Easter Flashcards
What is positive and negative allometry?
Positive slope> expected
Negative slope < expected
What is the force of a muscle proportional to?
It’s cross sectional area
Does flight show negative or positive allometry and how?
Negative allometry
As muscles for flight increase in size so does the weight, and so harder for flight to be achieved
What are the uses of scaling relationships?
Drug dosage for people of different sizes
Determine flight and physiology of animals (extinct dinosaurs also)
Scale cardiac output
What are the effects of being a larger organism?
Small SA: Vol
Lower metabolic rate
Lower reproduction rate
More prone to extinction
Feed lower down in the food chain, where food is more abundant
What is the principle of continuity and how is it applied in the body?
Volume rate of fluid going into vessel is the same as the rate coming out of the vessel
Applied to vessels in the body
Rate dependent on velocity and area, total capillary area increases so velocity decreases, allowing for diffusion
How does Laplace’s law apply to the body?
Laplace’s law- shows relationship between pressure difference and tension on vessels
Tension is higher if radius increases, which is why for small capillaries tension is lower and no rupturing occurs
What are the main effects of gravity on the movement of blood?
Blood pooling at the bottom (legs)
Moving blood up against gravity
Maintaining constant blood pressure
How do giraffes overcome the problems of blood movement caused by gravity?
1) Stop pooling by having thick skin around legs to increase pressure, and contraction of muscles
2) Moving blood up, by creating a higher pressure in the heart to send blood to the head
3) Maintain constant BP, by having baro-reflexes that detect changes and control the cardiac output and HR, when bending down to drink
How are snakes adapted for different environments?
Arboreal- capable of managing changes in BP, heart is closer to head, thinner bodies to maintain high BP
Aquatic- larger, unable to manage changes in BP
How is water moved up the xylem?
Cohesion- tension, water molecules form bonds with each other and pull each other up
Negative pressure is created at the leaves by transpiration of water
How are xylem vessels and tracheids adapted for water transport?
Lignified walls maintaining pressure
Bordered pits, allowing flow of water between plant cells, which can be blocked off by TORUS, e.g. stop embolism spreading
What are the advantages and disadvantages of having a compound eye?
Adv
-Wide field of view
-Very sensitive to motion, as there are many ommatidia
- Fast acclimation to bright light- individually react
- High temporal resolution- due to great density of ommatidia
Disadv
-Lower spatial resolution- each ommatidia provide lower spatial acuity
-Reduced depth perception
- Inability to focus- each ommatidia has a fixed focal length
What are the advantages and disadvantages of a single lens eye?
Adv
- Higher spatial acuity
- Greater depth of perception
- Ability to focus
- Colour vision (also possible in compound eyes)
Disadv
- Slower at detecting movement
- Reduced sensitivity in low light environment
- More vulnerable to damage
What are short receptors?
self contained cells, that then stimulate afferent nerve
What are long receptors?
Contain afferent nerve, signal straight to the CNS
What are 2 ways signals can be amplified?
Ionotropic- signal directly activates channels
Metabotropic- signal binds to receptors, that leads to production of a secondary messenger e.g. cAMP
How does plant and animal signalling differ?
Plant commonly two component with receptor kinase (P histidine) and response regulator (P aspartate)
Animals - GPCRs or ionotropic
What is slow and fast adaptation to a stimulus?
Fast- receptor potential decreases rapidly, contains less firing of AP
Slow- receptor potential decreases over time, more firing of AP, over a long time
What are examples of short and long receptors?
Short- Hair cells, taste receptors
Long- ipRGC, olfactory, Meissner, Merkel, Pacinian, Ruffini
What receptor is present in the eye?
Gt PCR
alpha subunit detaches and activates PDE
PDE turns cGMP to 5’GMP
Cyclic nucleotide channel closes
Hyperpolarisation occurs
Lower levels of Ca2+ activates GC to make cGMP which restores the dark current
What is the difference between vertebrate and invertebrate phototransduction?
Vertebrate- ciliary receptors, ROD= membranous discs, CONE= invaginations of membrane, Gt pathway activated
Invertebrate- microvillar photoreceptors, called rhabdoms, activates Gq and PLC pathway
Describe archaea phototransduction
by phototaxis not GPCR
Photon leads to conformational change
Important in controlling flagella movement
Briefly explain how vertebrates transduce olfactory signals
1) Chemicals bind to olfactory receptors on the cilia
2) Golf is activated alpha subunit uncouples
3) Alpha subunit activates the cAMP pathway
4) cAMP opens cyclic nucleotide channels
5) Na+ and Ca2+ move in
6) Membrane is depolarised
7) Olfactory are long receptors so message sent straight to the olfactory cortex
