Animals Flashcards
(311 cards)
1
Q
Name the 3 types of skeletons
A
Hydrostatic
Exoskeleton
Endoskeleton
2
Q
How does the skeleton produce movement?
A
Resists the pull from skeletal muscles
3
Q
Describe hydrostatic skeletons
A
Muscles surrounding a fluid filled cabity exert pressure to produce movement
4
Q
Describe hydrostatic skeleton in an earthworm
A
Fliud filled cavity. Circular muscle. Longitudinal muscle.
5
Q
What is a circular muscle?
A
Forms a circle all the way round. Contract = narrower and longer
6
Q
What is a longitudinal muscle?
A
Length ways - flatter and shorter
7
Q
Describe an exoskeleton.
A
External to organs and soft tissue
8
Q
What are Mollusc shells made of?
A
Composite material: calcium carbonate and protein
9
Q
How does protein affect an exoskeleton?
A
More flexible - less likely to snap
10
Q
Describe an Arthropod exoskeleton. (A cuticle)
A
Contains chitin embedded in a protein matrix. Arthropods have joints so needs to be flexible.
Chitin = long fibrils.
Cross linking between proteins.
Hardened by calcium carbonate
11
Q
Describe an endoskeleton?
A
Skeleton inside thebody. Vertebrates.
12
Q
What can the skeleton be divided into?
A
Axial and appendicular
13
Q
What are the axial regions of the skeleton?
A
Spine, ribcage, skull
14
Q
What are the appendicular regions of the skeleton?
A
Bones appended on the acial
15
Q
What does bone contain?
A
Collagen (1/3). Calcium phosphate crystals (strengthens).
16
Q
What would happen if bone had no minerals?
A
It would bend
17
Q
What would happen if bone had no collagen?
A
Would be too brittle - likely to snap
18
Q
What is brittle bone disease?
A
Mutation - less collagen
19
Q
What are osteoblasts?
A
bone producing cells, secrete enzymes, collagen production
20
Q
What are osteocytes?
A
mature bone cells, encased in the bone
21
Q
What are osteoclasts?
A
break down the bone
22
Q
What is osteoperosis?
A
bone weakness → increased breaking down of bone compared to making bone
23
Q
How are skeletons able to move?
A
Joints
24
Q
What are the different types of joints?
A
Hinge Ball and socket Plane Pivot Condylar Saddle
25
How is the type of joint formed determined?
By the shape of the end of thebone
26
What is torque?
Rotational movement of an object arpimd am axid
27
What is the equation for torque?
t = F x r
28
Which type of levers have more range of moevement?
Long levers
29
What are the main functions of the skeleton?
Movement. Protection. Support
30
What are the 3 types of muscle?
Heart. Smooth. Skeletal
31
What is the smallest unit of muscle?
Muscle fiber - muscle cells
32
How are muscle fibers formed?
Fusion of lots of cells - they are multinucleated
33
What is the name of a bundle of fibers?
Fascicle
34
What is the epimysium?
connective tissue - outside, surrounds all the muscle, continuous
35
What is perimysium?
connective tissue - surrounds fascicles
36
What is endomysium?
connective tissue - surrounds individual muscle fibres
37
Describe myofibirl
```
2 overlapping myofilaments
Thick = myosin
Thin = actin
Secured by the Z disc
Known as the sarcomere
```
38
Describe muscle contraction.
```
Increased overlap
Contraction → sarcomere shortening
Shortening of muscle
Size of filaments doesn’t change
They overlap by binding
```
39
Describe thin filaments
Actin
Contains binding sites for myosin
Binding sites covered by tropomyosin
When calcium is present → tropomyosin moves off
40
Describe thick filaments
Myosin
Binding site for actin and one for ATP
Contain a tail and a head
Myosin heads protrude out ready to bind
41
Describe binding in the sliding filament theory
Bond = cross bridge
ATP binds to myosin head
Dissociation of myosin and actin
ATP broken down → ADP and Pi
Myosin head pulled back to ‘cocked’ position
Myosin can now bind to actin as ATP is no longer present
ADP + Pi released → myosin head moves back (power stroke) → thin filament slides across the thick filament
42
Describe contraction coupling (excitation)
Motor neuron connects to muscle fibre through the neuromuscular junction
T-tubules close to sarcoplasmic reticulum → calcium store
Action potential propagates along sarcolemma to T tubules
Sensed by sarcoplasmic reticulum → releases calcium
43
How do T tubules work?
```
high density of calcium channels (DHPR)
Opens
Influx of calcium ions into muscle cell
Channel from sarcoplasmic reticulum
Massive of influx into muscle cell
```
44
What is the equation for aerobic respiration?
O2 + glucose → CO2 + H2O + ATP
45
What is the respiratory membrane?
where gas exchange takes place
46
How do the simplest invertebrates get nutrients?
gas exchange occurs across the entire surface of the organism and diffusion of the gases is sufficient
47
What is ventilation?
movement of respiratory medium to respiratory surface eg breathing
48
What is diffusion?
movement of gases across respiratory membrane
49
What is circulation?
system to carry gases around the body → usually movement of fluid
50
What are 3 respiratory surfaces?
gills, tracheae, lungs
51
Describe the gills
```
Outfoldings of respiratory membrane
Highly complex as there’s low oxygen concentrations in water
Really thin
Huge surface area
Moist
```
52
What are gills like in a salamander?
external gills
53
What are gills like in a bony fish?
internal gills
54
Describe breathing in a bony fish
2 sets of gills either side
Ventilation → through the mouth and over the gills
Achieve by swimming continuously
Operculum → flap covering gills → can expand drawing in water
Gill arches contain gill filaments → discs lamellae
Countercurrent → blood in opposite direction to waterflow
55
What is the oxygen uptake like in terrestrial animals?
Oxygen uptake = higher
56
How do insects breathe?
Through a tracheal system
57
Describe the open circulatory system in insects
Open circulatory system not involved in transporting gases
All cells bathed in respiratory medium
Doesn’t need to be transported
Can just use diffusion
58
How do insects ventilate?
rhythmic body movements
59
What is the process of breathing in insects?
Spiracles (air enters) → large tube called tracheae (strengthened by chitin) → air flows through smaller tubes (tracheoles)
60
What does having lungs mean?
Restricted to one location and so requires circulatory system to transport gases to cells
61
Where does the air move through in a human?
in through nose and mouth to pharynx → trachea → bronchi → lungs → branch into small bronchi → and bronchioles → alveoli
62
Where does gas exchange occur in the lungs?
Alveoli
63
What are the alveoli surrounded by?
A dense bunch of capillaries
64
What are features of alveoli?
Thin. Form a large surface area.
65
Describe ventilation in a human.
Inhalation and exhalation
Diaphragm contracts
Moves down
Lungs expand
Draws the air in → pressure gradient → negative pressure
Pressure drops and volume increase (inversely proportional)
Exhalation → passive → diaphragm relaxes
66
How can frogs respire?
Through the skin (in water) or via the lungs
67
Describe the process of respiration in a frog
Mouth floor lowers, air flows in
Reduces pressure → volume increases
Mouth floor contracts forcing air into the lungs
68
How do birds ventilate?
Using air sacs
69
What air is in the anterior air sac?
Stale air
70
What air is in the posterior air sac?
Fresh air
71
Describe respiration and ventilation in a bird.
Lungs (parabronchi) are unidirectional
Inhalation → air sacs fill
Has valves
Exhalation → air sacs empty, lungs fill
Need 2 rounds for air to be completely circulated
Need to be efficient → high energy for flight → huge oxygen requirement
Crosscurrent flow → blood flows at an angle to the air flow
72
Describe haemoglobin.
4 subunits → globular protein
2 Alpha subunits
2 Beta subunits
Heme group → oxygen binding site → iron group Fe2+
73
How is oxygen carried in the blood if its not soluble in blood?
Iron ion binds to the oxygen
| Can bind 4 molecules of oxygen
74
What happenns when a molecule of oxygen binds to haemoglobin?
Binding causes a conformational change in the haemoglobin → makes it easier for future molecules to bind
75
What is the Bohr effect?
```
pH affects
Lower pH moves to the right
Reduces affinity
Less oxygen binding
Lactic acid in active muscles
A drop in pH
Affinity for oxygen is reduced
More likely to release oxygen
```
76
What organisms can use diffusion?
Single celled and simple multicellular organisms
77
Why do larger organisms need a circularotry system?
Diffusion happens at one spot and then is deilvered y a circulatory system
78
What is an open circulatory system?
- Fluid is pumped through a large muscular tube
- Fluid propelled through
- Rhythmic contraction of muscles
- Fluid leaves tube and empties into the body cavity
- Vessels are open ended
- Cells are bathed in the fluid
79
What are some examples of organisms with an open circulatory system?
Invertebrate. Arthropods.
80
What is the circulatory fluid in organisms with an open circulatory system called?
Hemolymph
81
What are the problems with an open circulatory system?
1. Limited control over where to divert fluid
| 2. Lower pressure
82
What is a closed circulatory system?
- Fluid is pumped through closed ended vessels
- Uses a pump eg the heart
- Higher pressure is created
83
What are cells in a closed circulatory system organism bathed in?
Interstitial fluid (outside of vessels)
84
What does a vascular network mean for an organism?
There is more control
85
What do interstitial fluid and blood have in common?
Composition - water and ions
86
What is blood composed of?
Proteins. Blood cells. (Too big to leave vessels)
87
Describe the features of interstitial fluid.
- Environment the cells are exposed to
- Involved in homeostasis
- Ionic gradient maintained by Na+/K+ ATPase
88
What are the 5 main categories of vessels?
1. Arteries
2. Arterioles
3. Capillaries
4. Venules
5. Veins
89
Describe the structure and function of the artery
- Wall = thick
- Blood pumped into from the heart
- High pressure
90
Describe the structure and function of the capillaries.
- Thin walls
- Where gas exchange/diffusion takes place
- 1 cell thick
- Allows gases and nutrients to pass through
91
Describe the structure and function of the veins
- Lowest pressure
- Don't need thick walls
- Valves to prevent backflow
- Muscles push against the veins
92
What are the 3 layers in blood vessels?
Inner layer. Middle layer. External layer.
93
What is the inner layer in a blood vessel?
Tunica intima. Endothelium.
94
What is the middle layer in a blood vessel?
Tunica media. Elastic and smooth muscle
95
What is the external layer in a blood vessel?
Tunica adventitia. Provides support
96
What happens every time a vessel branches?
Gets smaller in diameter but get many more vessels
97
What does vessel branching mean for an organism?
Can quickly direct blood eg to skeletal muscle. Cardiac output increases
98
How are arteries the primary site for blood flow regulation?
- Tissues more active
- More ATP
- More oxygen needed = greater blood supply
- Drop in oxygen
- Detected by smooth muscle
- Aterioles dialte
- Less resistance
- Increased blood flow
99
What is autoregulation?
Decresses blood pH. Increased K+ prostaglandins, adeonisne
100
How does adenosine regulate blood flow?
- Increases during exercise
| - More blood flow through femoral artery
101
Describe blood flow in a fish.
- Heart = 2 chambers
- Single system
- Flows through the heart once
- Low pressure
- Not very active --> not possible for land animals
102
What is meant by double circulation?
Goes through the heart twice. Two different circuits
103
What is the pulmonary circuit?
heart → lungs → heart
104
What is the systematic circuit?
heart → body → heart
105
Describe circulation in amphibians and reptiles.
- 3 chambered heart
- Empty into ventricle
- Higher pressure
- Mixing oxygen rich and oxygen poor blood
106
How many heart chambers do birds and mammals have?
4. 2 atria and 2 ventricles.
107
Describe the blood flow in a double circulatory system?
Blood → left ventricle → supplies capillary beds → returns to right atrium → right ventricle → pumped to lungs → returns to left atrium
108
What are the features of the vena cava?
Vena Cava → deoxygenated blood → largest vein
Inferior = lower
Superior = upper
109
Where does blood flow in the right atrium?
Right atrium → blood flows from right atrium to right ventricle
110
Where does blood flow from the pulmonary artery?
Takes blood to the lungs
| Have right and left branches
111
Where does blood flow from the right ventricle?
Blood is ejected to the lungs
| Through pulmonary artery
112
What blood does the pulmonary veins carry?
Oxygenated blood
113
Where does blood from the left atria flow?
flows to left ventricle
114
Where does blood from the aorta flow?
branches to direct blood
Arteries to head and arms
Abdominal aorta
115
Where does blood from the left ventricle flow?
Pumps to aorta
116
Why is the left wall so much thicker than the right in the heart?
Higher pressure
117
What happens during atrial systole?
Contraction of both atria. Blood flows into the ventricles
118
What happens during ventricular systole?
Contraction of the ventricles. Isovolumetric contraction
Start to contract but no blood ejected yet
Not enough pressure
Ventricular ejection
Blood leaves and enters the arteries
119
What happens during ventricular diastole?
Isovolumetric relaxation
Started to relax but no change in volume
Ventricular filling
Passive
120
Why do we need nutrients?
To produce energy
121
What is the gastrointrestinal tract?
Involved in digestion - extracellular. Specialised body cavity. Gut
122
What are the 5 main functions of the gastrointestinal tract?
1. Ingestion
2. Digestion
3. Absorption
4. Secretion
5. Excretion
123
What happens at the mouth?
Chew - breakdown
124
What happens at the salivary gland?
Saliva produced - digestion
125
What happens when food travels down the pharynx and through the esophogus?
Digestion ceases because of the low pH
126
Where does the majority of digestion take place?
Intestines
127
How is food digested in the intestines?
aided by secretions from secondary structures eg liver, gallbladder and pancreas
128
What happens when food has been digested in the intestines?
Produce substances which travel into the small intestine
Now the food is in small enough pieces it can be absorbed into the bloodstream
Majority of absorption in the small intestine
129
What happens at the anus?
Waste is secreted
130
What are the 3 sections of the GI tract?
1. Foregut (mouth , esophagus, stomach)
2. Midgut (small intestine)
3. Hindgut (Large intestine, rectum)
131
What is the main component of the diet?
Carbohydrates
132
What are the different types of carbohydrates?
Monosaccharides. Dissacharides. Polysaccharides
133
What is starch composed of?
Amylose and amylopectine
134
Describe the features of starch.
D-structure → form amylose
Alpha 1-4 bonds in both amylose and amylopectin
Amylose → linear structure
Amylopectin → alpha 1-6 bonds as wells → creates branching → more effective storage molecule
135
Describe the structure of glycogen
Has alpha 1-4 and alpha 1-6 bonds
| Many more 1-6 bonds than amylopectin so lots more branching
136
Describe the function of glycogen
More effective storage form
| Glucose at ends can be broken off easily
137
What does amylase do?
Breaks down amylose into monomers. Works on alpha 1-4 bonds.
138
What are the 2 forms of amylases and where are they found?
1. Salivary amylase (mouth)
| 2. Pancreatic amylase (duodenum - upper part of small intestine)
139
Can dissacraides and trisaccharides be absorbed?
NO
140
How are broken down carbohydrates absorbed?
- Transported out of small intestine lumen
- Through intestinal cell
- Into blood stream
141
What are brush border enzymes?
Enzymes present on the membrane of our intestinal cell
142
What does maltase do?
Splits maltose into 2 glucose molecules
143
What does sucrase do?
Breaks disaccharide into glucose and fructose
144
What does lactase do?
Lactose into glucose and galactose
145
What are the 2 main processes involved in absorption?
1. Cotransport
| 2. Facilitated diffusion
146
Why does there need to be 2 layers of absorption?
- Get through apical membrane (in contact with lumen)
| - Get thorugh basolateral membrane (close proximity to the bloodstream)
147
Describe glucose and galactose cotransport across the apical membrane
- Use the SGLT transporter
- Sodium-glucose linked
- Cotransport
- Sugar crosses the membrane in addition to an ion → in this case sodium
- Sugar binds and sodium ion binds → when both have bound → both transported
- Don't need a concentration gradient for the sugars the concentration gradient for the sodium ions is enough
148
Describe how fructose is transported.
Facilitated diffusion
Protein transporter that shuttles fructose
Needs a concentration gradient
149
What do fructose, galactose and glucose need for facilitated diffusion?
GLUT2
150
Describe the experiment with SLGT?
stopped it working → monitor the uptake → look at AMG
glucose /galactose diet → lose weight
Fructose diet → carry on as normal
151
What are proteins broken down into?
Amino acids
152
What are proteins digested by?
Peptidases - act on peptides
153
What do endo peptidases do?
Break interior bonds - at the centre
154
What do exo peptidases do?
Cleave terminal amino acids
155
What is pepsinogen?
The inactive precusor of pepsin
156
Why does pepsinogen have to be activated?
De to the low pH don't want to break down proteins that the body needs
157
What is found in the lining of the stomach?
Gastric pits
158
What is in gastric pits?
- Chief cells - secrete pepsinogen
| - Parietal cells - secrete acid, ensure the low pH
159
What causes the majority of protein digestion occur?
Trypsinogen (produces by the pancreas) - trypsin (continues digestion)
160
How are amino acids absorbed?
By cotransport - sodium or hydrogen ions are used
161
What is the main form of fats?
Triglycerides
162
What is the composition of triglycerides?
3 fatty acids and a glycerol molecule
163
What enzyme breaks down fats?
Lipases
164
What form are fats absorbed in?
Monoglyceride and 2 free fatty acids
165
What are the different forms of lipases and where are they found?
1. Lingual lipases - mouth
2. Gastric lipases - stomach
3. Pancreatic lipases - small intestine
166
What is the issue caused by fats not being soluble in water?
- Form large globules in the small intestine lumen
| - Lipases can't penetrate the globule they could act around it but it would take too long
167
What does digestion of fats require?
Bile salts (secreted by the liver)
168
How do bile salts help digestion of fats?
- Amphipathic molecules
- Polar and non-polar surfaces
- Penetrates inside
- Breaks them into small fat droplets
- Creates an emulsion
- Easier for the lipases
169
Describe the absorption of fats
- Diffuse through apical membrane
- Easy and passive
- As the products build up → lose concentration gradient
- Sends products to SER
- Repackaged back to triglycerides
- Moved to the golgi → packaged into chylomicrons
- Enter the bloodstream
170
What are Chylomicrons?
- Quite big
- Leave via exocytosis and enter circulation via lymphatic system
- Much bigger gaps
- Eventually merge
171
What is the problem with eating plants?
Cellulose - digested by cellulase which animals do not have
172
Describe cellulose.
Has beta 1-4 bonds and every other glucose has a different arrangement
173
How do bacteria aid cellulose digestion?
Symbiosis - has cellulase
174
What are foregut fermenters?
Rumen and reticulum (cows helped by regurgitation)
175
What are hindgut fermenters?
Bacteria in cecum (rabbits less efficient)
176
What are the products of fermenters?
CO2 and mthane - which is why cows contribute to global warming
177
Describe the features of the small intestine
- Long
| - Big SA (folding and microvilli)
178
What does a shark have instead of a small intestine?
Corkscrew structure - increased surface area
179
Why is the intesetinal surface area greater for mammals?
- More active
| - Absorb more nutrients = more energy
180
What is meant by metabolism?
Producing, using and storing energy
181
What is catabloic metabolism?
Breakdown. Large to small. Breakdown through oxidative phosphorylation
182
What is anabolic metabolism?
Building up. Small monomers to large polymers.
183
How is storage related to metabolism?
Control of energy metabolism.
184
Why is control of metabolism important?
- Only eat at certain times of the day
- Need a store to be broken down
- Controlled by hormones and the nervous system
185
Where is glucose stored?
As glycogen in the liver and skeletal muscle (1%)
186
Where are amino acids stored?
Skeletal muscle (22%)
187
Where are lipids stored?
Adipose tissue (77%). Stored as triglycerides
188
Why doesn't the body like using proteins as energy?
Involves breaking down muscle
189
What does energy balance mean?
That the energy intake is equal to the energy otuput
190
Where do we gain energy?
Food and diet
191
What are examples of energy output?
- Basal (70%)
- Activity (20%)
- Thermoregulation (10%)
192
What happens if there is an energy imbalance?
Change in fat stores and therefore in body shape
193
What is basal metabolic rate (BMR)?
Psychologically and physically rested, post absorptive state and thermoneutral
194
What happens if you have a high metabolism?
Faster break down - can afford to eat more
195
What is the average BMR in an adult?
20 - 25 kCal/kg/day
196
What factors affect BMR?
Body weight. Lean body mass. Age. Diet.
197
What is resting metabolic rate?
Amount of energy you are consuming whilst doing nothing
198
How is RMR measured?
Through Direct Calorimetry or Indirect Calorimetry
199
Describe Direct Calorimetry.
- Measure heat produced
- Endotherms release heat
- Amount of heat produced is directly proportional to energy
200
Describe Indirect Calorimetry
Amount of oxygen consumed
Oxygen → ATP
Respirometry
201
What are the problems with measuring direct calorimetry?
- Difficult to measure small heat changes
| - Body stores heat
202
What are the problems with measuring Indirect Calorimetry?
depends on macromolecule being oxidised
Fatty acids → have to use much more oxygen to oxidise and produce the same amount of ATP as glucose
Fats therefore may look like they’re using more energy
203
What is the RQ quotient?
CO2 produced/O2 consumed
204
What is the RQ value for respiration using glucose?
1
205
What is Kleiber's Law?
- Larger animals have less surface area to volume → ⅔ law
- Metabolic rate increases to how quickly they can get rid of heat
- Kleiber disputed the ⅔ law thought to be due to the branching as an animal gets bigger
- Nutrients → more efficient → don't spend as much energy distributing energy
- Evolutionary drive to get bigger
206
What source of energy to we first use when active?
Phosphocreatine
207
Describe how phosphocreatine works?
- Precursor of ATP
- Donates a phosphate to ADP
- Doesn't last long
208
What process is used after phosphocreatine during activity?
Glycolysis - doesn't require oxygen
209
What is used during prolonged activity?
- Aerobic respiration
- Produces the most ATP
- High mitochodnrial content
- Glucose used preferentially
210
Describe an endotherm
- Generate own heat → internal source
- Heat derived from metabolism → production of energy
- Makes living on land possible
- Tolerate wild temperatures
- Allows a high level of activity
- Function more often over a large range of temperatures
- Produce energy to produce heat → energetically expensive → fuel metabolic activity
211
Describe an ectotherm.
- Body temperature dependent on environment
- Produce some energy → but the heat doesn’t really contribute
- Less active
- Lots of times of the year not at optimum temperature
- Lower food intake → not relying on metabolism
212
What is conduction?
Direct transfer → one surface to another
213
What is convection?
Movement of air/water over the body surface
214
What is radiation?
Surfaces hotter than 0 will release electromagnetic waves
215
What is evaporation?
Loss of heat during evaporation of water
216
How is body insulation used as thermoregulation?
- Reducing heat loss
- Hair, feathers, fur, subcutaneous fat (blubber)
- Fur traps air
- Fur is 6x more effective that blubber
- Need much more blubber
- Air → poor thermal conductor
217
How is the circulatory system used as thermoregulation?
- Constriction of vessels → reduces heat loss
- Dilation of vessels → increases
- Hypothalamus → monitor temperature
- Negative feedback
Countercurrent heat exchange
218
Describe what happens when a drop of temperature is detected in an endotherm.
hypothalamus → directs blood away from the skin → vasoconstriction
Temperature rise → hypothalamus → vasodilation
219
What is countercurrent heat exchange?
Extremities
Eg flippers on dolphins
Eg legs on birds
Blood flows in opposite directions → heat is exchanged → warming of the blood as it re-enters the core of the body
220
How is evaporative heat loss used as thermoregulation?
- Heat loss across the surface of skin through water
Sweating
- Panting
221
Describe the process of sweating
```
Mediated by hypothalamus
Activates sweat glands
Moisture of body surface
Most common in humans
Less so in animals
```
222
Describe the process of panting
Stick tongue out and pant
| Encourages evaporative heat loss
223
How is behavioral used as thermoregulation?
- Bask in the sun
- Sunbathing
- Seek shade
- Huddling
- Burrowing
224
How is changing rate of metabolism used as thermoregulation?
- Heat produced is key to maintaining body temperature
- Increasing movement
- Shivering
- Non- shivering thermogenesis
225
How does increasing movement aid thermoregulation?
- Moving more → body needs more energy
- Generates heat as a by product
- Raise body temperature → move about more
226
Describe the process of shivering.
- Short, fast contractions of skeletal muscles
| - Requires energy
227
Describe Non-Shivering thermogenesis
Subconscious
Always occurring
Occurs in brown fat tissue
228
What is UCP?
uncoupled movement of protons
Energy production more wasteful
Halve to burn more fuel to produce the same amount of energy
229
How is UCP involved in ATP production?
- Pump protons
- Out of mitochondria
- Large proton gradient
- Then moves through ATP synthase
- Sneak protons in and reduce proton gradient
- Reduce the driving force
- Metabolism has to move at a higher rate
230
Describe Torpor and Hibernation.
Higher need for food
Wild animals → reduced food availability or decreased temperature
Torpor is a state of inactivity decreased metabolic rate and reduced body temperature
Hibernation is longer term than torpor → through the winter for example
Torpor → shorter period of time
231
What is osmosis?
The passive movement of water molecule from an area of high water concentration to an area of low water concentration
232
What is isotonic?
same amount of solvents inside and out
| Same osmotic pressure - no net movement
233
What is hypertonic?
```
high solutes outside than inside
Water will leave the cell
Lower water concentration outside
Cell shrinkage
Water leaving
```
234
What is hypotonic?
high solutes inside the cell
Water enters the cell
Higher osmotic pressure
Cell will swell and rupture
235
Where is water gained?
Mouth - food and drink. Metabolism product
236
Where is water lost?
Urination. Respiration. Body surface
237
What is an osmoconformer?
- Animal whose body fluids are isosmotic with the external medium → identical to environment
- Typically invertebrates
- Typically in seawater
238
What is an osmoregulator?
- Animal that maintains osmotic pressure of its body fluid independent of the external medium
- Majority of animals
- Have to balance
239
What are euryhaline animals?
- Tolerate wide variations in osmotic pressure of the external medium
- Eg rainbow trout or a salmon → live in the sea and then move to rivers where they spawn
- Tolerate changes
- High and low osmotic pressures
- Quite rare
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What are stenohaline animals?
- Have very limited tolerance of variation in osmotic pressure of external medium
- Only tolerate one environment
241
Describe osmosis in a saltwater fish.
- More solutes in seawater
- Net movement out
- Occur at skin and the kidney
242
How does the saltwater fish prevent water loss?
- Produces concentrated urine
- Drink seawater
- Take in excessive salt
243
Describe the process of saltwater fish pumping salt in
- Gill filaments there are chloride cells
- Pumping out salts coming in through the mouth
- Pump out chloride and therefore sodium will follow down its electrochemical gradient
244
How do Sharks regulate water?
- High urea cocnentration
- Increase pressure internally
- Will close osmotic gap
- Urea is toxic but have TMAO to counter the effect
245
Describe water regulation in a fresh water fish.
```
Higher osmotic pressure internally
Driving force is to enter
Prevent excess water gain
Have chloride cells → pump salt into the body → ensures internal is higher
Don't drink water
Some ingested during feeding
Skin is impermeable to water so no excess water entering
Dilute urine
```
246
Describe water regulation in Land Animals
- Concerned about excess water loss → dehydration
- Lose 12% = fatal
- Prevent loss → key role
247
Describe water regulation in humans
Intake → drinking, in food and a product of metabolism
Lose about 2.5L per day → evaporation, urine and feces
Can tweak concentration of urine depending on hydration status
248
Describe water regulation in a Kangaroo Rat
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adapted to hot environment → low water requirement → 60ml
90% through metabolism
Dry environments
Produce very concentrated urine
Evaporation main source of water loss
```
249
What are the 2 main areas of the kidney?
Renal cortex. Renal medulla.
250
What is the functional unit of the kidney?
Nephron
251
What happens when the blood enters a nephron?
- Goes through Bowman's capsule
- Glomerulus (large surface area)
- Blood is filtered
- All fluid and small particles leave capillaries and enter nephron
RBCs and big proteins stay in the bloodstream
252
Where does the filtrate travel.
PCT. Loop of Henle. DCT. Collecting Duct
253
What gets reabsorbed?
Salts. Glucose. Amino acids. Fluids.
254
What happens to anything left in the collecting duct?
Taken to the bladder and excreted
255
Describe Blood Filtration.
- Glomerulus/Bowman’s capsule
- Blood is filtered
- Fluid and small solutes leave the bloodstream and enter the nephron
- Proteins and RBCs stay in the capillaries
256
Describe Reabsorption.
- Filtrate → through nephron
- Water → important solutes are reabsorbed
- Important compounds leave the nephron and enter the bloodstream
- Prevent a net loss of fluids
257
Describe Secretion
- Regulate ions
- High potassium in bloodstream → secrete excess
- Get rid in the urine
258
Describe Excretion
Anything left in the kidney will be excreted into the urine
259
Describe water reabsorption in the PCT
- Passive reabsorption of solutes (sodium, glucose)
| - Water will follow the ions through osmosis
260
Describe water reabsorption in the Loop of Henle
- The countercurrent multiplier
- Water reabsorbed
- Osmotic gradient needed → high to low
261
What occurs in the ascending limb?
- Sodium/chloride actively pumped out
- Impermeable to water
- Water stays in
- Raises concentration round the outside → increasing osmotic pressure
262
What occurs in the Descending Limb?
- Descending limb → experiences high osmotic pressure → water moves out → passive water
- Further down it becomes more concentrated
263
Describe water reabsorption in the DCT
- Reabsorption of sodium → mediated by the hormone aldosterone
- Aldosterone → `affects sodium reabsorption
- Sodium levels drop → aldosterone → acts on DCT → increases sodium reabsorption → water naturally follows → passive
264
Describe water reabsorption in the Collecting Duct
Antidiuretic hormone → ADH
Directly related to hydration status
More ADH → increase water reabsorption → less water is lost
265
What are the stages of ADH being released?
1. Initial trigger
2. Osmolarity of extracellular fluid
3. Osmoreceptors detect and respond
4. Signal to posterior pituitary gland
5. Secretes ADH
6. Negative feedback
7. More concentration urine
8. Keep more water in the body
266
Where is ADH released from?
Pituitary Gland
267
What are the stages of ADH acting on the collecting duct cell?
- ADH binds to specific receptor
- Sets up a secondary signalling cascade
- Increase activity of protein kinase A
- Signalling molecule
- Translocation of vesicles to membrane of interior collecting duct
- Vesicles contain aquaporins → eg aquaporin 2
- Aquaporin channels added to the membrane
268
How is water regulated in insects?
Through malpighian tubules - series of tubules which wrap around the gut
269
How do the malpghian tubules work?
Intake food at mouth
Travels through digestive tract → digested and absorbed
Extend out into extracellular fluid
Open → hemolymph → passive diffusion of water and solutes and waste into tubules
Travels through GI tract → water and important solutes absorbed
No separate systems for water and feces
270
What happens if there is too much energy intake?
Weight gain. Store as fat - lead to bad health
271
What happens if there is too much energy output?
Weight loss. Once all the fats have been broken down then your body will start to break down muscle.
272
What part of the body is responsible for the regulation of food intake?
Hypothalamus - signals if we're hungry or full
273
Where are the different places that can signal to the hypothalalmus in food regulation?
- the gut - eg if something is in the gut
- hormones - stimulate feeling of hunger or fullness
- bloodborne - related to energy stores
- psychological - bored, stressed, out of habit
274
Describe the hunger signal
- Stimulates the orexigenic pathway
- Hypothalamus triggers this
- Results in us feeling hungry
- Reduces our energy expenditure → slow down what we’re using up
275
Describe the satiety signal
- Causes us to stop feeding
- Stimulates the anorexigenic pathway
- Triggered by the hypothalamus
- Anorexia → physiological response, feeding is inhibited
276
What are the 3 hypothalamic regions involved in food regulation?
1. Arcuate nucleus (ARC)
2. Lateral Hypothalamic Area (LHA)
3. Ventromedial Nucleus (VMN)
277
What are the 2 sets of neurons that the Arcuate nucleus contains?
1. NPY/AgRP
| 2. POMC/CART
278
What does NPY/AgRP do?
Act on LHA to increase feeding (orexigenic)
279
Describe the process of NPY/AgRP
- Release the neurotransmitter NPY
- Peptide release from the ARC
- Travel to the LHA region
- Neurons respond by releasing a peptide (orexins) which results in hunger
280
What does POMC/CART do?
Act on the VMN to reduce feeding (anorexigenic)
281
Describe the process of POMC/CART
- Release a peptide called melanocortin
- Act on the VMN region
- The neurons in the VMN release CRH which results in the feeling of fullness
282
What is the experimental study that has been done to support the food regulation pathways?
n rats → day 0 was when neuropeptide injections began
Before this food intake was similar in all animals
Immediately after the injection NPY food intake dramatically increases → especially compared to the control animals
Proves that NPY is part of the orexigenic pathway
This stops almost immediately after these injections stop
283
How do signals in the gut help with food regulation?
- Activation of strechc receptors from stomach distention (vagal nerve)
- Stomach expands when we eat
- Vagus nerve carries signals to the hypothalamus if there's a lot of food to stop eating
284
What is the vagus nerve?
Afferent sensory nerve which relays information to the CNS
285
How can nutrients have a similar effect?
- Break dwon food
- Nutrients can inform the CNS to stop eating
- Stimulates the anorexigenic pathway
286
Which nutrients can directly trigger the hypothalamus?
Glucose amino acids and fatty acids
287
Why do nutritionists recommend a high protein diet?
Amino acids have the most powerful effect - feel fuller after a high protein meal
288
How are hormones used in the short term in food regulation?
- Relay information about whether the gut is full of empty to hypothalamus
289
What hormones are released in the fed states?
1. Cholecystokinin (CCK)
| 2. Insulin
290
What effect does Cholescystokinin (CKK) have?
- Main
- Released from the gut during feeding
- Increases the release of digestive enzymes
- Aid digestion
- Tell the hypothalamus that food has been ingested
291
What effect does insulin have?
- Blood glucose
- Insulin released after a meal
- Can also send a message to the hypothalamus
292
What hormones are released in the fasting state?
1. Ghrelin (Ghr)
2. Glucagon
3. Adrenaline
293
What effect does Ghrelin (Ghr) have?
- Powerful trigger of hunger
| - Levels peak just before a meal
294
What effect does glucoagon have?
Are reelased not sure if they affect feeding
295
What effect does adrenaline have?
Are released not sure if they affect feeding
296
How are hormones used in the long term regulation of food?
- Amoutn of stored energy affects how much you eat
| - Feel less hunger if we have more stored energy
297
What is the hormone responsible for appetite based on our energy stores?
Leptin - secrete from adipose tissues
298
How does Leptin work?
Reduces feeling by suppressing NPY and stimulating CART neurons
299
Describe an experiment with leptin in mice.
ob/ob mouse → leptin deficient mouse → cant produce leptin → just keep eating and eating and eating regardless of stored energy → can’t switch off the feeling of hunger
300
When might humans have high leptin levels?
If they are obese
301
Why are people still obese even if they have high leptin levels?
- Psychology
| - Could be leptin resistant
302
What are some ways of treating obesitiy behvaiourally?
1. Diet
| 2. Exercise
303
What are some ways of treating obesitiy Pharmacologically?
1. Phentermine
2. Phendimetrazine
3. Diethylpropion
4. Orlistat → doctors might recommend but not lightly
304
What are some ways of treating obesitiy surgically?
1. Restrictive surgery
| 2. Malabsorptive surgery
305
During muscle contraction what initiated the power stroke?
Release of ADP
306
What is hydroxyapatite composed of?
Calcium and phosphate
307
What is the gap between a motor neurone and the sarcolemma of skeletal muscle?
Synaptic cleft
308
What is pulmonary respiration?
Moving air into and out of the lungs
309
What are the portions of the brain that contain respiratory centres?
Medulla and pons
310
How do Cnidaria and flatworms exchange gases and remove waste?
Gastrovascular cavities
311
What would you find in the heart of an amphibian?
Two atria and one ventricle
