Gas exchange (copy)

Describe body heat regulation in small animals

Have a large surface area to volume ratio increases rate of respiration increases because they loose a lot of heat per gram of body tissue and have to make up for heat loss

Describe body heat regulation in large animals

Have a small surface area to volume ratio decrease their rate of respiration decreases because they do not loose a lot of heat per gram of body tissue and have a lot of cells

Describe the route of oxygen

• Mouth/nose

• Trachea

• Bronchi

• Bronchioles

• Alveoli

• Caplillaries+red blood cells

Describe how the bronchus is adapted for its function

Contains rings of cartilage to hold bronchi open

Describe how the bronchioles are adapted for its function

Contains smooth muscle that contract and relaxes to control air movement to the alveoli

How does air move into the lung

Air moves into the lung due to the differences in pressure-moves down a pressure gradient

How does oxygen move into the blood

Oxygen mines from the alveolus to the caplillaries by diffusion down the concentration gradient

Explain how oxygen diffuses into the bloodstream

• Oxygen has to diffuse across the squamous/flattened alveolar epithelium and the squamous capillary endothelium before it can reach the red blood cells and bind with haemoglobin

Explain how the lung is adapted for efficient gas exchange (6)

Concentration gradient:

• Ventilation brings in oxygen rich air and removes oxygen deficient air so there i always a higher concentration of oxygen in the alveoli compared to the blood in the capillaries

Diffusion pathway:

• Caplillaries are narrow so red blood cells move in single file which allows more time for diffusion

• Alveolar epithelium and capillary endothelium are squamous,the red blood cells are close to the capillary cell wall so there is a short diffusion distance and increased diffusion

• Thin walls

Surface area:

• Many alveoli to increase the SA for diffusion

• Alveoli walls are folded

• Many capillaries

• Providing large SA to volume ratio

Describe the process of inhalation

• External intercostal muscles contract

• The ribs move up

• The diaphragm contracts and flattens

• Volume of thoracic cavity increases

• Pressure decreases so the pressure in the lungs is lower than the atmosphere

• So air moves into the lungs down the pressure gradient

Describe the process of exhalation

• Both internal and external intercostal muscles are relaxed

• There is alveolar recoil which causes the ribs to move down

• The diaphragm relaxes

• Volume in thoracic cavity decreases

• Pressure increases higher than atmosphere

• Air moves out of the lungs down the pressure gradient

Describe the difference between forced exhaustion and normal

In forced exhalation internal intercostal muscles contract process is active rather than passive

What is the breathing rate

Breaths per minute

What is the tidal volume

Volume of air breathed in and out in a single breath during rest

What is the equation for pulmonary ventilation

Pulmonary ventilation (cm3 min)=tidal volume x breathing rate/ventilation rate

Describe the path of oxygen through an insects tracheal system

Oxygen enters the spiracles down a diffusion gradient

Oxygen travels along the trachea

Along the tracheoles(by diffusion gradient)+fluid in tracheoles

Oxygen diffuses from the tracheoles to respiring cells

Describe how an insects tracheal system is adapted for efficient gas exchange (7)

Surface area:

• There are many tracheoles,increase surface area for diffusion

• When fluid is absorbed ends of tracheoles are uncovered

Concentration gradient:

• Abdominal pumping forces air in,increasing concentration of o2 in tracheoles maintaining the concentration gradient

• There is a high concentration of oxygen in tracheoles which diffuse in from air,lower concentration of oxygen in cell as it is used for respiration

Diffusion pathway :

• Trachea/tracheoles made of thin protein walls so decrease diffusion pathway

• When fluid is absorbed into cells from tracheoles during excersie,oxygen can diffuse faster through air than fluid

• Tracheoles are highly branched so are close to cells

What is abdominal pumping

Relaxing and contracting muscles in the abdomen to facilitate breathing

Describe the process of inhalation in insects during abdominal pumping

Muscles in the abdomen relax

Abdomen relaxes

Volume increases

Pressure decreases

Air moves in down the pressure gradient

Describe the process of exhalation in insects during abdominal pumping

Muscles in abdomen contract

Abdomen is pulled in

Volume decreases

Pressure increases

Air moves out down pressure gradient

Why else may an insect use abdominal pumping

If there is a lower concentration of oxygen in the atmosphere

If the insect is very large

What difficulties do fish face with obtaining oxygen from water

• Oxygen is not very soluble in water so there is a significantly lower concentration of oxygen in water than air

• Water has a higher density than air so is harder right move over the respiratory surface durin

What is unidirectional flow

• Fish continuously pump water through its mouth over its gills forming a unidirectional Flow

Why do fish use unidirectional flow

Water is more dense than air so use less energy for muscle contraction to force water in and out

Counter current mechanism inky works when there is regular and unidirectional flow of water over the gills

Explain the importance of counter current flow

The blood in the capillaries is flowing in the opposite direction of the water

There is always a higher concentration of oxygen in the water compared to the blood in the capillary

Maintains a concentration gradient across the whole grill lamellae

Therefore diffusion can occur and more oxygen diffuses into the blood to be used for respiration

Explain how the gills of a fish are adapted for efficient gas exchange (6)

surface area:

• Many gill/gill lamellae with many filaments which increase surface area so there is a faster rate of diffusion

Diffusion pathway

• The capillary endothelium and lamellae epithelium are thin which provide a short diffusion pathway between blood and water for faster diffusion

Concentration gradient

• There is counter current flow so blood and water move in opposite directions so there is always a higher concentration of oxygen in the water compared to the caplillaries next to it which maintains the concentration gradient along the whole gill lamellae for faster diffusion

• Circulation replaces blood saturated with oxygen so there is always a higher concentration of water in the blood to maintain high concentration gradient