Transport In Animals Flashcards
Path of air in mammals
Trachea - bronchi - bronchioles - alveoli
Alveoli adaptions
Large surface area provided by shape
Fluid lining allows gases to diffuse
Two cell layers thick - (endothelial capillary, epithelial alveolar )
Inspiration
- External intercostal muscles contact
Pulls ribcage up and out - diaphragm muscles contract
Pulls diaphragm down flat - volume of thoracic cavity increases
- pressure decreases below atmospheric in lungs
- air drawn in
Expiration
- External intercostal muscles relax
Ribcage pulled down and in - diaphragm muscles relax
Diaphragm returns to dome shape - volume of thoracic cavity decreases
- pressure increases above atmospheric
- elastic recoil forces air out
Path of air in insects
Trachea - tracheoles - cells
Adaptations for gas exchange in fish
Large surface area - provided by lots of gill filaments covered in lamellae
Short diffusion pathway - 2 cells thick endothelial capillary and epithelial lamellae
Countercurrent system - blood and water flow in opposite directions ensures blood meets water with a higher concentration of oxygen to concentration gradient is established along the entire lamellae
Effect of CO2 on insects
CO2 levels rise due to respiration
Spiracles open wider
Increase rate of diffusion
During rest spiracles close to reduce water loss via evaporation
Increased activity in insects
Leads to build up of lactic acid in cells from anaerobic respiration
Lowers water potential of cells
Water in tracheoles moves into cells by osmosis
Enables more air into tracheoles increasing rate of oxygen diffusion
Where is endopeptidase found
The stomach
Where does exopeptidase come from
The pancreas
Endopeptidase function
Hydrolyses internal peptide bonds between amino acids
Exopeptidase function
Hydrolyses peptide bonds at either end of a polypeptide
Dipeptidase function
Hydrolyses dipeptides into two single amino acids
Where is dipeptidase found
Microvilli of epithelial cells in the ileum
Adaptations of ileum
Large surface area - long in length contains many villi and microvilli
High diffusion gradient - villi contain capillaries absorb monosaccharides, lacteals absorb digested lipids
Short diffusion pathway - each villi is one epithelial cell thick
Lots of mitochondria - ATP for active transport
Carrier and channel proteins - for absorption of specific molecules
Absorption of lipids
- Bile salts emulsify lipid droplets
- Bile salts, fatty acids, and monoglycerides combine and form micelles
- Micelles break down next to epithelial cell releasing fatty acids and monoglycerides
- Fatty acids, monoglycerides and glycerol recombine in smooth endoplasmic reticulum
- triglyceride is formed and packaged in the Golgi body
- Forms Chylomicrons which are absorbed into lacteals
Co transport (glucose)
- Na+ is actively transported out of the epithelial cell, concentration gradient is established
- Na+ can now diffuse in to the epithelial cell from the lumen of intestine
- glucose moves with them through carrier proteins
- glucose moves out the cell to the capillary by facilitated diffusion
Path of blood
Body - vena cava - right atrium - right ventricle - pulmonary artery - lungs - pulmonary vein - left atrium - left ventricle - aorta - body
What happens when the atrium contracts
- Volume decreases and blood pressure increases
- Ventricle relaxed blood pressure is low
- pressure gradient from atria to ventricles
- forces atrioventricular valve open
- blood moves from atria to ventricle
What happens when the ventricle contracts
- volume decreases and blood pressure increases
- atrioventricular valve forced closed preventing backflow of blood into the atria
- blood pressure in ventricles greater than in arteries
- semi lunar valve forced open
- blood flows from ventricles to arteries
Cardiac output
Stroke volume x heart rate
Arteriole capillary end
High hydrostatic pressure due to heart contraction
Hydrostatic pressure greater than osmotic pressure
Fluid and small molecules forced out
Forms tissue fluid
Large molecules remain in capillary lowering water potential
Water moves in via osmosis
Venous capillary end
Low Hydrostatic pressure due to frictional resistance
Osmotic pressure is greater than hydrostatic pressure
Water from tissues fluid reabsorbed
Haemoglobin
4 haem units
Each unit combines with one Oxygen
High affinity for oxygen at high partial pressure in lungs - O2 loaded
In tissues low partial pressure affinity decreases - O2 unloaded
Explain the S shape of the dissociation curve
One molecule of oxygen binds to 1 of 4 haem units
Causes change in tertiary structure of other haem units
Increases their affinity for Oxygen
Allows second oxygen to bind more easily
Xerophyte adaptations
- Thick cuticle
Long diffusion pathway reduces rate of evaporation - Hairs
Trap still air reducing water potential gradient - SA:V
Reduces surface area for water loss - Stomata
Reduce exposure to air currents, traps air reducing water potential gradient - Rolled leaves
Trap layers of still air reducing water potential gradient
Xylem structure
Dead tissue - no cell content
Hollow tubes - minimal resistance to flow of water and ions
Cell wall strengthened by lignin - provides support and rigidity
Transpiration stream - transports water and ions from roots to leaves
Cohesion Tension
- Solar heat energy causes evaporation of water from leaves
- Water moves from cell to cell across the leaf via osmosis
- Water drawn from xylem causing tension
- water column maintained by cohesive (attraction of water molecules to each other) and adhesive (attraction of water to xylem) forces
- Upward movement of water maintains water potential gradient
Transport in phloem
Sucrose actively transported into sieve tube by companion cell
Water potential un sieve decreases
Water from xylem moves un via osmosis
High hydrostatic pressure un sieve
In sink - sugar used for respiration
Sucrose transported from sieve to sink
Water potential in sieve increases
Hydrostatic pressure in sink decreases
