3.1.1. Exchange Surfaces

What supports the structure of the gills?

The bony gill arch

Each gill filament is covered with what?

Lamellae

How do the lamellae increase the diffusion of gas exchange ?

• Large surface area

• Thin layers (so short diffusion distance)

• Have a good blood supply (so maintains the concentration gradient).

In what direction does water flow through the gill filament?

From the inside to outside.

What flows through the capillaries in the lamella?

Blood

The water and blood flow in opposite directions in the lamellae, what is this known as?

Counter-current mechanism

What does a counter-current system ensure?

There is always a concentration gradient so oxygen from the water can diffuse into the blood.

It wouldn't reach an equilibrium because new water is always being encountered.

Give 3 structural features of the gills which help to maximise the diffusion rate of haemoglobin?

1) Gills have a large surface area

2) Gills are in thin layers so there is a shorter diffusion pathway

3) A rich blood supply flowing through the lamellae to maintain the concentration gradient required for diffusion.

What’s the role of the operculum?

To protect the gills and open/close during ventilation

What is the function of cartilage and where is it found in the mammalian gas exchange system?

In the trachea, bronch and alveoli - to keep the airways open and stop them from collapsing

What is the role of goblet cells and where are they found?

Trachea and bronchus- secrete mucus onto lining of trachea to trap dust and micro-organisms that have escaped nose lining.

What is the role of ciliated epithelium cells and where are they found?

trachea,bronchus,bronchioles and alveoli- the cilia beat and move along mucus in trachea, in bronchioles allows some gas exchange.

what is the function of smooth muscle and elastic fibres in alveoli?

Elastic tissues allow alveoli to stretch as air is drawn in and return to resting size helping the air to be squeezed out- elastic recoil

what is the function of smooth muscle and elastic fibres in bronchioles?

allows bronchioles to constrict and dilate, changing the amount of air reaching the lungs

what is the function of smooth muscle and elastic tissues in the bronchi and trachea?

- the smooth muscle allows the lumen to constrict, by contracting and this minimises the amount of the substances that can be breathed in.

- the elastic fibres allow the lumen to dilate after the smooth muscle has contracted and then relaxed.

What are the three main layers in large vessels?

Tunica external, tunica media, tunica intima

Material and role of tunica externa

Made of elastic and collagen fibres and used for the expansion of the vessel.

Material and role of tunica media

Made of elastic and smooth muscle tissue and allows the vessel to stretch and contract.

Material and role of tunica intima

one cell thick made of endothelium and allows for rapid diffusion

How is a continuous unidirectional flow of water maintained?

Water is forced over gill filaments by pressure differences.

Name the process which ensures there is always a diffusion gradient between the adjacent flows in the lamellae.

Counter-current mechanism

When the surface area increases what happens to rate of diffusion?

It increases

What happens to the intercostal muscles, the rib cage, the diaphragm and the lungs when we exhale?

The intercostal muscles relaxes, the rib cage goes in and down, the diaphragm relax and moves back up and then the lungs volume decrease which causes the pressure to increase, which causes air to rush out.

What happens to the intercostal muscles, the rib cage, the diaphragm and the lungs when we inhale?

The intercostal muscles contract, the rib cage goes out and up, the diaphragm contracts and flattens and then the lungs volume increases which causes the pressure to decrease, which causes air to rush in.

Give the route of insect gas exchange

Spiracle > Tracheal tubes > Tracheoles > Muscle Fibres

what does air enter and leave through in insects?

Spiracles

How is gas exchange controlled in insects?

By the opening and closing of spiracles

What’s a problem of gas exchange in insects

Water loss

what is the name of the liquid at then end of the tracheoles?

Tracheal fluid

Why is water loss a major drawback of breathing air?

The combination of of large surface areas and moist membranes means that air that is exhaled is saturated with water vapour