exam - processes/structures Flashcards
(138 cards)
1
Q
respiration
A
exchange of gases - most animals use aerobic metabolism to sustain resting energy requirements
2
Q
small animals can achieve gas exchange by
A
diffusion
3
Q
Larger, more complex animals require
A
specialised gas exchange surfaces
4
Q
water as medium for gas exchange
A
water has higher density, viscosity, greater resistance to diffusion, water has greater capacitance for CO2 than O2
5
Q
concentration of gas in water calculation:
A
[O2]=BO2 x PO2
6
Q
exchanging gases
A
Oxygen must pass from external environment to mitochondria
- must dissolve in water then pass through successive membrane to reach mitochondria (diffusion)
- diffuse provided there is a partial pressure gradient (passively)
7
Q
rate of diffusion across a surface depends on
A
partial pressure gradient across membrane (change P)
- properties of membrane: permeability, SA, thickness
8
Q
Fick’s Law
A
conductance = permability x SA x pp gradient / thickness
9
Q
breathing in =
A
decreased thickness, increased area = better diffusion as SA increases
10
Q
SA and volume relationship in small organisms
A
ratio of SA:V is greater for samll species, so diffusion from environment to mitochondria only effective in small organisms
11
Q
Ventilation
A
boundary layer - still air or water around an organism can be stagnant, needs to be reduce by lungs ventilating, fish swimming, etc.
convection of the external medium at the site of gas exchange that is generated by the animal - maintains favourable pp!
12
Q
Evolution of large animals was dependent on the development of:
A
- A gas exchange medium and ventilatory mechanism
- An internal transport system
13
Q
countercurrent mechanisms
A
increases efficiency of gas exchange
- water passes over gills in opposite direction to blood flow = maximises partial pressure of O in water and blood
14
Q
fish transition to land
A
air breathing fish gulp air from surface using buccal-force pump to push air down into gas bladder
15
Q
lungs developed…
A
as outgrowths of the gut, specialised for respiration in air
- tidal ventilation results in rebreathing of air (less efficient but ok as air higher in Oxygen)
16
Q
amphibian respire via
A
buccal-force pumping to ventilate lungs and cutaneous respiration
17
Q
reptiles ventilate lungs…
A
using aspirating pump (sucking air in) by moving body wall to create a negative pressure to draw are in
18
Q
crocs ventilate lungs using
A
M. diaphragmaticus muscle attached to pelvis, pulls back drawing liver back, cavity bigger = lungs can expand
19
Q
turtle respiration
A
ribs are stuck as shell, so have muscles that move based on limb movement, sucks air in or pushes air out (have to move to breathe!)
20
Q
mammal lungs structure
A
- trachea branches into each lung via a bronchus
- bronchus divides into many smaller bronchioles
- ends in small sac like alveoli, whose walls are thin and highly vascularised
21
Q
mammal lungs function
A
- gas exchange occurs in alveoli
- lungs ventilated when muscular diaphragm contracts and ribs expand to increase space around lungs in pleural cavity (create negative space)
22
Q
bird lungs process
A
High metabolism, so need more oxygen
- unidirectional air flow
- parabronchi associated with air sacs, which act as bellows (not a gas exchange surface)
- air enters through parabronchi and passes into capillaries
complicated flow system, one way only and continuous, lungs always being ventilated
23
Q
insect respiration
A
spiracles allow air to enter, tracheae carry gases to and from tissues, branch into fluid filled tracheoles, occurs via passive diffusion
has size limit
24
Q
Spider lungs
A
book lungs = numerous horizontal air spaces that connect to outside via a spiracle. bring haemolymph in close contact with air.
25
aquatic insect respiration
mosquito larvae - spiracle modified into snorkel
diving beetles trap air bubbles
26
circulatory systems
- Within cells, movement occurs by diffusion and cytoplasmic streaming
- Diffusion also occurs between cells but it is slow
- Animals that rely on diffusion must be small
- Larger animals require circulation systems
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circulatory system functions
- Transport gases + nutrients + wastes + hormones
- Redistribute heat
- Allow transmission of force
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open circulatory system
can only support low metabolic rate, energetically cheap, heart pumps hemolymph in sinuses and bathes organs
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close circulatory system
can support high metabolic rate, energetically expensive, heart pumps blood through blood vessels
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vertebrate circulatory systems
mammals use left systemic arch and birds use right systemic arch - evidence that they developed independently (convergent)
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patterns of circulation - fish
heart has a single atrium and ventricle, single circuit: heart - gills - body tissues, blood pressure in gills is greater than in the rest of body
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amphibian circulatory system
2 separate atria, some mixing, dual system
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reptiles circulatory system
2 atria single ventricle, some tissue between to try separate blood a bit, dual circulatory system (goes back to heart after lungs)
34
crocodile circulatory system
2 atria and 2 ventricles completely divided
- unique amongst reptiles, formaen of panizza (opens when not breathing - when underwater can put deox blood back around body)
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mixing of blood
- In fish, amphibians and reptiles = some mixing of blood occurs
- Low MR
- Regulated
no mixing in mammals and birds - high MR, always breathing
36
4 chambered heart (mammals and birds)
complete separation of pulmonary and systemic circulations
order = right atria, lungs, left, body
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coronary =
circulation supplying heart with blood
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pulmonar circuit steps
1. Deox blood enters right atrium and passes into right ventricle
2. Blood enters pulmonary artery
3. Blood is oxygenated in capillaries of lung alveoli
4. Oxygenated blood returns to heart via pulmonary vein into left atrium
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systemic circuit
1. Oxygenated blood enters left atrium and passes into left ventricle
2. Enters aorta
3. Blood is deoxygenated in capillary beds of body
4. Deoxygenated blood returns to heart via vena cavae
40
left side of heart is...
thicker as it has to pump blood further
41
electrical activity of heart
vertebrate heartbeat is myogenic, muscle fibres contract independently - must be coordinated to provide a functional heartbeat.
- cycle initiated by a sinoatrial node (pacemaker of the heart)
42
cardiac cycle
control of the contraction and relaxation of area of the heart muscle
- systole = blood is pushed around body
- diastole = relaxation phase, where heart fills
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cardiac cycle steps
1. atria contract
2. node delays ventricle contraction
3. reaches apex
4. ventricles contract
44
arteries
thick walled, 4 layers of tissue
elastin in wall maintains a more even blood pressure
- systole pressure expands walls of arteries, limited by outer layer of collagen
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veins
thin walls due to lower pressure, blood circulates in veins through local muscular compression, majority of blood volume
46
micro-circulation - capillaries
composed of a single layers of endothelial cells, site of exchange, numerous and very small
47
capillary exchange
via diffusion, larger molecules and lipi-insoluble materials pass by pinocytosis
- pressurised fluid is forced through discontinuities and fenestrae between the cells in the process of filtration
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lymphatics
lymphatic capillaries collect interstitial fluid, flow due to the contraction of smooth muscles, lymph hearts.
- lymph passes through lymph nodes before entering venous system
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lymphatic system role in fluid balance
- Transports lipids from small intestine to the blood
- Transports liver products
- Important in immune defence
50
Support structures - buoyancy
upward force that a liquid exerts on an object that you immerse in it
B = density x volume x acceleration (from gravity)
51
water and air density
water = 1000kg per cubic m, air = 1.3kg per cubic m
52
aquatic vs terrestrial skeleton
aquatic = hydrostatic skeleton to resist deformation
land = solid skeleton
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hydrostatic skeleton
fluid filled space surrounded by a flexible wall - action of circular and/or longitudinal muscles surrounding this cavity pressurises this fluid
- can change shape = locomotion
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worm locomotion
peristaltic locomotion
shorten body = longitudinal muscles contract
lengthen body = circular muscles contract
55
cellular hydrostatic skeletons
in Acoelomate animals and leeches
- parenchyma cells in place of fluid filled cavity
- leeches have coelom filled with botryoidal tissue = looping or crawling movement
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hydro skeleton limits
- limited to small animals
- lack of protection
- limited mechanical support against gravity
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solid skeletons
consist of rigid material with higher mechanical strength = exoskeleton and endoskeleton
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exoskeleton
- Provide excellent protection
- Offer mechanical advantages
- Comparatively heavy and limit body size
- Moulting necessary (negative)
Scratches and cracks may weaken it
can be single piece (snail), 2 piece(bivalve) or multi piece (arthropod)
59
chitin exoskeleton
- Occur mostly in invertebrates
- Formed when hard skeletal material is deposited on the external body surface
Composition varies among taxa
- chitin is insoluble, pliable, resilient and tough, similar structure to cellulose
60
CaCO = biomineralisation exoskeleton
- Increases strength and hardness
- Heavier
- snails, corals
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composite exoskeleton
crustaceans and molluscs often combine chitin and calcium carbonate in their exoskeleton
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moulting
Arthropod exoskeletons must be moulted
- Moult is controlled by hormones
- Porthoracicotropic (PTTH) hormone
63
insect locomotion
2 muscle types: skeletal and visceral
- skeletal attach to cuticle via microtubules
Muscle cells and epidermal cells interdigitate (mesh together)
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arthropod locomotion
- Walk, run, crawl, burrow, fly, swim
- Joints in exoskeleton allow for movement
- Limbs articulate with the body and with themselves
Dicondylic joints permit movement in a single plane
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wings
- Wings are part of exoskeleton
- Veins contain nerves and trachea
- Occur on the 2nd and 3rd thoracic segments
- Facilitate flight
Also used for protection, sound production, visual communication, orientation and thermoregulation
66
wing muscle types: direct
- Muscles connect directly from the pleuron to the sclerites at the base of the wing
Wings have a single pivot point eg. dragon flies
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wing muscle indirect
- One set of muscles connected to the tergum and the sternum
Another set of muscles connected to the anterior and posterior regions of the thorax
- no connection of muscles to wings = real flies
68
endoskeleotn - cartilage
consists of connective tissue: cartilage
- cartilage is composed of chondrocytes in a matrix of chondroitin sulfate
- flexible but strong
- no blood or nervous system supply
3 forms
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3 forms of cartilage (H, F, E)
- Hayaline matrix appears homologous with few collagen fibres
- Fibrocartilage is reinforced with numerous collagen fibres. Resistant to tensile or warping loads and compressive forces (disks in spine)
Elastic cartilage is springy due to elastic fibres in the matrix (ears, epiglotis)
70
endoskeleton: bones
consist of collagen and hydroxyapatite
- in living tissues, consists of osteocytes embedded in the collagen hydroxyapatite matrix
- 2 main types of cells: osteoblasts and osteoclasts
- renewal of bone is responsible for bone strength through life
71
collagen provides (in skeleton)...
tensile strength and flexibility
72
hydoxyapatite is...
a form of calcium phosphate that resists compression and provides strength
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bones are capable of...
adaptive change: atrophy = not used, hypertrophy = very used
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bone types
compact bone = very dense
cancellous (spongy) bone = less dense
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compact bone
protective outer shell, only some small cavities that contain osteocytes, nerves and capillaries
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cancellous bone
- Found at the ends of long bones and deep within the interior of short bones (away from direct surface loading)
Centre of bone contains:
- Red marrow in which stem cells reproduce
- Yellow marrow which stores fats
- Bone cells
- Lymphatic and blood vessels and nerves
77
osteocytes
- Osteoblasts are responsible for bone matrix synthesis
- Secrete minerals that bond with the newly formed osteoid to mineralise the bone tissue
- Osteoclasts secrete the bone-reabsorbing enzymes, which digest bone matric
78
endochondral ossification
- Species with a bony skeleton have an embryonic cartilage skeleton that is progressively replaced by bone as they mature and develop
○ Cartilage is deposited early in development into shapes resembling the bones-to-be
Some regions retain cartilage in the adult
79
endochondral ossification steps
1. spongy bone forms
2. osteoclasts form central cavity of long bones
3. perichondrium forms around the cartilage and begins forming compact bone
4. blood vessels form and grow
5. in juveniles, 2 bands of cartilage remain as the bone developes, at either end of the bone
80
joints are
articulations between bones that allow muscles to act to produce movement
81
2 types of joints
sliding = occur in vertebrates
elastic = soft, pliable material that allows part of otherwise rigid skeletal element to bend
82
vertebrate 3 functional groups of joints
- Immovable, with edges that tightly interlock (cranial bones)
- Partly moveable, with some flexibility and usually cartilage between bones (spine)
- Freely moveable - a lot of flexibility (knee)
83
geometry, shape, position of ligaments determine possible movement...(HSPBEG)
- Hinge allows extension and retraction of appendage (elbow)
- Saddle allows movement back and forth and up and down
- Pivot allows rotation around an axis (neck)
- Ball and socket = radial movement (hip)
- Ellipsoid = similar to ball and socket (wrist)
Gliding or plane = bones slides past each other (top of feet)
84
ligaments are
strong bands of collagenous material attached to bones on either side of joints (maintain orientation)
- keep joint surfaces pressed together
- strengthen and stabilise joints
85
tendons are...
connective tissue that link muscles to bones
86
how skeletons allow for movement
one skeletal element forms the origin and the other the insertion - insertion is lever, which moves about the fixed articulation point, the fulcrum
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1st class lever
- fulcrum located between muscle effort and load (head on neck - seesaw, ME left)
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2nd class lever
- load located between fulcrum and muscle effort (foot - wheelbarrow, ME right)
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3rd class lever -
muscle effort between fulcrum and load (ME middle)
90
which kever system can exert greatest force
lever system with muscle effort directed further from fulcrum than the load distance
91
mechanical advantage (MA) =
ratio of load to muscle effort
92
range of motion (ROM) =
distance a load is moved by a muscle contracting a distance and it is proportional to the distance of the load from the fulcrum
93
muscles
muscle cells are specialised to actively contract and product tension
- convert chemical energy of ATP into mechanical energy
94
microfilaments are...
polymers of protein subunits - 2 main types are actin and myosin
95
Actin
2 protofilaments comprised of 100 globular subunits - high concentration in skeletal and cardiac muscle cells
- like 2 strings of beads
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Myosin
long rod shaped molecule of 2 protein chains
has a head = globular part of the heavy meromyosin end
97
myosin 1
monomeric myosin = 2 single hockey sticks
98
Myosin-2
polymerised myosin molecules (many lumped together with bare zone in centre)
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troponin and tropomyosin
regulate the interaction of actin with myosin
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muscle types
striated (skeletal and cardiac) and smooth, then further divide into voluntary and involuntary
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sarcomere
Highly ordered array of thick myosin and thin actin filaments (alternating)
- Actin molecules are attached to the Z line at each end of the sarcomere
- Myosin filaments extend in parallel between the ends of the sarcomere
- Myosin filaments are held in place at the M band
102
Sliding filament model steps (BPDR)
1. Binding: myosin cross bridge binds to actin molecule
2. Power stroke: cross bridge bends, pulling actin filament inward to sarcomere's centre
3. Detachment: ATP binds to myosin head, causing it to detach
4. Repeated cycling: cross bridge binds to more, keeps going
103
Actin-Myosin regulation of sliding filament model (for striated muscle=Ca!)
1. Resting state (tropomyosin blocks binding sites, preventing contraction
2. Calcium release (when nerve stimulated, Ca is released)
3. Binding to troponin (Ca binds to troponin = change in structure, so myosin heads can now bind to actin)
4. Initiation of contraciton (binding sites exposed, myosin forms cross bridges and contraction can occur)
104
what ions are required for muscle contraction?
calcium and magnesium
- Mg2+ is an enzymatic cofactor for ATPase activity
- Ca2+ regulates Myosin head ATPase activity, and actin-myosin interaction in striated muscle
105
Excitation-contraction coupling
1. Skeletal muscles are stimulated to contract by the arrival of acetyl-choline (Ach) = motor neuron
2. The muscle generates an action potential
3. Spread of the action potential down the t-tubule releases Calcium from the sarcoplasmic reticulum
4. elevated Calcium then elicits a localised sarcomeric contraction
106
muscle contraction - what stimulates it
electrical impulse elicits a contraction - is determined by both its magnitude and duration
107
threshold stimulation - Rheobase
= threshold voltage for a very long duration impulse that elicits a response
108
- Utilisation time =
shortest duration that elicits a contraction of a rheobase-level stimulus (difficult to measure)
109
Chronaxie =
minimum duration for a 2x rheobase voltage - is a measure of the excitability of the cell
110
2 types of muscle contraction
isometric contraction = muscle generates tension but length of muscle doesn't change
isotonic contraction = muscle shortens, maintaining a constant force
- most animal muscles contract as a combination of both
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contraction time course
- A single electrical stimulation of a muscle elicits a single contraction or twitch
- Latency period - delay between the electrical stimulation and the first increase in tension
- Maximum isometric tension occurs at 150 msec after stimulus
- Relaxation is complete after about 900 msec
112
summation
occurs if a second twitch is initiated while the muscle is still generating tension from the first twitch
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tetany
- A series of successive contractions will cause continual summation of twitches
- While individual contractions are discernible this is incomplete tetany
- Complete tetany occurs if the frequency if stimulation is increased to the fusion frequency
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locomotion types
crawling, walking/running, burrowing, swimming, gliding, flapping flight
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crawling - snakes (SCRS)
- Serpentine = s shaped curves, muscles contract in waves, fast movement
- Concertina = used in tight spaces, anchors part of body and extends forward, pulls rest along
- Rectilinear locomotion = straight line (heavy snakes) by alternately contracting and relaxing belly muscles
Side winding= used on slippery surfaces, throws part of body sideways
116
walking and running
- Body mass is supported on only a few points of contact with the substrate
- Legs are alternately raised and lowered
Body equilibrium must therefore be maintained
117
reptiles and amphibians walking
sprawled posture with limbs placed laterally
- Vertebral column undulates laterally about pivot points during locomotion
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evolutionary trend towards cursorial locomotion (walking)
Major structural change in limb design, Vertical rather than lateral flexion of the vertebral column
- torsion brings digits forward and in line with direction of travel
- increases ease and efficiency of limb oscillation
119
gait
pattern of limb movement, varies between animals and with speed
RF = relative phase between cycle of each foot
DF = duty factor, the fraction of time that the foot is on the ground
120
walking/running foot postures
plantigrade = entire sole of foot on ground
digitigrade = digits support weight
unguligrade = travel on tips of toes
121
jumping
causes extreme disequilibrium, very low DF
- height jumped relates to mass and velocity
- aerodynamic drag is a decelerating force and decreases jump height
122
metabolic cost of walking/running
depends on velocity, terrestrial locomotion has a linear increase with velocity, not linear if gait changes
123
burrowing metabolic cost
very high
124
aquatic locomotion
- Density of a fluid medium provides a substantial buoyant force
- Movement of objects through fluid medium creates drag and sometimes lift forces
- Direction of drag force is parallel to direction of fluid flow
125
swimming
- Pushing against the external fluid medium allows for generation of a thrust force for swimming
126
generating thrust to swim depends on...
the properties of the medium, the size of the organisms and the type of swimming mechanism
127
reynold's number = Re
ratio of inertial forces to viscous forces
- big when inertial forces dominate, small when viscous forces dominate
128
direction of drag force is...
parallel to the direction of fluid flow
129
total drag =
friction drag as surface and pressure drag
- fish use drag to swim, undulatory movements generate drag and thrust and push against the medium.
130
the hydrodynamic force of a fish tail resolves into...
a drag and lift force - useful for forward thrust
131
swimming - hydrofoil tail
stiff and shaped like a wing - generates both lift and drag
132
lift =
force exerted on an object by a fluid perpendicular to the fluid motion
133
metabolic cost to swim =
drag x velocity
134
aerial locomotion
Glide or flying are constrained by same set of fluid dynamic principles as swimming
- Drag and lift provide propulsive force for locomotion
135
differences between swimming and flying
- Air has lower density than water
- Air has higher kinematic viscosity than water
136
gliding
- Animal moving downward and forward, air path = upward and backward
Aerodynamic force = lift and drag forces, L >> D
- can only maintain both forward velocity and altitude if air has vertical component
- No direct metabolic cost to gliding, but uses energy to keep wings rigid
137
flapping flight
- Birds bats insects use muscular energy to generate aerodynamic lift
- For larger animals, both up and down strokes generate forward thrust resulting in constant forward thrust and lift
138
3 types of power required for flight muscles
○ Parasite power - Energy used to overcome drag on the body
○ Profile power - Power used to overcome drag on the wings themselves
Induced drag = Power required to generate lift
