ZOO502 Quiz by Sir Arslan

ZOO-502 Addition 2 (7 September 2021) · CURRENT PAPER FILE (2021) · Admire group of zoologist · How to prevent alveoli expansion? 2

Alveoli are very small bubble-like structures that are inflated and deflated alternately.

The continuous inflation and deflation creates mechanical problems that might cause them to collapse. The air pressure inside the alveoli with thin walls may cause them to burst or join with other larger alveoli with lower pressure, forming larger sacs. This is known as alveolar collapse. It results in reduced surface area available for gas exchange.

Prevention of Alveolar Collapse

Alveolar collapse normally does not occur in the lung for two reasons: • surrounding tissue helps prevent overexpansion of alveoli • presence of pulmonary surfactants Role of Pulmonary Surfactants in Preventing Collapse Due to presence of surfactant on the surface of alveoli, the wall tension increases when the surface film is expanded and decreases when it is compressed. When their volume decreases (deflation), alveoli fold and the layer of surfactant between the folds becomes thick. Thick layer of surfactant reduces the surface tension. This permits easy inflation of folded alveoli. This effect of surfactants also minimizes pressure differences between large and small alveoli, thus reducing the chance of collapse.

1. Baroreceptors? 2

Baroreceptors

The baroreceptor system is a simple and rapidly acting control mechanism that contributes to the regulation of arterial blood pressure.

Baroreceptors in Vertebrates

Baroreceptors are widely distributed in the arterial system of vertebrates.

• The central cardiovascular system of amphibia, reptiles and mammals has unmyelinated baroreceptors.
• These unmyelinated baroreceptors only respond to pressures above normal, initiating reflexes that reduce arterial blood pressure and thus protect the animal from damaging increases in blood pressure
• Mammals also have myelinated baroreceptors which respond to blood pressures below normal, thus protecting the animal from prolonged periods of reduced blood pressure.
• The myelinated baroreceptors are present in the mammalian carotid sinus, aortic arch, subclavian artery, pulmonary arteries and the wall of right atrium

2. What is hypoxia? How it effects aquatic animals? 3

Hypoxia is a condition in which the body or a region of the body is deprived of adequate oxygen supply.

Respiratory Responses of Aquatic Animals to Hypoxia

Oxygen level in aquatic environment varies frequently. Aquatic animals are subjected to more frequent and rapid changes in oxygen levels. Many aquatic animals can withstand very long periods of hypoxia. Many of these animals utilize a variety of anaerobic metabolic pathways to survive the period of reduced oxygen availability. Many animals adjust the respiratory and cardiovascular systems to maintain oxygen delivery during reduced oxygen availability. For example, many fishes increase gill ventilation rate in hypoxic conditions. Ram ventilators (e.g. tuna) swim forward with their mouth open, increase the size of gap during hypoxia to increase water flow over the gills.

3. Physiological adoptaion of ectotherms in hot environment? 3

Strategies to Live in Hot Environments

Most ectotherms actively respond to prevent elevation of their body temperatures to the critical thermal maximum. They tend to eliminate excess heat gained from the environmental by behavioral and physiological mechanisms.

Physiological Adaptations

Most ectotherms have high heat conductance that allows them to radiate heat rapidly on moving to less warm places. Above 40oC many reptiles start panting, just like birds and mammals to increase heat loss through respiratory evaporation that causes cooling. The marine iguanas can regulate heart rate and flow of blood to the surface tissues to either absorb or eliminate heat. The Gila monster (Heloderma suspectum) evaporates water from its cloaca to cool its internal body temperature—a process similar to sweating in mammals.

Q4. Role of nervous system in maintaining blood pressure?

Neural Mechanisms

Neural mechanisms respond to changes in arterial pressure or blood gas levels sensed at specific sites. When those changes occur, the cardiovascular centers in the medulla oblongata and pons adjust cardiac output and peripheral resistance to maintain blood pressure and ensure adequate blood flow.

Q5. Alimentary canal?

The alimentary canal of all animals has a basic tubular organization that extends between two openings, a mouth and an anus.

Mammalian Digestive Tract

The mammalian digestive tract is a representative example of an alimentary canal.

Q6. Objectives of ethology?

Ethology

The scientific study of animal behavior in their natural environment is called as ethology

Objectives of Ethology

1. Understanding the stimuli that elicit behavior.
2. Understanding the physiological mechanisms that mediate the response.
3. Understanding how an animal's experience during growth and development influence the response.
4. Understanding how the behavior aids in survival and reproduction.
5. Understanding the behavior's evolutionary history