5.4 The respiratory system Flashcards
What does the respiritory system consist of?
4 points
- 10 pairs of spracles leading to
- the trachea connected directly to
- the tracheal sacs and
- the tracheoles which lead to all [parts of the body particularly the muscles, glands and tissues where respiration takes place
What is the finction of the respiritory system?
- To provide a supply of O2 in order to release energy by respiration
- To rid the system of Co2 (waste product of energy production)
This gaseous exchange is acheived paertly by diffusion and mainly by muscular action of the abdominal segments where inergy is being used at a high rate.
Where are spiracles and what do they do?
External respiratory orifices in insects
- 10 pairs in total on T2, T3, A1 and A2 to A8
- A8 cannot be seen as it is hidden in the sting chamber
- All have valves except T3 which is small
- The valve on T2 cannot be fully closed (remember 2 wide) - n.b: acarine and is concealed below a flat lobe part of T1. The edge of the lobe is covered in dense hairs
- A1, the 3rd spiracle is the largest one of all (0.23mm to 0.6mm)
- There are two types of valve, the one on T2 and those on A1 to A8
- opening and closing of the spiracles is controlled by muscles. When a bee is seen to land the contraction and relaxation of the abdomen can be clearly seen, this is the bee drawing in and expelling oxygen and carbon dioxide.
What to the trachea do?
passages through which air is conveyed through the body of an insect
- major highways from the tracheal sacs
- a continuation of the ingrowths of the body wall and are fored of a thin epitheliom of flat cells which is lined with a cuticular intima
- The cuticular intima is ribbed with ckiseky set thickenings called taenidia which provide rigidity to the tracheal walls and prevents their collapse
- they provide the major outlets fro the tracheal sacs and provivde the distribution network in a branched formation of tubules that become smaller and smaller eventually terminating in the tracheoles
Name the three types of spiracles and describe how they work?
- The first spiracle on T2 has the trachea connecting directly to the spiracle membrane. The spiracle is
hidden under a spiracle lobe which is lined with fine hairs. The spiracle has an external closing
mechanism, the operculm, a sclerotized plate that does not fully cover the opening. The operculm is
controlled by an occlusor (closing) muscle which connects to a small arm beneath the spiracle
membrane. When the muscle contracts the operculm closes over the opening and when it relaxes
the operculm opens. - The 3rd spiracle on A1 (propodeum) has a long aperture of 0.23mm by 0.06mm when open. It is
surrounded by an elevated rim creating an external atrium. Within the entrance to the opening is
controlled by two muscles connected to a valve made up of a soft integumental fold with a strongly
sclerotized margin. The contraction of the occlusor (closing) muscle causes the valve to move
forward closing the aperature, the relaxing of the occlusor and contraction of the dilator muscle
causes the valve to release and reveal the aperature. - The Abdominal spiracle has an internal atrium lined with filtering hairs. A domed shaped valve lies
between the atrium and the trachea. Closing muscles move the valve towards the ridge and opening
muscles pull the valve away from the ridge thus exposing the trachea.
TMCD (Too Much Can Drench)
What is the function of haemolymph?
Transport of food materials to the cells of the body and the transport of waste products to the excretory system.
**Mechanical **support primarily in the larva as it does not have an exoskeleton, the support through contractions of muscles include the glossa and the endophallus of the drone. During moulting the haemolymph provides support whilst plates sclerotise. The balanced pressure of the haemolymph gives rigidity to the body parts, particularly the thorax. **Control of water content ** as the cells are bathed in haemolymph and the
concentration of the materials within the haemolymph are maintained within strict bounds the cells always have sufficient water for their processes. Haemolymph does not transport oxygen, rather it facilitates the dilution of the gases to assist transfer.
The haemolymph plays a role in the defence against pathogens, some proteins in the haemolymph (manufactured in fat bodies) will attack pathogens.
Two parts
Structure of haemolymph
- Plasma - colourless watery liquid carrying substances including salts, amino acids, proteins, carbs, uric acid, lipids, fattyu acids, etc.
- Haemocytes - colourless cells with nuclei suspended in the plasma
below 12, 12-15, above 28
How does temperature affect respiration?
- At 12°C or below - no abdominal ventilatory movements.
- 12-15°C the abdomen has intermittent abdominal movements
- Above 28°C the movement cycles can be 100 per minute.
What is ATP?
(adenosine triphosphate) is the energy-carrying molecule used in cells because it can release
energy very quickly.
ATP can transfer energy and phosphorylate (add a phosphate) to other molecules in cellular processes such as DNA replication, active transport, synthetic pathways and muscle contraction.
What are Mitochondria?
Structures in the cytoplasm of all cells where respiration takes place (singular is
mitochondrion).
What is glycolosis?
Occurs in cytoplasm.
The breakdown of glucose into two pyruvate (end product of glycolosis) molecules. This process is anaerobic (doesn’t need oxygen). The glucose undergoes a series of chemical transformations.
How does oxygen reach the internal organs of the bee when at rest?
When at rest, the abdomen moves to create respiratory movements, allowing the abdomen to expand and air sacs to fill with air due to greater outside pressure.
The muscles controlling these movements are linked to nerves from the ganglia, stimulated by carbon dioxide buildup.
What happens to the air sacs when the bee’s abdomen expands?
As the abdominal wall expands, the air sacs expand, allowing air to be pushed into them.
When the abdomen becomes smaller, air is pushed out of the sacs.
Where does most of the air flow in and out of when the bee is at rest?
Most of the air flows in and out of the spiracles on T2 when the bee is at rest.
How does the oxygen intake change when the bee is flying?
When flying, the bee needs much more oxygen; air is drawn in through the spiracles on T2 and abdominal segments, and pushed out through the larger spiracles on A1.
What role do the valves at the entrances to the spiracles play during flight?
The valves at the entrances to the spiracles must coordinate during the process of respiration when the bee is flying, and they are controlled by muscles.
