Respiration in Cockroaches
Respiration is a metabolic procedure that is performed in all living organisms. This process mainly includes the synthesis of energy, with the consumption of oxygen and the liberation of CO2 from the oxidation of complex organic substances.
The Insect Respiratory system is not like the respiratory system in humans. Animals like cows, birds, snakes, lions, elephants, including humans, have lungs as their primary breathing organ. In these animals, lungs are for exchanging air with the help of the nostrils, nasal cavity, and trachea. Insects and worms do not have lungs to perform their respiratory function. Thus, in worms and insects, breathing occurs through a different system of respiratory organs.
Cockroaches can hold their breath for as much as seven minutes. Their respiratory system is extremely effective but there are no lungs. Rather they have the following structures.
Spiracles:
10 pairs of spiracles or stigmata are present on the lateral side of the body. The largest first set is present on the mesothorax. The second pair is on the metathorax and the rest eight sets are on the first 8 abdominal segments. Each spiracle is oval fit and bounded by an annular sclerite having a filtering apparatus formed by the bristles to eliminate dust particles from the inflowing air.
The spiracles in the mesothorax have 2 lips– a rigid anterior lip and a movable posterior lip. In metathorax, the lips of the spiracles are joined ventrally. In the abdominal area, the spiracles have no lips. The thoracic spiracles open straight within the segmental trachea, but the abdominal spiracles open first within the dilated part of the trachea– the atrium, from which originate the segmental tracheae.
Tracheae:
In Cockroaches, the haemocoel includes a network of elastic, closed air tubes or tracheae. Three longitudinal tracheal trunks are present on each side of the abdominal cavity.
The dorsal and forward trunks exist near the middle line, while the lateral trunk is present on the lateral side of the abdominal cavity. Each lateral trunk is divided into two parts– the anterior part exists in between the mesothoracic, metathoracic, and the first abdominal spiracle, while the posterior part extends from the second abdominal spiracle to the 8th abdominal spiracle.
The large trachea is internally supported by a spiral ring of chitin, called taenidia or intima, which prevents the tracheal tubes from collapsing. In addition, chitinous fibrils of 10 to 30 nm thickness and an epicuticle of lipoprotein, line the lumen of the tracheae.
Tracheoles
The main tracheae divide and subdivide forming very fine thin-walled tubules called tracheoles. These tracheoles end into blind ducts partially filled with fluid, in which the oxygen dissolves. These surround the organs and the tissues and directly supply oxygen to the living cells.
Mechanism of Respiration
A concentration gradient is set up in between them and the spiracular openings and oxygen diffuses into the trachea from the outside air. The movement of the air through the tracheal trunks transfers gases through inspiration and expiration. Air is pumped in and out of the tracheae by the growth and contraction of the abdominal muscles (Dorsoventral muscles).
When the abdominal area expands, the first 4 pairs of spiracles open, and air rushes in through these spiracles into tracheoles. The abdominal area contracts, the anterior four pairs of spiracles close, and the posterior 6 pairs of spiracles open. This forces air through channels and ultimately out of the body.
In this way exhalation and inhalation take place. From the spiracles, air enters into the trachea and after that tracheole, from where gaseous exchange between tissue cells and air in the tracheole takes place. Hence air is directly supplied through tracheoles to the tissue cells. Blood is not involved in the transport of gases.
The opening helps closure of the spiracles depending upon the carbon dioxide concentration. The width of the spiracular opening increases with the increase of temperature level from 20 ° to 32 ° C. In cockroaches, blood takes no part in respiration, and the oxygen-bearing fluid of the tracheoles serves in internal respiration, like that of lymph in vertebrates. In these insects, more than 10% gaseous exchange can occur through the body surface.
MCQs for Respiration in Cockroaches
- What is the primary metabolic process that involves the synthesis of energy in living organisms?
- a) Photosynthesis
- b) Respiration
- c) Digestion
- d) Excretion
Answer: b) Respiration
- What distinguishes the insect respiratory system from that of humans?
- a) Lungs
- b) Gills
- c) Tracheae
- d) Nasal cavity
Answer: c) Tracheae
- How long can cockroaches hold their breath?
- a) 2 minutes
- b) 5 minutes
- c) 7 minutes
- d) 10 minutes
Answer: c) 7 minutes
- Where are spiracles present in cockroaches?
- a) Dorsum
- b) Ventrum
- c) Lateral side of the body
- d) Head region
Answer: c) Lateral side of the body
- What is the function of the filtering apparatus in spiracles?
- a) Oxygen absorption
- b) Removal of dust particles
- c) CO2 elimination
- d) Tracheal support
Answer: b) Removal of dust particles
- How are the spiracles in the mesothorax different from those in the metathorax?
- a) Mesothoracic spiracles have lips, metathoracic spiracles do not.
- b) Metathoracic spiracles have 2 lips, mesothoracic spiracles do not.
- c) Both have lips.
- d) Neither has lips.
Answer: a) Mesothoracic spiracles have lips, metathoracic spiracles do not.
- What prevents the tracheal tubes from collapsing in cockroaches?
- a) Cartilage rings
- b) Taenidia or intima
- c) Chitinous fibrils
- d) Lipoprotein lining
Answer: b) Taenidia or intima
- What is the purpose of tracheoles in the respiratory system of cockroaches?
- a) Oxygen storage
- b) CO2 elimination
- c) Oxygen supply to living cells
- d) Fluid transport
Answer: c) Oxygen supply to living cells
- How is the movement of air through tracheal trunks achieved during respiration?
- a) Blood circulation
- b) Muscular contraction and expansion
- c) Nervous impulses
- d) Digestive processes
Answer: b) Muscular contraction and expansion
- What is responsible for the closure of spiracles in cockroaches?
- a) Oxygen concentration
- b) Temperature
- c) Carbon dioxide concentration
- d) Blood pressure
Answer: c) Carbon dioxide concentration
- How is gaseous exchange accomplished in tracheoles?
- a) Blood vessels
- b) Capillaries
- c) Blind ducts partially filled with fluid
- d) Lungs
Answer: c) Blind ducts partially filled with fluid
- What initiates the pumping of air in and out of tracheae during respiration in cockroaches?
- a) Brain signals
- b) Heartbeat
- c) Abdominal muscles
- d) Spiracles opening and closing
Answer: c) Abdominal muscles
- What happens during the expansion of the cockroach’s abdomen in respiration?
- a) Spiracles open, and air rushes in
- b) Spiracles close, and air is expelled
- c) Both spiracles opening and closing
- d) No change in spiracles
Answer: a) Spiracles open, and air rushes in
- Which part of the cockroach’s respiratory system is involved in the direct supply of air to tissue cells?
- a) Trachea
- b) Spiracles
- c) Tracheoles
- d) Taenidia
Answer: c) Tracheoles
- How much gaseous exchange can occur through the body surface in cockroaches?
- a) Less than 5%
- b) Approximately 5%
- c) More than 10%
- d) None
Answer: c) More than 10%
- In cockroaches, what serves in internal respiration instead of blood?
- a) Hemoglobin
- b) Oxygen-bearing fluid in tracheoles
- c) Lymph
- d) Plasma
Answer: b) Oxygen-bearing fluid in tracheoles
- What is the primary role of the spiracular opening in cockroach respiration?
- a) Oxygen intake
- b) CO2 elimination
- c) Closure depending on temperature
- d) Blood circulation
Answer: b) CO2 elimination
- How does the width of spiracular opening change with an increase in temperature in cockroaches?
- a) Decreases
- b) Remains constant
- c) Increases
- d) No effect
Answer: c) Increases
- What is the purpose of the epicuticle in the tracheae of cockroaches?
- a) Structural support
- b) Oxygen transport
- c) Fluid lining
- d) Protecting the lumen
Answer: d) Protecting the lumen
- What triggers the movement of air through the tracheal trunks in cockroach respiration?
- a) Digestive processes
- b) Inspiratory impulses
- c) Temperature changes
- d) Contractions and expansions of abdominal muscles
Answer: d) Contractions and expansions of abdominal muscles
- How does the abdominal contraction affect spiracles in cockroaches?
- a) First 4 pairs open, next 6 pairs close
- b) All pairs open simultaneously
- c) First 4 pairs close, next 6 pairs open
- d) No effect on spiracles
Answer: c) First 4 pairs close, next 6 pairs open
FAQs – Respiration in Cockroaches
- What is respiration in living organisms?
- Respiration is a metabolic process involving the synthesis of energy, consumption of oxygen, and liberation of CO2 from the oxidation of complex organic substances.
- How does the insect respiratory system differ from that of humans?
- Unlike humans with lungs, insects and worms utilize a different system of respiratory organs for breathing.
- How long can cockroaches hold their breath?
- Cockroaches can hold their breath for up to seven minutes.
- What structures replace lungs in the respiratory system of cockroaches?
- Cockroaches lack lungs; instead, they have structures called spiracles, tracheae, and tracheoles.
- What is the function of spiracles in cockroaches?
- Spiracles are openings present on the lateral side of the body that allow the inflow of air. They are equipped with a filtering apparatus to eliminate dust particles.
- How are spiracles different in the mesothorax and metathorax of cockroaches?
- Spiracles in the mesothorax have two lips, while those in the metathorax have a joined ventral lip. Abdominal spiracles lack lips.
- What supports the tracheal tubes in cockroaches and prevents them from collapsing?
- The tracheal tubes in cockroaches are supported by a spiral ring of chitin called taenidia or intima.
- What are tracheoles, and what is their role in respiration?
- Tracheoles are thin-walled tubules branching from tracheae. They end in blind ducts filled with fluid, facilitating gaseous exchange and supplying oxygen directly to living cells.
- How is the movement of air achieved in the tracheal trunks during cockroach respiration?
- Muscular contraction and expansion of abdominal muscles (Dorsoventral muscles) pump air in and out of the tracheae.
- Describe the process of exhalation and inhalation in cockroaches.
- During abdominal expansion, the first four pairs of spiracles open, allowing air to rush into tracheoles. During abdominal contraction, the anterior four pairs of spiracles close, and the posterior six pairs open, forcing air out of the body.
- Is blood involved in cockroach respiration?
- No, blood plays no part in cockroach respiration. Gaseous exchange occurs through the oxygen-bearing fluid of the tracheoles.
- What determines the opening and closure of spiracles in cockroaches?
- The closure of spiracles depends on the carbon dioxide concentration. The width of spiracular openings increases with a rise in temperature from 20°C to 32°C.
- How much gaseous exchange occurs through the body surface in cockroaches?
- More than 10% of gaseous exchange can occur through the body surface in cockroaches.
Summary – Respiration in Cockroaches
Respiration in cockroaches is a vital metabolic process shared by all living organisms. Unlike animals with lungs, such as humans and mammals, cockroaches have evolved a distinct respiratory system. They lack lungs but employ specialized structures, including spiracles, tracheae, and tracheoles, to facilitate efficient respiration.
Key Respiratory Structures:
- Spiracles: 10 pairs of spiracles are distributed along the lateral side of the body. They serve as openings for air intake, equipped with a filtering apparatus to eliminate dust particles. Spiracles vary in structure across the mesothorax, metathorax, and abdominal segments.
- Tracheae: The haemocoel contains a network of elastic, closed air tubes or tracheae. Three longitudinal tracheal trunks on each side of the abdominal cavity distribute air. Internally supported by chitinous rings, tracheae prevent collapse and ensure structural integrity.
- Tracheoles: Fine, thin-walled tubules, tracheoles, branch from the main tracheae. These tubules end in blind ducts filled with fluid, facilitating direct oxygen supply to organs and tissues, promoting effective gaseous exchange.
Mechanism of Respiration:
- A concentration gradient between spiracular openings and the trachea allows oxygen to diffuse into the respiratory system from the outside air.
- The movement of air through tracheal trunks, driven by the growth and contraction of abdominal muscles (Dorsoventral muscles), facilitates inspiration and expiration.
- During expansion, the first 4 pairs of spiracles open, allowing air into tracheoles. Contraction leads to closure of anterior spiracles and opening of posterior spiracles, expelling air from the body.
Unique Features of Cockroach Respiration:
- Cockroaches can hold their breath for up to seven minutes.
- Blood plays no role in respiration; instead, oxygen-bearing fluid in the tracheoles supports internal respiration.
- Spiracular opening and closure are influenced by carbon dioxide concentration, with the width increasing at higher temperatures.
In conclusion, the respiratory adaptation of cockroaches showcases remarkable efficiency, allowing for sustained life without lungs. The evolutionary development of specialized structures enables these insects to thrive in various environments.