1
Q
What is osmoregulation?
A
Maintaining salt and water balance in the body
2
Q
Why do animals osmoregulate?
A
To avoid structural changes which can affect metabolic processes
3
Q
Difference in osmoregulation between terrestrials and aquatic animals
A
- Terrestrials must retain as much water as possible
- Aquatic must worry about salt levels more than water
4
Q
What are the 3 min body fluids?
A
- Circulatory fluid (ECF)
- Interstitial fluid (ECF)
- Intracellular fluid (ICF)
5
Q
Main goal of osmoregulation?
A
reduce fluctuations in intracellular ion concentrations
6
Q
Tissues maintain _________?
A
Osmotic balance
7
Q
Why regulate water and salt balance in the ECF instead of the ICF?
A
cause the ECF is the “middleman” for nutrient delivery and waste removal
8
Q
What is the primary extracellular fluid?
A
Circulatory fluid (blood)
9
Q
Most animal cells are polarized meaning?
A
- Different ion concentrations inside on outside the cells
10
Q
Where do animals maintain their difference in ion concentration?
A
Intracellular fluid (ICF)
11
Q
What influences water movement in and out of the cell?
A
Ion concentrations
12
Q
Are cells able to maintain an ionic difference or osmotic difference across a cell membrane?
A
Ionic difference
13
Q
Where do changes in ion concentration happen?
A
Extracellular fluid (ECF)
14
Q
2 main routes of water transport in epithelial cells
A
- Transcellular transport
- Paracellular transport
15
Q
Transcellular transport
A
movement through the cells across membranes
16
Q
Paracellular transport
A
movement between cells
17
Q
Osmotic pressure
A
amount of pressure needed to stop the movement of water by osmosis
18
Q
Osmotic gradient
A
The difference in osmotic pressure
19
Q
can water be actively pumped?
A
no
20
Q
Transport of water occurs through what process and via what?
A
Osmosis via the aquaporins
20
Q
A
21
Q
What does water movement mean for volume?
A
Area with high solute concentration now has higher volume than area with low concentration
22
Q
Osmolarity
A
the measure of solute concentration (# of osmoles per litre)
23
Q
Osmolality
A
of solutes per kilogram (osmol/kg)
24
Osmolytes
inorganic ions and organic molecules like glucose and protein
25
Changes in osmolarity cause?
a trans-membrane osmotic gradient where water moves affecting cell volume
26
Normal cell volume?
300 mOsm
27
Isotonic conditions
No net movement of water, no change in volume
28
Hypertonic conditions
Water diffuses out of the cells, cell shrinks
29
Hypotonic condition
Water diffuses into the cell, cell swells
30
3 classifications of solutes
1. Perturbing
2. Compatible
3. Counteracting
31
Perturbing solute effect on macromolecules
Disrupt macromolecular function
32
Counteracting solute effect on macromolecules
Disrupt molecular functions on their own
33
Compatible solute effect on macromolecules
little effect on macromolecular function
34
How do cells regulate volume?
Using regulatory mechanisms (ion transporters, ion channels)
35
Regulatory volume increase =
gain solutes
36
Regulatory volume decrease =
Solute loss
37
What are the effects of large changes in inorganic ions
detrimental for normal protein function
38
Where do we mostly see regulation occur?
In the ECF not the ICF
39
Three homeostatic processes
- Ionic regulation
- Osmotic regulation
- Volume regulation
40
Ionic regulation
concentrations of specific ions
41
Osmotic regulation
osmotic pressure of body fluids
42
Volume regulation
Total amount of water in body fluids
43
Osmoregulator vs Osmoconformer
- Osmoregulators osmotic pressure of body fluid is different than environment
- Osmoconformers body fluids are equal in osmotic pressure to environment
44
Maintain extracellular osmolarity and ion composition CONSTANT
Osmoregulators
45
Have strict extracellular osmotic homeostasis
Osmoregulators
46
Do not control osmotic conditions of extracellular environment
Osmoconformers
47
High degree of osmotic tolerance
Osmoconformers
48
Cells and tissues not able to cope with changes in extracellular osmolarity
Osmoregulators
49
Cells and tissues can cope with high extracellular osmolarity
Osmoconformers
50
Do freshwater animals have more or less concentrated ions than their environment?
More concentrated ions
51
Which way does water want to flow?
From the lower concentration to the higher concentration
52
Osmoregulation in freshwater fish
- Direction of water movement?
- Source of salts?
- Higher low salt loss?
- Drink amount?
- Water will enter the fish moving to higher concentration
- Gets salts from foods
- Low salt loss in urine
- Drinks little water
53
Osmoregulation in marine bony fish
- Direction of water movement?
- Source of salts?
- Higher low salt loss?
- Drink amount?
- Water exits the fish towards higher concentration
- Gets salts from foods
- High salt loss in urine
- Drinks lots of water
54
Most common strategy by marine invertebrates?
osmoconformation
55
Relation between osmotic pressure in the ICF and ECF in osmoconformers?
Have same osmotic pressure
56
Less energy expensive between osmoconformers and osmoregulation?
osmoconformers
57
Two types of marine environments and their differences
1. Stenohaline environment (Narrow range of environmental conditions)
2. Euryhaline environment
(large fluctuations in environmental conditions
58
What does the body excrete?
H+ Ions to keep pH of body fluids at neutral
59
Toxic products of metabolism
Nitrogenous compounds
60
What is nitrogen waste and what does it produce?
- Metabolism of proteins and nucleic acids
- Produces ammonia (NH3)
61
What is the problem with nitrogen waste?
Accumulation of ammonia (NH3) is toxic and must be excreted
62
Advantage of ammonia (NH3)?
is soluble is water but takes large amounts
63
Different strategies to deal with nitrogen waste
- Ammonia for aquatics
- Uric acid for terrestrial
- Urea for both
64
Ammonia
- Easily permeates across membrane
- Uses least energy
- Most toxic
- Requires most water
65
Urea
- Tolerated in more concentrated form
- Uses more energy to create
- Less toxic than ammonia
- Sacrifices less water
66
Uric acid
- Very insoluble in water, form precipitate
- Uses most energy to produce
- Non-toxic
- Least water required
67
Which nitrogen conversion pathway can be used as an osmolyte and how?
Urea, as it can help increase tissue osmolarity (reduce water loss) which can denature proteins
68
Osmoregulatory organs
- specialized internal organs "kidneys"
- External surfaces
- Gut
- Salt glands
69
Function of the osmoregulatory organs (kidneys)
- Regulate water and inorganic solute levels
- Remove nitrogenous waste and other metabolites wastes
70
The kidney requires extensive interaction between what?
Blood and osmoregulatory tubules
71
Outer layer of the kidney
Renal cortex
72
Inner layer of the kidney
Renal medulla
73
Drainage area in the center of the kidney
Renal pelvis
74
the smallest functional unit of the kidney
Nephron
75
Glomerulus
- Location
- Function
- Renal cortex
- Ultrafiltration (waste and useful molecules)
76
Bowman's capsule
- Location
- Function
- Renal cortex (surrounding glomerulus)
- Receives the filtrate
77
Renal corpuscle
Functional unit containing the Glomerulus and Bowman's capsule
78
Afferent arterioles
Brings blood to glomerulus
79
4 main processes of the nephron
1. Glomerular filtration
2. Tubular reabsorption - absorption
3. Tubular secretion - selective secretion
4. Excretion
80
Glomerular filtration
Non-selective filtering of blood into tubule
81
Tubular reabsorption
absorption of substances needed by body from tubule to blood
82
Tubular secretion
Selective secretion of substances to be eliminated from the body into the tubule from the blood
83
Excretion
resulting fluid is the urine
84
First step in urine production
Ultrafiltration
85
Proximal convoluted tubule
- All tubule exchange with blood is done by single layer of epithelial cells (Reabsorption and Secretion)
- Reabsorbes 65% of water
86
Transcellular exchange
Through the cell
87
Paracellular exchange
between the cells
88
Loop of Henle
establishes an osmotic gradient in the medulla
89
Filtrate starts at ____ mOsm and reduces it to _____ mOsm
300mOsm to 100mOsm
90
What % of water is reabsorbed at the loop of Henle? What's the total by the time it reaches the distal convoluted tubule
- 20%
- 65% + 20% = 85%
91
Descending limb
- Filtrate concentrates
- Permeable to water
- Impermeable to NaCl
92
Ascending limb
- Active Na+ and Cl- reabsorption
- Impermeable to water
- Permeable to NaCl
- Results in diluted filtrate
93
Role of urea
contributes to the osmotic gradient in the medulla
94
Distal convoluted tubule (DCT)
- Fluid reaching DCT is 20% of original filtered volume
- Fluid is HYPOtonic relative to plasma
95
Collecting duct
- Concentrates urine using osmotic gradient
- Permeable to water
96
Antidiuretic Hormone (ADH)
- released from pitituary gland when body is dehydrated
- Influences water permeability in DCT and collecting duct
97
Protonephridia
network of closed tubules with flame bulbs
98
Metanephridia
reabsorption and secretion from plasma into tubules
99
Malpighian tubules
blind-ended sacs off of hind gut
100
Salt glands
actively secrete NaCl
101
Respiration
exchange of oxygen (O2) and carbon dioxide (CO2) between internal and external environments
102
Why is there a constant urgent need for O2 in all animals?
Red blood requires oxygen as cellular processes rely on ATP which is produced by oxygen
103
Atmospheric pressure
Density of air in atmosphere
104
Where do we find large changes in pressure?
large altitudes
105
Does oxygen % change at high altitudes?
No, but partial pressure does
106
What is the difference run the air at higher altitudes
- Lower pressure
- Lighter and molecules are further appart
107
Air %
- O2
- N2
- CO2
- O2 = 21%
- N2 = 79%
- CO2 = <1%
108
Difference of oxygen in water
- O2 is less soluble
- Diffusion is slower
- O2 solubility influenced by temperature
109
Fick's Law of diffusion
J =
D =
A =
P1, P2 =
X =
J = rate of diffusion
D = diffusion coefficient
A = diffusion area
P1, P2 = pressures of gases
X = diffusion distance (thickness)
110
How do respiratory structures prevent respiration from being diffusion limited?
- Increasing surface area
- Reducing the thickness of the gas exchanger
111
Properties of a gas exchange membrane
- Thin layer of epithelial cells
- Separates internal tissues from environment
- Surface is moist for O2 to dissolve across
- Large capillary networks
112
Only way to depend on diffusion alone?
animal must be very very small
113
Oxygen cascade
- Pulmonary ventilation (breathing movements)
- Pulmonary diffusion
(diffusion of gas into epithelial cells)
- Perfusion
(transport of gas into circulatory system)
- Tissue diffusion
(diffusion of gas into tissues)
114
Main parts of respiratory system?
- Nose
- Mouth
- Pharynx
- Larynx
- Trachea
- Bronchi
- Bronchioles
- Alveoli
- Diaphragm
- Intercostal muscles
115
Describe the respiratory pathways
- Air enters nose of mouth
- Down the pharynx an Larynx
- Moves into the Trachea
- Trachea divides two bronchi
- Bronchi branch into bronchioles
- Bronchi branch into many alveoli
116
Site of gas exchange
Alveoli
117
Alveoli structure
- Surrounded by dense capillary network
- Composed of thin squamous epithelial cells
118
Boyle's Law
At any constant temp, pressure exerted by a gas is inversely proportional to its volume
119
Inhalation
an active process where the diaphragm contracts and rib cage expands
- Increase volume = decrease pressure
120
Exhalation
a passive process where the diaphragm relaxes going back to normal
- Decreased volume = increased pressure
121
what type of muscle is the diaphragm
skeletal
122
Tidal volume
Volume of air entering and leaving lungs in a single breath at rest
123
Inspiratory Reserve Volume
Additional volume of air that can be inhaled above resting TV
124
Expiratory Reserve Volume
Additional volume of air that can be exhaled above resting TV
125
Residual Volume
Minimum volume of air that remains in the lungs after a max exhalation
126
Why is there always air left in the lungs?
So that they do not collapse
127
Control of breathing
- Sensors
- Central Control
- Effectors
128
Chemoreceptors
Detect changes in O2
129
Mechanoreceptors
Stretch receptors in intercostal muscles and diaphragm
130
Respiratory muscles
- Intercostal muscles
- Diaphragm
131
Every cell in the insects body contacts with at least one _______?
tracheole
132
Air enters and leaves insects through different _________?
Spiracles
133
What do large insects do for gas exchange?
Contract abdominal muscles to create ventilation
134
respiratory system in birds
Contains air sacs and lungs
135
Bird lungs
- Do not expand or contract (rigid, always open)
- Contain parabronchi
- Surrounded by blood capillaries
136
Parabronchi
parallel tubes that contain air capillaries
137
In birds, lungs are attached to _________?
Air sacs
138
Air sacs
- Expandable
- Pressure changes move air in and out of lungs
139
Birds require ___ cycles of inhalation and exhalation for gas exchange
Two cycles
140
List the inhalation and exhalation
- 1st inhalation into deep air sacs
- 1st exhalation bring air into lungs
- 2nd inhalation push used air into anterior air sac
- 2nd exhalation will push air out of body
141
Blood movement through parabronchi is _______?
Cross-current
142
Blood capillaries move across _______?
Air capillaries
143
Gills
are evaginations of the body
(internal or external)
- Branched and folds = increased surface area
- Water must move over gills
144
What moves water over the gills?
Beating of cilia and contractions of body muscles
145
Mechanism used to flow water over gills
- Double-pumping mechanism (fish)
- Ram ventilation (sharks)
146
Double-pumping mechanism
Mouth and operculum direct water over gills in ONE direction
147
Ram ventilation
Swim with mouth open to direct water over gills in ONE direction
148
Gas exchange in the gill
Gill arches supplied with afferent and efferent blood vessels
149
Gill filaments contain ________?
Lamellae
150
Lamellae
Sites of gas exchange
151
Countercurrent exchange (gills)
water flows across gill lamellae in opposite direction of blood flow
152
Concurent flow
Blood and water flow in same direction
153
Oxygen transport in the blood
>98% of O2 bound to hemoglobin
<2% dissolved in plasma
154
Why is so little O2 dissolved in plasma?
Oxygen difuseability in fluid is low
155
Hemoglobin
- Composed of 4 polypeptide subunits
- Present in RBC's of almost all invertebrates
156
Where does oxygen bind on hemoglobin?
Binds to the Fe2+ in the haeme groups attached to each subunit
157
Why's it important that oxygen binds in a reversible manner?
Because we want oxygen to be released to the tissue
158
Hemoglobin can bing up to ___ O2 molecules
4
159
Hb-O2 dissocation curve
describes hemoglobins ability to bind O2
160
What does a left shifted Hb-O2 curve show?
Easier to bind O2 in lung, harder to release O2 at tissues
161
What does a right shifted Hb-O2 curve show?
Harder to bind O2 in the lung, easier to release O2 at tissues
162
What P50
Partial pressure required for 50%v of hemoglobin to be saturated
163
Why does CO₂ leave body tissues?
CO₂ diffuses out due to a PCO₂ gradient between tissues and blood
164
What are the three main ways CO₂ is transported in blood?
- 70% as H⁺ and HCO₃⁻ (bicarbonate ions)
- 20% bound to hemoglobin
- 10% dissolved in plasma
165
What enzyme helps convert CO₂ in red blood cells?
Carbonic anhydrase
166
What happens in the fast reaction of CO₂ conversion?
- H⁺ binds to hemoglobin
- HCO₃⁻ moves into plasma to buffer pH
167
What happens in the slow reaction of CO₂ conversion?
- CO₂ reacts with H₂O in plasma (no enzyme)
- H⁺ and HCO₃⁻ remain in plasma
168
Why is bicarbonate (HCO₃⁻) important in blood?
It helps buffer blood pH
169
What happens to H⁺ ions in red blood cells?
They bind to hemoglobin
170
Where do the reactions reverse?
In the alveoli (lungs)
171
Why is carbonic anhydrase important in the lungs?
It allows rapid and reversible conversion of CO₂ and bicarbonate.
172
Why have a circulatory system?
- Transporting water, respiratory gases and nutrients
- Remove waste products
- Temperature control
173
In all animals cells must?
- Have adequate O2, nutrients
- Eliminate toxic by-products of cell metabolism
174
Body composition of animals that rely solely on diffusion to and from the environment?
Only a few cell layer thick
175
Basic elements of a circulatory system
- Pump: movement of liquid
- Fluid: transport of solutes
- Vessels: contain fluid
176
Three types of circulatory systems
- No circulatory system
- Open circulatory system
- Closed circulatory system
177
What is the simplest type of circulatory system?
No circulatory system
178
How do organisms without a circulatory system transport substances?
Through water moving in a central cavity (gastrovascular cavity)
179
What is an open circulatory system?
A system with no separation between circulatory fluid and interstitial fluid
180
What fluid is pumped in an open circulatory system?
Hemolymph
181
Where does hemolymph flow in open systems?
Into the hemocoel (body cavity)
182
What molecule carries oxygen in many open systems?
hemocyanin
183
What organisms typically have an open circulatory system?
Invertebrates
184
What is a closed circulatory system?
Blood is kept separate from interstitial fluid in vessels
185
How does blood move in a closed circulatory system?
In a continuous circuit of vessels
186
What is the role of capillaries?
Allow fine control of blood flow distribution
187
What organisms have closed circulatory systems?
Vertebrates and cephalopods
188
What type of circulation is found in fish?
Single circuit
189
What are the heart chambers in fish?
1 atrium, 1 ventricle
190
Where is blood oxygenated in fish?
In the gills
191
What is blood pressure like in fish circulation?
Low
192
What animals have a parallel circuit?
Amphibians and most reptiles
193
What are the heart chambers in amphibians/reptiles?
2 atria, 1 ventricle
194
What is unique about the ventricle in amphibians/reptiles?
No division, so blood can mix
195
Where is blood oxygenated in amphibians/reptiles?
In the lungs
196
What is blood pressure like in amphibians/reptiles?
Low (similar to fish)
197
What animals have a double circulatory system?
Mammals and birds
198
What are the heart chambers in mammals/birds?
2 atria, 2 ventricles
199
What are the two circuits in double circulation?
Pulmonary circuit and systemic circuit
200
What is the pressure in the pulmonary circuit?
Low pressure
201
What is the pressure in the systemic circuit?
High pressure
202
What are the four main chambers of the mammalian heart?
2 atria and 2 ventricles
203
What is the function of atria?
Receive blood entering the heart
204
What is the function of ventricles?
Pump blood out of the heart
205
What do semilunar valves do?
Prevent backflow from arteries into ventricles
206
What do atrioventricular (AV) valves do?
Prevent backflow into atria
207
What causes heart valves to open and close?
Pressure differences
208
What does the right side of the heart do?
Pumps blood to lungs (pulmonary circuit)
209
What does the left side of the heart do?
Pumps blood to body (systemic circuit)
210
What is the cardiac cycle?
One full contraction and relaxation of the heart
211
What happens first in the cardiac cycle?
Atria contract, then ventricles contract
212
What is diastole?
Relaxation phase of the heart
213
What is systole?
Contraction phase of the heart
214
What happens to blood pressure during diastole?
Falls to ~80 mmHg
215
What happens to blood pressure during systole?
Increases to ~120 mmHg
216
How does pressure differ between circuits?
- Systemic (left side): high pressure
- Pulmonary (right side): low pressure
217
What type of heart is a mammalian heart?
Myogenic (initiates its own contractions)
218
Where does the heartbeat start?
Sinoatrial (SA) node
219
What is a neurogenic heart?
Controlled by the nervous system
220
What is the pathway of electrical conduction?
SA node → AV node → Purkinje fibres
221
Why is there a delay at the AV node?
Allows atria to contract before ventricles
222
What allows rapid spread of electrical signals in the heart?
Gap junctions
223
What type of muscle is cardiac muscle?
Striated muscle
224
What does the P wave represent?
Atrial depolarization
225
What does the QRS complex represent?
Ventricular depolarization
226
What does the T wave represent?
Ventricular repolarization
227
What is cardiac output?
Heart rate × stroke volume
228
What receptors detect changes for heart rate control?
Chemoreceptors and baroreceptors
229
Where is heart rate control integrated?
Medulla (CNS)
230
What is the effector in heart rate regulation?
The heart
231
What happens during the plateau phase of cardiac action potential?
Ca²⁺ influx allows sustained contraction
232
In what direction do ventricles contract?
From the bottom (apex) upward
233
What are the two main components of blood?
Plasma and cellular portion
234
What does plasma contain?
Dissolved gases, ions, and nutrients (fuel)
235
What makes up the cellular portion of blood?
RBCs, leukocytes (WBCs), and platelets
236
What is the function of arteries and arterioles?
Carry blood away from the heart
237
Why are arteries thick-walled?
To withstand high pressure
238
What is the function of veins and venules?
Return blood to the heart
239
Why are veins considered blood reservoirs?
They hold large volumes of blood at low pressure
240
How do veins prevent backflow?
With valves
241
How do skeletal muscles help venous return?
They compress veins to push blood back to the heart
242
What is the main function of capillaries?
Exchange materials with body cells
243
How thick are capillary walls?
One endothelial cell layer thick
244
What controls blood flow into capillary beds?
Precapillary sphincters
244
What are the three types of capillaries?
Continuous, fenestrated, sinusoidal
245
What regulates capillary blood flow?
Autonomic nervous system
246
How does blood velocity change in capillaries?
It decreases
247
Why is slower blood flow in capillaries important?
Allows efficient exchange with tissues
248
What is the fluid in the lymphatic system called?
Lymph
249
What is a key immune function of the lymphatic system?
Filtering foreign substances at lymph nodes
250
What fluid does the lymphatic system collect?
Excess interstitial fluid
251
Where does lymph fluid eventually go?
Back into venous blood before the heart
252
What is one role of the lymphatic system in homeostasis?
Maintains fluid balance
253
What digestive-related role does the lymphatic system have?
Fat Absorption
254
What is metabolism?
Body processes that use (input) and/or produce (output) energy
255
What is metabolic rate?
The rate at which the body uses energy
256
What are the three main energy sources for the body?
- Carbohydrates
- Lipids
- Proteins
257
How are carbohydrates used and stored?
- Used immediately as glucose
- Stored as glycogen
258
What is the energy characteristic of carbohydrates?
Provide the most energy per mol of O2
259
How are lipids stored in the body?
As triacylglycerol (triglycerides)
260
What must happen before lipids can be used for energy?
They must be broken down (requires energy)
261
Where else are lipids found in the body?
In the lipid bilayer membranes
262
What are the four structural levels of proteins?
Amino acids → alpha helix/beta sheets → subunit → complex
263
What are proteins mainly used for?
Structure, enzymes, transporters, antibodies
264
When are proteins used for energy?
Last option (after carbs and lipids)
265
What is the energy characteristic of proteins?
Provide the least energy per mol of O₂
266
What are the three fates of energy inputs?
Immediate ATP production
Build structural molecules
Stored for later use
267
What are the main categories of energy output?
Work and heat
268
How is daily energy typically spent?
- 70% organ function
- 20% physical activity
- 10% thermoregulation
269
How is metabolic rate measured?
By O₂ consumption and CO₂ production
270
What causes changes in metabolic rate?
Changes in ATP usage by cells
271
What two factors dictate metabolism?
Body size and thermoregulatory requirements
272
What is an endotherm?
Organism that generates metabolic heat to maintain body temperature
273
Give examples of endotherms
Mammals and birds
274
What is an ectotherm?
Organism that relies on the external environment for body temperature
275
Give examples of ectotherms.
Amphibians, reptiles, invertebrates
276
What is thermoregulation?
Ability to maintain a constant body temperature
277
What is a homeotherm?
Maintains a stable internal temperature
278
What is a heterotherm?
Can self-regulate AND use environment to control temperature
279
How is body temperature determined in ectotherms?
It is dependent on external environmental temperature
280
How does temperature affect metabolism in ectotherms?
Metabolism decreases in colder temperatures
281
What is behavioural thermoregulation?
Adjusting behavior (e.g., moving to warmer areas) to control body temperature
282
What is heterothermy in insects?
Heat is generated in specific body parts (e.g., flight muscles) but not retained
283
How does the thermoneutral zone (TNZ) shift in cold-adapted organisms?
It shifts left
284
What is regional heterothermy?
Different body regions maintain different temperatures
285
How do countercurrent heat exchangers help?
They reduce heat loss by transferring heat between blood vessels
286
Why is increased membrane fluidity important in cold environments?
Helps maintain cell function at low temperatures
287
How does the TNZ shift in heat-adapted organisms?
It shifts right
288
Why are longer appendages useful in hot environments?
They act as thermal windows to release heat
289
What are behavioral adaptations to heat?
Changes in activity patterns (e.g., being nocturnal)
290
How do endotherms maintain body temperature?
Independently of external temperature
291
What happens below the lower critical temperature (LCT)?
Metabolic rate increases to generate heat
292
What happens above the upper critical temperature (UCT)?
Metabolic rate increases to dissipate heat
293
What is the thermoneutral zone (TNZ)?
Range of temperatures where metabolic rate is minimal and stable
294
What is shivering?
Rapid muscle contractions to generate heat
295
What is vasoconstriction? (Heat management)
Narrowing of blood vessels to reduce heat loss
296
What is the role of brown adipose tissue?
Generates heat through metabolism
297
What is piloerection?
Hair standing up to trap insulating air
298
What is sweating?
Evaporation of water to cool the body
299
What is vasodilation? (Heat management)
Widening of blood vessels to increase heat loss
300
What are behavioral/postural cooling mechanisms?
Actions like spreading out or seeking shade to lose heat
301
302
What is the main goal of the digestive system?
To acquire energy
303
What are the four main functions of the digestive system?
Breakdown food, store food, absorb nutrients, eliminate unwanted food.
304
What are nutrients?
Substances essential for growth and maintaining life.
305
What are macronutrients?
Nutrients required in large quantities.
306
What are micronutrients?
Nutrients required in small amounts
307
Give examples of micronutrients.
- Vitamins
- Trace elements.
308
What are essential nutrients?
Nutrients animals cannot synthesize and must obtain from food.
309
Give examples of essential nutrients.
- Amino acids
- Fatty acids
- Vitamins
- Minerals
310
What can happen if there is an amino acid deficiency?
Reduced growth
311
What can happen if there is a fatty acid deficiency?
Increased risk of disease
312
What happens with mineral deficiency?
Reduced body system functioning
313
What happens with vitamin deficiency?
Reduced metabolic reactions
314
What is malnutrition?
Lack of one or more essential nutrients
315
What is undernutrition?
Consuming fewer calories than needed for daily activities.
316
What are the two main types of digestion?
- Intracellular
- Extracellular
317
What is intracellular digestion?
Digestion inside cells via endocytosis of food particles
318
What limits intracellular digestion?
The size of food particles
319
Give an example of organisms that use intracellular digestion
Sponges
320
What is extracellular digestion?
Digestion outside cells in a digestive cavity or tract
321
Where does extracellular digestion occur?
In a gastrovascular cavity or digestive tract.
322
Which organisms use extracellular digestion?
Most invertebrates and all vertebrates
323
What is a gastrovascular cavity?
A digestive compartment with a single opening
324
What are key features of a gastrovascular cavity?
- Lined with cells that secrete enzymes
- Absorb nutrients via endocytosis.
325
What is a digestive tract?
A tube with two openings (mouth and anus)
326
What is an advantage of a digestive tract?
- One-way movement of food
- specialized regions
327
What are the four main steps of digestion?
- Mechanical breakdown
- Chemical breakdown
- Absorption
- Elimination.
328
What is mechanical breakdown?
Physical grinding of food
329
What is chemical breakdown?
Enzymatic hydrolysis of food
330
What does hydrolysis mean in digestion?
Breaking chemical bonds using water
331
What type of digestion occurs in the mouth?
- Mechanical (teeth)
- Chemical digestion (saliva)
332
What enzymes are found in saliva?
- Amylase (carbohydrates)
- Lipases (triglycerides)
333
What triggers the swallowing reflex?
Food bolus pressing on touch receptors
334
Is swallowing voluntary or involuntary?
Involuntary (reflex)
335
What is the function of the epiglottis?
Prevents food from entering the trachea
336
How does food move through the esophagus?
By peristalsis
337
What opens to allow food into the stomach?
Gastroesophageal sphincter
338
What type of digestion occurs in the stomach?
- Mechanical (churning)
- Chemical digestion
339
What triggers gastric secretions in the stomach?
Stretching of the stomach
340
What do gastric glands secrete?
- Pepsin
- Gastric lipases
- HCl
341
What are the two main functions of the small intestine?
- Completes digestion
- Absorbs nutrients
342
What structures increase surface area in the small intestine?
- Villi
- Microvilli
343
Why does the small intestine have many blood and lymph vessels?
For efficient nutrient absorption and transport
344
What happens in the duodenum?
Receives bile and pancreatic secretions (enzymes + HCO₃⁻)
345
What is absorbed in the jejunum?
- Proteins
- Carbohydrates
- Fats
346
What is absorbed in the ileum?
Remaining essential nutrients
347
How are water-soluble nutrients absorbed?
By facilitated diffusion or active transport
348
What are examples of water-soluble nutrients?
- Amino acids
- Sugars
349
How are fat-soluble nutrients initially broken down?
By lipases and bile (micelles)
350
What happens to fatty acids inside intestinal cells?
Reassembled into triglycerides
351
How are fats transported after absorption?
As chylomicrons
352
What does the hepatic portal vein do?
Carries nutrient-rich blood from small intestine to liver
353
What is the role of the liver in digestion?
Chemical processing of nutrients
354
Where does blood go after leaving the liver?
Back to the heart, distributing nutrients
355
What is the main function of the large intestine?
Absorb water and ions
356
Does the large intestine perform digestion?
No significant digestive function
357
What is the shared function of the nervous and endocrine systems?
Maintaining homeostasis
358
How does the time scale of the nervous system compare to the endocrine system?
- Nervous: short-term effects
- Endocrine: long-term effects
359
What type of signals do both systems use?
Chemical messengers
360
What is a key similarity in how signals affect target cells?
They act as an effector cell
361
What is a major difference in signal transport between the two systems?
Endocrine signals travel through body fluids
362
What determines whether a cell responds to a hormone?
Presence of specific receptors
363
What is a gland?
An organ/tissue that synthesizes and secretes substances
364
What does “endocrine” mean?
Secreting molecules into extracellular fluid
365
What is autocrine signaling?
A cell targets itself
366
What is paracrine signaling?
Signals act on nearby cells via diffusion
367
What is endocrine signaling?
Hormones travel through the circulatory system to target cells
368
What is neuroendocrine signaling?
Neurons release neurohormones into the blood
369
What are three main roles of hormones?
- Respond to environmental stimuli
- Growth and development
- Homeostatic regulation
370
Give examples of environmental stimuli hormones respond to.
Day length and temperature
371
Why don’t all cells respond to every hormone?
Only cells with the correct receptors respond
372
What specific roles do the nervous and endocrine systems play in maintaining homeostasis?
- Nervous: rapid, targeted responses via electrical signals + neurotransmitters
- Endocrine: slower, widespread regulation via hormones in blood
373
Why are endocrine effects longer lasting than nervous system effects?
Hormones circulate in body fluids and persist longer before being broken down
374
Why can endocrine signaling occur in all animals, even simple ones like sponges?
It does not require a nervous system
375
Through what specific fluid do endocrine signals travel?
Extracellular fluid (including blood plasma)
376
What are the two main types of hormone receptors?
Cell surface receptors and intracellular receptors
377
In autocrine signaling, how does the signaling molecule reach its target?
It is released and binds to receptors on the same cell
378
In paracrine signaling, what limits how far the signal travels?
Diffusion distance in extracellular fluid
379
How do neuroendocrine cells differ from typical neurons?
They release hormones into blood, not just neurotransmitter at synapses
380
What triggers neuroendocrine cells to release hormones?
Electrical signals (action potentials)
381
How do hormones mediate responses to environmental stimuli?
By altering gene expression or cellular activity
382
What distinguishes endocrine signaling from paracrine signaling?
- Endocrine: long-distance via bloodstream
- Paracrine: local diffusion to nearby cells
383
How do sensory signals influence the endocrine system?
Communicate with the endocrine system via the hypothalamus and pituitary gland of the brain
384
What type of tissue is the posterior pituitary?
Nervous tissue
385
Does the posterior pituitary produce hormones?
No, it only stores and secretes hormones made by the hypothalamus
386
Which two hormones are released by the posterior pituitary?
- Oxytocin
- Antidiuretic Hormone (ADH)
387
What type of tissue is the anterior pituitary?
Glandular tissue (no neurons)
388
How many hormones does the anterior pituitary produce and secrete?
8 hormones
389
How does the hypothalamus control the anterior pituitary?
Via releasing and inhibiting hormones transported through the portal vein
390
What is the role of tropic hormones from the anterior pituitary?
They control other endocrine glands (ovaries/testes, thyroid, adrenal glands)
391
What are the main functions of growth hormone (GH)?
Regulates cell division and metabolic processes (energy conversion)
392
What are the effects of GH imbalance?
Deficiency: dwarfism
Overproduction: gigantism
393
What hormone stimulates the thyroid gland?
Thyroid-stimulating hormone (TSH) from anterior pituitary
394
What hormones does the thyroid gland release?
- T3 (triiodothyronine)
- T4 (thyroxine)
395
What do T3 and T4 do in the body?
- Increase metabolism
- Influence growth
396
What disorders result from thyroid imbalance?
Hyperthyroidism and hypothyroidism
397
What hormones are secreted by the islets of Langerhans?
- Insulin
- Glucagon
398
What is the function of insulin?
- Promotes breakdown of stored fuel
- Inhibits storage
399
What is the overall role of the adrenal gland?
Mediates the stress response
400
What does the adrenal medulla release and when?
Epinephrine and norepinephrine during short-term (sympathetic) stress
401
What is the function of epinephrine and norepinephrine?
Support fight-or-flight response
402
What does the adrenal cortex release?
Glucocorticoids
403
What is the function of glucocorticoids?
Prolong fuel mobilization for muscles during long-term stress
404
What is the key characteristic of sexual reproduction?
Combines genetic material from two parents → genetic diversity
405
What is the key characteristic of asexual reproduction?
Produces genetically identical offspring (no diversity)
406
What are the three mechanisms that increase genetic diversity in sexual reproduction?
- Genetic recombination
- Independent assortment
- Random fertilization
407
What is gametogenesis?
Production of haploid gametes in sex organs
408
Where does spermatogenesis occur?
Testes
409
How many sperm are produced from one diploid parent cell?
4 haploid sperm cells
410
How often are sperm produced?
Continuously (daily production)
411
What structures enable sperm function?
- Mitochondria → energy for movement
- Acrosome → enzymes to penetrate egg
412
What hormones regulate spermatogenesis?
FSH and LH
413
What is the role of LH in males?
Stimulates testosterone production
414
What is the role of FSH in males?
Stimulates sperm production
415
Where does oogenesis occur?
In the ovaries
416
When are primary oocytes formed?
Before birth
417
How many ova are produced per ovarian cycle?
One
418
What surrounds the ovum?
Zona pellucida
419
What hormone does the hypothalamus release to start reproductive hormone signaling?
Gonadotropin-releasing hormone (GnRH)
420
What does GnRH stimulate?
Release of FSH and LH from anterior pituitary
421
What do FSH and LH do in females?
- Stimulate oocyte development
- Estrogen production
422
What hormonal changes trigger ovulation?
Drop in estrogen + spike in LH and FSH
423
What happens to estrogen and progesterone after fertilization?
They increase and remain high
424
What is the first step of fertilization?
Sperm contacts zona pellucida
425
What happens during the acrosome reaction?
Release of hydrolytic enzymes to break down zona pellucida
426
What happens after sperm penetrates the egg coating?
Sperm binds to vitelline layer
427
What occurs when sperm enters the egg?
Plasma membranes fuse
428
What is the fast block to polyspermy?
Membrane depolarization
429
What is the slow block to polyspermy?
Zona pellucida hardens via IP₃–Ca²⁺ signaling
430
What is the final step of fertilization?
Fusion of sperm and egg nuclei
431
What is oviparous development?
Egg-laying, development outside the body
432
What is viviparous development?
Live birth, development inside uterus
433
What is ovoviviparous development?
Eggs develop inside parent without direct nourishment
434
435
What is fertilization?
Formation of a diploid zygote from haploid gametes
436
What is cleavage?
Rapid mitotic cell divisions after fertilization
437
What happens to the zygote during cleavage?
It is partitioned into smaller cells (blastomeres) without growth
438
Why doesn’t the embryo increase in size during cleavage?
No new cytoplasm is added
439
What is a morula?
A solid ball of cells formed during cleavage
440
What is a blastula?
A hollow sphere of cells with a single cell layer
441
What is holoblastic cleavage?
Complete cleavage of the entire egg
442
What is meroblastic cleavage?
Incomplete cleavage (only part of egg divides)
443
What is totipotency?
Ability of a cell to differentiate into any cell type
444
How does totipotency vary among blastomeres?
It differs between cells depending on development type
445
What is mosaic development?
Blastomeres have predetermined, restricted fates
446
In which organisms is mosaic development common?
Protostomes
447
What is regulative development?
Blastomeres retain totipotency and can adjust development
448
Up to what stage can blastomeres remain totipotent in regulative development?
16–64 cell stage
449
In which organisms is regulative development common?
Deuterostomes
450
What is gastrulation?
Cell movement and division forming germ layers
451
What are the three germ layers?
Ectoderm, mesoderm, endoderm
452
What does “triploblastic” mean?
Having three germ layers
453
What is invagination?
Inward folding of cells at the blastopore
454
What is the archenteron?
The primitive gut cavity
455
What is the blastopore?
Opening that forms during gastrulation
456
How do protostomes develop?
- Mouth forms first
- Mesoderm forms near blastopore
- Coelom forms by schizocoely (splitting)
457
How do deuterostomes develop?
- Anus forms first
- Mesoderm forms from archenteron
- Coelom forms by enterocoely (outpocketing)
458
What is organogenesis?
Formation of organs via cell differentiation, migration, and apoptosis
459
What is apoptosis?
Programmed cell death
460
What is the first major step in organogenesis?
Neural crest formation
461
What structure induces neural plate formation?
Notochord
462
What happens during neural tube formation?
Neural plate folds inward and pinches off
463
What does the neural tube develop into?
Central nervous system
464
What structures form from mesoderm near the neural tube?
Somites
465
What do somites develop into?
Vertebrae and ribs
466
What happens to the notochord in vertebrates?
It is temporary and replaced
467
What is metamorphosis?
Development into an adult form with specialized structures and functions
Biology 224
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