Specialised exchange surfaces

Question 1

Lungs

Inhalation process

5 steps

Answer 1

1. Diaphram contracts (moves down)
2. External intercostals contract, Internal intercostals relax.
3. Thoracic volume increases
4. Thoracic pressure decreases
5. Air flow moves into the lungs

Question 2

Lungs

Exhalation process

5 steps

Answer 2

1. Diaphram relaxes (moves up)
2. External intercostals relax and internal intercostals contract (rib cage moves down and in)
3. Thoracic volume decreases
4. Thoracic pressure increases
5. Air flow moves out of lungs

Question 3

Lungs

Breathing rate

Define

Answer 3

Number of inhalations/exhalations completed in one minute

Question 4

Lungs

Tidal volume

Define

Answer 4

Volume of air per breath

Question 5

Lungs

Pulmonary ventilation rate (PVR)

Definition and measurement

Answer 5

Total volume of air moved into and out of the lungs per minute. Measured in L/min

Question 6

Lungs

Equation for PVR

Answer 6

PVR= TV X BR

Question 7

Lungs

Oxygen uptake

Definition

Answer 7

Rate at which oxygen is absorbed into the bloodstream from the alveoli and delivered to the tissues for cellular respiration.
Closely related to PVR.
Measured in mL/min

Question 8

Lungs

1L= ?dm3 = ?cm3

Answer 8

1L = 1dm3 = 1000cm3

Question 9

What do lung surfactants do?

Answer 9

• Maintain structure of the alveoli
• Phospholipid substance, coats surface of alveoli
• Without it, the watery lining would create surface tension and the alveoli would collapse

Question 10

Nasal cavity

Answer 10

• Large SA:V ratio
• Good blood supply-warms air into body
• Hairy lining-traps dust and bacteria

Question 11

Trachea

Answer 11

• Tubular structure supported by layer of cartilage that prevents it from collapsing
• Rings are incomplete to allow it to bend for swallowing food in the oesphagus behind
• Lined with ciliated epithelial and goblet cells preventing dust and bacteria from entering

Question 12

Bronchi

Answer 12

• Extensions of trachea
• Cartilage rings hold it open

Question 13

Bronchioles

Answer 13

• No cartilage- held open by smooth muscle
• When muscle contracts, the bronchioles contract
• Linked with thin layer of epithelial tissues making same gas exhange possible

Question 14

Alveoli

Answer 14

• Large SA:V ratio
• 200um-300um diameter
• Made of epithelial tissue, collagen and elastic fibres
• 1 cell thick
• Good blood supply

Question 15

Respiration

Answer 15

A process that occurs in cells which energy is released

Question 16

Breathing

Answer 16

Movement of respiratory muscles that make the lungs expand and contract, so air can be taken in/out

Question 17

Ventilation

Answer 17

Mass flow of gases moving in/out of the thoracic cavity ensuring a steep conc. gradient

Question 18

Why does the volume in the spirometer decreasing with time

Answer 18

Because we don’t expire as much oxygen compared to when we inspire, so oxygen is being subtracted from the chamber

Question 19

Adaptations of gills for efficient gas exhange

Answer 19

• Large SA provided by lamellae
• Lamellae membranes are thin
• Good blood supply to maintain steep diffusion gradient
• Counter current flow of blood and water creates steep conc. gradient

Question 20

Exoskeleton of terrestrial insects

Answer 20

• Made of hard fibrous chitin for protection
• Chitin is a polysaccharide made up by modified glucose

Question 21

Why do large multi-cellular organisms have developed specialised exchange surfaces

Answer 21

• High metabolic demands
• Need to regulate internal conditions (homeostasis)
• Require high volumes of substances quickly
• Produce high volumes of waste need to be removed

Question 22

Components of circulatory systems

Answer 22

• A fluid in which substances are transported
• Vessels through which the fluid can flow
• A pumping mechanism to move the fluid

Question 23

Open circulatory system

Answer 23

• Has a heart that contracts and pumps a fluid called haemolymph through short vessels into a large cavity called haemocoel
• When the heart relaxes, the haemolymph is sucked back in via small valve-like openings called ostia located in the hearts muscular walls

Question 24

Closed circulatory system

Answer 24

• Blood is fully enclosed within blood vessels at all times
• From the heart, blood is pumped through progressively smaller blood vessels

Question 25

# Types of capillaries Continuous

Answer 25

Endothelial cells are tightly closed to each other. Substances cannot move out of these gaps Found in fat, muscle, nervous system

Question 26

# Types of capillaries Fenestrated

Answer 26

Endothelial cells have little perforations and substances can move through these provided theyre small. Found in intestrial villi, endocrine glands

Question 27

# Types of capillaries Discontinuous

Answer 27

Endotheolial cells are not very tightly closed together and substances can move through

Question 29

# Composition of blood Plasma

Answer 29

* 55% of blood * A yellow liquid which contains oxygen, AA, mineral ions, fats, hormones, anitbodies etc.

Question 30

# Composition of blood Erythrocytes, leukocytes, platelets

Answer 30

45% of blood

Question 31

Functions of the blood

Answer 31

* Transport of oxygen, CO2, digested food, nitrogenous waste, hormones, platelets, cells and antibodies * Maintains body temp * Acts as a pH buffer-maintains pH of blood to 7.35-7.45

Question 32

Hydrostatic pressure

Answer 32

Pressure of the blood from heart contractions, forces fluid out capillaries

Question 33

Oncotic pressure

Answer 33

Pressure that tissue fluid forces water to move into the capillaries by osmosis

Question 34

Adaptations pof erythrocytes to maximise transport of 02

Answer 34

* No nucleus or organelles to maximise space for Hb * Formed from multipotent STEM cells in the bone marrow * Flattened, biconcave disc shape to ensure large SA:V ratio for efficient gas exchange

Question 35

Adaptations of Hb to maximise transport of 02

Answer 35

* High oxygen binding affinity-efficiently binds to 02 in the lungs * Positive cooperative binding- as one 02 molecule binds to one subunit, it increases the affinity of the remaining subunits for 02, enhancing overall 02 uptake and release * Reversible binding- Hb can readily bind and release 02 molecules in response to changes in 02 conc, ensuring efficient delivery to tissues

Question 36

Oxygen dissociation curve

Answer 36

* At low pp02, its hard for Hb to bind to 02 because the 4 polypeptide chains are close together * As pp02 increases, and once the first 02 is binded, the Hb structure relaxes and changes shape, so the last 3 02 are loaded easier

Question 37

Bohr shift

Answer 37

Occurs when a high ppC02 causes Hb to release oxygen into respiring tissues. Describes the effect of high C02 conc. on Hb's affinity of oxygen

Question 38

Transport of C02

Answer 38

* 5% disolved in plasma * 20% combined with amino groups in the polypeptide chains of Hb to form carbaminohaemoglobin * 75% converted into hydrogen carbonate ions in the cytoplasm of RBC

Question 39

# Plants Herbaceous plants

Answer 39

* Do not have hard, woody stems * Their upper parts do not survive winter above ground * E.g. lavender

Question 40

# Plants Woody plants

Answer 40

* Have hard, woody stems * Survive all year * E.g. Oak trees