gills?
Operculum
How does a fish force water over its gills?
Fill the buccal cavity with water, close the mouth and contract the cavity as it opens the operculum
What is ram ventilation?
Constantly moving with an open mouth and operculum in order the induce gas exchange. Conducted by sharks
Name two adaptations that gills have to make gas exchange efficient
Tips of adjacent gill filaments overlap
Water flows in the opposite direction to the blood
What is the name of the body cavity which open circulatory system pump blood into?
Haemocoel
What is insect blood called, and what properties does it have?
Haemolymph, it carries only food and waste, and is often green or yellow
What is the main difference between an open and closed circulatory system?
Closed systems are quicker and carry blood at higher pressures
Describe the composition of arteries
Small lumen, and a thicker elastic and collagen layer (to withstand recoil), some also have smooth muscle to regulate vasodilation and vasoconstriction
Describe the composition of veins
Larger lumen, and lots of collagen, not much smooth muscle, and some have no elastin
How do veins prevent backflow?
Some have valves and some run near large, active muscles to help squeeze blood through them
Describe the basic composition of the blood
About 55% plasma, and the rest is made up of platelets, erythrocytes and leucocytes etc.
Describe the pressure changes at the arterial end of a capillary
Hydrostatic Pressure is higher than oncotic pressure, which forces the net flow of the fluid out of the capillary
Describe the pressure changes at the venous end of a capillary
Hydrostatic Pressure is lower than the oncotic pressure which forces the net flow of the fluid into the capillary
Describe the structure of Haemoglobin
Made of 4 subunits (2 alpha and 2 beta) that each carry one oxygen molecule. One erythrocyte can contain 300 million molecules of Haemoglobin
What is meant by the Positive Cooperativity of Haemoglobin?
It changes shape each time oxygen associates to a subunit to increase its affinity for the next molecule
What is the Bohr Shift?
At higher partial pressures of carbon dioxide, haemoglobin dissociates its oxygen more readily and the oxygen dissociation curve moves to the right
Which globular proteins in the body have a higher affinity for oxygen than Haemoglobin?
Myoglobin and Foetal-Haemoglobin
What is the enzyme called that catalyses the conversion of carbon dioxide and water into carbonic acid?
Carbonic Anhydrase
What is the Chloride shift?
Movement of chloride ions into a molecule of haemoglobin to compensate for the charge gradient caused by the Hydrogen-carbonate ions moving out
Which side of the heart houses the tricuspid atrio-ventricular valve?
The (patient’s) right side
What is the name of the tissue that conducts electrical impulse down the septum of the heart, to the apex?
Purkyne fibres
Which ventricle wall is thicker, and why?
The left, it has to pump blood (at pressure) around the entire body
What causes the ‘lub-dub’ heart sounds?
The closure of the atrio-ventricular and semilunar valves respectively
What special feature does cardiac muscle have?
It is myogenic - it holds its own natural rhythm
What is bradycardia?
Heart rate too slow
Why do organisms need transport systems?
To meet metabolic demands
Because of their large size
Because of their small surface area to volume ratio
In cross sections and transections of plant tissue, where can the xylem be seen?
In the vascular bundle, toward the centre or top, next to the phloem
Describe the immediate structure of Xylem and which tissues surround it
Xylem is a mostly-dead tissue made of lignin, it is surrounded by parenchyma and tannin - which is a bitter chemical which deters herbivory. It contains scars where end-cells have fused also
What connects the phloem and companion cells?
Plasmodesmata
What is the Apoplast pathway?
Movement of water through the cell walls of cells
What is the Symplast pathway?
Movement of water through the cytosol and plasmodesmata of cells
What is the role of the Casparian strip?
Waterproof layer that blocks the Apoplast route, forcing the water to take the Symplast route, filtering out any toxins
What evidence is there to support that endodermal cells actively pump minerals into the xylem, in order to change the water potential and draw water in?
Metabolic poisons (like cyanide) halt movement Root pressure increases alongside temperature Guttation (cutting xylem) shows sap leaking out
What is Transpiration?
Net water loss in a plant, from the opening of stomata and evaporation
What is the Transpiration Stream?
The path of the flow of water through a plant, from the roots up to the stomata
What evidence is there to support the Cohesion-Tension Theory
High rates of transpiration shrink tree-diameters
Broken Xylem vessels draw air in, not water out
Which plant cell primarily controls transpiration?
Stomata
What factors affect transpiration?
Light intensity Relative humidity Temperature Air-movement Soil-hydration
Name two common assimilates of translocation
Sucrose and amino acids
How is sucrose loaded into the phloem?
Co-transport on hydrogen ions. ATP pumps hydrogen out and it ‘diffuses’ back in with sucrose attached
What evidence is there that supports the translocation theory?
Advances in microscopy
Translocation stops in mitochondria are poisoned
The flow is faster that diffusion alone could be
Pressure in the phloem forces sap out of stylets
What adaptions do Xerophytes have?
Think waxy cuticle Less or sunken stomata Small leaf surface area Curled or Hairy leaves Succulents - store water in special parenchyma
What adaptations do hydrophytes have?
Thin (or no) waxy cuticle
Stomata on upper surfaces
Reduced structural support
Wide, flat leaves
Air sacs to help leaves float
Aerenchyma, parenchyma with apoptic air spaces
Pneumatophores, root nodules that grow into the air to aid gas exchange
What are lenticels?
Special sites on the stem or root that act like stomata