Organisms exchange systems within their environment Flashcards
Smaller organisms SA:V ratio
Larger surface area to volume ratio
Larger organisms SA:V ratio
Smaller surface area to volume ratio
Fish gill structure
Made up of gill filaments attached to gill arch stacked up in a pile. Right angled to filaments are gill lamellae increasing SA.
Counter current flow
Blood flowing through lamellae in the gills, flows in one direction
water flows over fish in opposite direction
- water always has a higher concentration of oxygen than the blood (creates steep concentration gradient)
Adaptations of lamallae
Lots of blood capillaries increasing blood supply
Thin layer of cells creating a short diffusion pathway
Limiting water loss in insects
- Small SA:V ratio
- Waterproof coverings (exoskeleton/waxy cuticle)
- Spiracles use muscles to close if dehydrated
- Tiny hairs surround spiracles to retain water and decrease water potential, decreasing diffusion rate
Limiting water loss in plants
- Waxy cuticle
What are xerophytes?
Plants which are adapted to living in areas where water is in deficit (cacti).
Adaptation of xerophytes
Thick cuticle, rolling up leaves, hairy leaves, stomata in pits or grooves, reduced SA:V ratio
Inspiration
- External intercostal muscles contract causing ribs to move up and out
- Diaphragm contract and so moves down and flattens increasing the volume of the thoracic cavity
- Atmospheric pressure is greater than in lungs and so air is rushed in the lungs
Expiration
- External intercostal muscles relax causing ribs to move down and in
- Diaphragm relax and so moves up and becomes dome-shaped decreasing the volume of the thoracic cavity
- Atmospheric pressure is smaller than in lungs and so air is rushed out the lungs
Digestive system function
Digests and processes food
Parts of digestive system
Oesophagus, stomach, ileum, large and small intestine, rectum, salivary glands, pancreas
Physical breakdown of digestion
The breaking down of food into smaller pieces by structures (makes it possibe to ingest, provides a large SA for chemical digestion)
- Teeth
- Muscles in the stomach wall
Chemical breakdown of digestion
Hydrolysis of large, insoluble molcules into smaller soluble ones.
- Enzymes
Carbohydrase (digestive enzyme)
Hydrolyses carbohydrates into monosaccharides.
Amylase (produced in mouth and pancreas)
- hydrolyses glycosidic bonds of starch into maltose in salivary glands and pancreas
Maltase (produced by lining of ileum)
- hydrolyses maltose from starch breakdown into a-glucose
Lipase (digestive enzyme)
Hydrolyse lipids into glycerols and fatty acids.
Lipase (produced in pancreas)
- hydrolyses ester bonds to fatty acids and monoglycerides in the small intestine
What is emulsification?
The process by which lipids are split into tiny droplets micelles by bile salts (produced in liver).
- increases SA of lipids to speed up action of lipase
Protease (digestive enzyme)
(produced in stomach) Hydrolyse proteins to amino acids.
Endopeptidase- hydrolyse peptide bonds within polypeptide chains to produce dipeptides
Exopeptidase- hydrolyse peptide bonds at the ends of polypeptide chains to produce dipeptides
Dipeptidase- hydrolyse dipeptides into amino acids which are released into the cytoplasm of the cell
Structure of the ileum
- Functioned to absorb the products of digestion
Wall is folded and possesses finger- like projections known as villi situated between lumen and the blood and tissues of body.
What are the adaptations of the villi?
- Large quantity increasing SA
- Very thin creating short diffusion pathway
- Contain muscle to move maintaining diffusion gradients
- Good blood supply maintaining diffusion gradient
- Epithelial cells have microvilli further increasing SA
Absorption of amino acids and monosaccharides
Absorption of triglycerides
The role of haemoglobin
To load, transport and unload oxygen
What is haemoglobin?
Haemoglobin is a protein with a quaternary structure.
Structure of the human heart
Veins- vena cava (deoxygenated), pulmonary vein (oxygenated)
Arteries- aorta (oxygenated), pulmonary artery (deoxygenated)
Right atrium and left atrium
Right ventricle and left ventricle
What is the function of valves?
To prevent the backflow of blood and maintain an unidirectional flow
What are the two valves?
Atrioventricular valves
Semi- lunar valves
How is the heart supplied with oxygen?
Coronary arteries which branch off aorta
Blockage of these can cause myocardial infarction (heart attack)
Cardiac output
Volume of blood pumped by one ventricle of the heart in one minute
Cardiac output = heart rate x stroke volume
Heart rate
The rate at which the heart beats
Stroke volume
Volume of blood pumped out at each beat
Arteries
Carry blood away from the heart and into arterioles
Artery structure
- Thick muscular wall
- Narrow lumen
- Thick elastic layer
- No valves
- High pressure
Arterioles structure
-Thicker muscular wall than arteries to narrow lumen and restrict blood flow into capillaries
-Thinner elastic tissue than arteries and pressure is lower
Vein structure
- Thin muscular wall
- Thin elastic layer
- Valves
- Low pressure
- Wide lumen
Capillary structure
- One cell thick creating short diffusion pathway
- Narrow lumen reducing diffusion pathway
- Large quantity increasing SA
- Highly branched providing SA
- Spaces between lining of endothelial cells so white blood cells can escape to deal wuth infections
Capillaries
Exchange metabolic materials such as O and CO2 between blood and cells of body
Veins
Carry blood to heart
Tissue fluid
Watery liquid containing glucose, amino acids, fatty acids, ions in solution and oxygen. Supplying tissues with these substances, receiving carbon dioxide and other waste products from tissues
Formation of tissue fluid
How does air move in the insects?
Moves in the insect via the spiracles in the outer surface, this occurs by rhythmic abdominal movements.
Air then moves into the tracheae to the tracheoles and to cells.
Structure of insect
Spiracles- tiny holes on outer surface able to let air in and out and control water loss (use specialised muscles to control this)
Trachea- microscope air filled pipes, lined with chitin
Tracheoles- smaller tubes branched off trachea which deliver oxygen to cells and tissues
Mammalian lungs
- Supported and protected by rib cage
- Trachea is a flexible airway covered in cartilage (walls lined with cilliated epithelium and goblet cells) which leads to lungs
- Bronchi are two divisions of trachea, one leading to each lung
- Made up of a series of branched tubules, branchioles which formed air sacs alveoli
- Alveoli are lined with epithelium and have elastic fibres to return to normal shape after breathing
Increasing rate of diffusion in humans
- Alveoli have large quantity in lungs producing large SA
- Walls are one cell thick of flat cells forming short diffusion pathway
- Surrounded by network of capillaries creating good blood supply and increase SA
Lung volume
Spirometer used to measure lung volume and diagnose lung diseases.
- A chamber filled with oxygen moving up and down with each breath
Functions of spirometer
Person breathes O out of chamber and CO2 into chamber (dangerous amount exhaled, soda lime used to absorb)
Attached to lid is a pen which records movements on rotating drum to produce spirometer trace
Tidal volume
Volume of air in each breath
Forced Expiratory Volume (FEV)
Maximum volume of air that can be breathed out in one second
Forced Vital Capacity (FVC)
Maximum volume of air that can be breathed out forcefully after a deep breath in
Residual volume
Volume of air that always remains in lungs even after forced expiration
Total lung capacity
Maximum volume of air that can be inhaled into lungs
Ventilation rate
Number of breaths per minute
Which side of the heart is thicker?
Left side is thicker as it is responsible for pumping blood to the rest of the body (contracts more powerfully)
Septum
Separates the two sides of the heart
- Interatrial septum (separates atria)
- Intraventricular septum (separates ventricle)
Factors affecting activity of enzyme
Enzyme concentration
Substrate concentration
pH
Temperature
What happens to enzymes on very high temperatures?
The rate of reaction is increased with the increase of temperature but up to a certain limit. If the temperature is increased further, the enzyme is denatured.
How does pH affect the activity of enzymes?
Every enzyme works efficiently on optimum pH. A change in the optimum pH results in the denaturation of the enzyme.
Xylem functions
