T6:Exchange DONE Flashcards
Enzyme digestion, digestion ,absorption of the products of digestion.
What features increase the rate of diffusion?
-large surface area
-short diffusion pathway
-steep concentration gradient
How do single-celled organisms absorb and release gases?
-diffusion through their cell-surface membranes
-because of large surface area, a thin surface and a short diffusion pathway
How do waxy exoskeleton help insects?
–protection
-retention of water
What system do insects use to exchange gases?
-tracheal system
Describe the tracheae in insects.
-air-filled network of tubes
-supported by strengthened rings to prevent them collapsing
-divide into smaller dead-end (tracheoles)
How does gas exchange happen in insects?
-Air moves through pores in exoskeleton called spiracles
-O2 goes down concentration gradient to cells
-tracheae branch to tracheoles (thin, permeable walls)
- O2 diffuses directly from tracheoles into respiring cells
-CO2 moves from spiracles to be released
How can contraction of muscles in insects move gasses?
-squeeze of trachea enabling mass movements of air in and out
-speeds up the exchange of respiratory gases
What three ways do gases move in and out the tracheal system?
-Along a diffusion gradient (oxygen used up in cells decreases the concentration creating a gradient)
-Mass transport (contraction of musclee can squeeze the trachea enabling mass movement of air in and out)
-End of tracheoles filled with water (at high activity cells undergo anaerobic respiration =production of lactate lowering water protection of cells so water exits tracheoles via osmosis decreasing volume of water and increasing air)
How does body size effect heat exchange of an organism?
-metabolic activity inside cells creates heat
-small SA:V means less heat is lost
-small organisms need high metabolic rate
What are the tracheal systems limitations in insects?
-relies on diffusion to exchange gases (with environment and cells)
-for effective diffusion pathway needs to be short
What are fishes specialised gas exchange surface ?
-gills
- fish have a waterproof which is gas tight
How is the structure of gills adapted for gas exchange?
-gill filaments, for large SA
-lamellae on gill filaments which have blood capillaries and single layer of epithelial cells
How and why do fish ventilate their gills?
-maintain a strong diffusion gradient
-buccal pump mechanism
What is the buccal pump mechanism?
-coordinate opening of the opercular vents and the closing of their buccal cavity( mouth)
-open their buccal cavity, and close the opercular vents to draw freshwater in which gets pumped over the gills
-buccal cavity will close and the vents will open, water that’s in the mouth can flow over the gills and out of the vent.
What is countercurrent flow in fish?
-term that describes two liquids in close proximity to each other flowing in opposite directions
- gill filaments and the lamellae ensures water passes over them is countercurrent to the flow of blood through the capillaries for steep concentration gradient
How does gas exchange happen in plants?
-No specific transport system due to short diffusion pathway
-main gas exchange surface mesophyll cells (Numerous interconnecting air-spaces so gasses come in contact)
-Diffusion takes place in the gas phase (air)
What are stomata and how do they function?
-pores in the epidermis
-Guard cells control the opening and closing of the stomata (when swollen they close, when flaccid they close)
What are xerophytes?
-plants specially adapted for life in a warm, dry or windy habitats, where water loss is a problem.
What are xerophytic adaptations?
-Stomata sunken pits to trap water vapour
-‘hairs’ on the epidermis to trap water vapour
-Curled leaves with the stomata inside, protecting them from wind
-reduced number of stomata
-Thicker waxy, waterproof cuticles evaporation
What form is energy released in human
respiration?
-ATP
Why is the volume of oxygen absorbed and volume of carbon dioxide removed large in mammals?
-relatively large organisms with a large volume of living cells
-maintain a high body temperature which is related to them having high metabolic and respiratory rates
Describe the specialised surface in mammals?
-Lungs
-spongy, air-filled organs located on either side of the chest (thorax)
What are the respiratory passages external to the lungs?
-Nasal cavities
-Nasopharynx and oropharynx
-Larynx
-Trachea
-Primary bronchi
What are the characteristic of the trachea?
- flexible airway that is supported by rings of cartilage (stops from collapsing due to air presssure)
-walls made up on muscle, lined with ciliated epithelium and goblet cells(production of mucus).
-
What are the characteristic of the bronchi?
-two divisions of the trachea, each leading to a lung
-produce mucus to trap dirt particles and cillia to move it to the throat
-supported by cartilage
What are the characteristic of the bronchioles?
- branching subdivisions of the bronchi
-walls made of muscle (control the flow of air in and out of the alveoli) lined with epithelial cells
What are the characteristic of the alveoli?
- tiny air-sacs located at the end of the bronchioles and lined with epithelium
-collagen and elastic fibres between them
lined with epithelium
-elastic fibres (allow the alveoli to stretch as they fill with air when breathing in) - alveolar membrane is the gas-exchange surface
How do gasses diffuse across to get to the blood from the alveoli?
-Gases diffuse across the alveolar epithelium and across the capillary endothelium
-then into haemoglobin in the blood
What is ventilation in the lungs?
-consists of inspiration (breathing in) and expiration (breathing out).
-controlled by movements of the diaphragm, internal and external intercostal muscles and ribcage
What happens at inspiration stage of gas exchange?
-active process
-external intercostal and diaphragm muscles contract
-ribcage moves up and out and the diaphragm flattens
-volume in the thoracic cavity increases and lung pressure decreases
- air flows down the trachea and into the lungs (down pressure gradient)
What happens at expiration stage of gas exchange?
-external intercostal and diaphragm muscles relax
-ribcage moves down and in and the diaphragm curves
-volume decreases in thoracic cavity
-air goes out the lungs down the pressure gradient
How can expiration be forced?
-external intercostal muscles relax
- Internal intercostal muscles contract
-ribcage pulled futher down
How is alveoli a specialised gas exchange surface?
-protein called elastin which help with recoil
-Thin exchange surface- the alveolar epithelium is only one cell thick
-Large surface area- there are millions of alveoli
How does oxygen moves through the gas exchange system?
-moves down the trachea, bronchi and bronchioles into the alveoli DOWN A PRESSURE GRADIENT
-then pass through two layers of cells (the alveolar epithelium and the capillary epithelium)
-into a compound called haemoglobin in the blood
