Animal Biology Flashcards
1
Q
Give an overview of animal development
A
- fertilization forms the diploid zygote
- three embryonic stages:
- cleavage: converts the unicellular zygote into a multicellular embryo
- blastula: a hollow ball of cells
- gastrulation: 3 germ layers are formed - differential gene expression is the foundation of the diverse cell types and behaviours seen throughout development
- morphogenesis occurs via changes in cell position, shape, survival, and forms organs
2
Q
Why are model organisms easy to study for development?
A
- developmental genes and mechanisms are very similar across animal species
- studying development provides knowledge about development in general
THESE ORGANISMS ARE ONLY BROADLY REPRESENTATIVE!!
3
Q
Fertilization: ______ ______ join to form a _____ ______
A
haploid gamete; diploid zygote
4
Q
Explain fertilization in sea urchins
A
- sperm and egg are the haploid gametes
- contact with the jelly coat triggers the acrosomal reaction
- surface proteins on acrosomal process bind to receptors on egg cell membrane
- plasma membranes fuse triggering fast block to polyspermy
- sperm nucleus enter and cortical reaction causes slow block to polyspermy
- fusion of sperm and egg nuclei form the diploid nucleus of the zygote
5
Q
What is cleavage?
A
the unicellular zygote divides to become multicellular while maintaining the same overall size
- rapid cell division with little growth of individual cells (minimal G1 and G2 phases)
6
Q
What are blastomeres?
A
the small cells resulting from cleavage
7
Q
What is a blastula?
A
a hollow ball of cells with a fluid-filled cavity called the blastocoel
8
Q
How can cells that possess the same genome look and behave differently?
A
- differential gene expression:
- cells express different genes depending on their location and the stage of development
- expressing different genes leads to the production of different proteins, which in turn determine the structure and behaviour of the cell at any given time
9
Q
How does a cell know what gene to express?
A
- cytoplasmic determinants: the signal comes from within the cell
- inductive signals: the signal comes from outside the cell
10
Q
How do cytoplasmic determinants express genes?
A
there are molecules within the cytoplasm that can be distributed differently to daughter cells to regulate gene expression differently
11
Q
How do inductive signals determine gene expression?
A
the signal molecules that a cell is exposed to depend on its location within the embryo, and the stage of development
12
Q
Why is preventing polyspermy important?
A
to ensure the zygote has the correct number of maternal and paternal DNA (chromosomes)
13
Q
True or false? A frog blastula is essentially the same size as the zygote from which is developed
A
True
14
Q
True or false? Every cell in a multicellular organism contains an identical genome
A
True
15
Q
Which mechanism is responsible for a muscle cell turning into a skin cell when moved to a new location?
A
induction
16
Q
What is morphogenesis?
A
the rearrangement of cells or sheets of cells in the embryo
- gastrulation: the stage when 3 germ layers are established, and the basic body plan is set up
- organogenesis: the formation of organs
17
Q
Gastrulation results in a 3-layered _____
A
gastrula
18
Q
What are the steps of gastrulation?
A
- cells in the vegetal hemisphere push inward
- outer cells (future mesoderm and endoderm) roll inward
- blastocoel collapses and a new cavity (archenteron) is formed
- cells at the animal pole (future ectoderm) spread over the outer surface
19
Q
What is convergent extension?
A
an example of cells changing their position (morphogenesis)
- produces a longer, narrower structure
20
Q
Explain the formation of the neural tube
A
microtubules and actin filaments change the shape of ectodermal cells causing them to curve into each other. This forms a circle of cells which breaks off from the other ectodermal cells
21
Q
What is an example of programmed cell death
A
apoptosis (cell death) removes the webbing between digits
22
Q
What are the two major systems that control responses to stimuli, coordinate body activities, and maintain homeostasis?
A
the nervous system and endocrine system
22
Q
Endocrine vs. nervous signaling
A
endocrine:
- uses hormones as signal
- transported through blood
- occurs quickly or slowly
- lasts for a short or long period of time
- specificity is achieved by hormone/receptor interaction
nervous:
- uses electrical impulses and chemical neurotransmitters
- transported through neurons
- occurs very rapidly
- duration is very short
- specificity is achieved by close connection of neurons and target cells
23
Q
What are the different functions of the endocrine and nervous systems?
A
the endocrine system is specialized for coordinating gradual changes that affect the entire body
the nervous system is specialized for directing immediate and rapid responses to the environment
24
What are neurons?
cells that are responsible for generating and transmitting the electrochemical impulses of the nervous system
25
What are glia?
cells that maintain homeostasis, form myelin, nourish, and provide support and protection for neurons in the central and peripheral nervous systems
26
How are signals transmitted through the nervous system?
- electrical impulses are triggered at the dendrites
- with sufficient stimulus (action potential), a new electrical impulse is generated and sent down the axon
- neurotransmitter is released and crosses the synapse to bind to receptors on the postsynaptic cell
27
What is the central nervous system made up of?
the brain and spinal cord
28
What is the peripheral nervous system made up of?
cranial nerves, ganglia (concentration of neuron cell bodies) outside CNS, spinal nerves (bundles of axons)
29
What are the three stages of information processing in the nervous system?
sensory input -> integration -> motor output
30
What do endocrine cells do?
they secrete hormones into the bloodstream that affect target cells to regulate physiology and behaviour
31
What are the major endocrine glands? (9)
- hypothalamus *
- pineal gland
- pituitary gland *
- thyroid gland
- parathyroid glands
- adrenal glands
- pancreas
- ovaries
- testes
32
What are the organs containing endocrine cells? (6)
- thymus
- heart
- liver
- stomach
- kidneys
- small intestine
33
What is the hypothalamus' role in the endocrine system and where is it located?
the hypothalamus is located in the brain and it acts as the master regulator of the endocrine system, primarily through the pituitary gland
34
What are the two components of the pituitary gland?
the anterior pituitary and the posterior pituitary
35
How does the posterior pituitary work?
it is made up of the axons of neurosecretory cells of the hypothalamus. neurosecretory cells are neurons that produce a hormone and secrete it directly into the bloodstream
36
How does the anterior pituitary work?
it is made up of endocrine cells that respond to hormones from the hypothalamus by secreting their own hormones
- hypothalamic hormones arrive via portal vessels
37
What are the 5 core concepts of biology that relate to animal development and physiology?
1. structure and function
2. evolution
3. systems
4. information flow
5. transformations of energy and matter
38
What are defining features of animals? (what makes an animal an animal?)
- develop into different stages of life
- heterotrophic
- need to move at one point in development
- respond to stimuli
- lack of cell walls
- multicellular
- possess regulatory genes called hox genes
39
What are hox genes?
they code for proteins in a particular way to create specific structures (i.e., proteins for anterior, proteins for trunk, etc.)
40
What functions do animals need to carry out?
- reproduce
- respire (gas exchange)
- maintaining internal functions (homeostasis)
- grow/develop
- bring in nutrients/ expel waste
- obtain energy and transport throughout body
- protect body from external harm
- support + movement of body parts
- obtain water and solute concentrations in internal environment
- coordination of body functions
41
What is the hierarchical organization of animal structure?
- molecules
- organelles
- cells
- tissues
- organs
- organ systems
- organisms
42
How is structure related to function?
- structure enables function
- a structure's physical and chemical characteristics influence its interactions with other structures, and therefore its function
43
What are functional trade-offs
when the specialization for one function limits the structure's ability to perform other functions
- it is impossible to optimize for all parameters
44
What is an example of a functional trade-off
two connective tissues:
cartilage- flexible, but not strong
bone- strong, but not flexible
45
How is function related to structure?
evolution: if the function works well, it improves fitness, which is passed on through genes and this keeps the structure intact
46
Biological ________ interact to form _______ _______
structures; complex systems
47
What are emergent properties?
emergent properties are the 'properties' that a higher level of organization exhibits but lower levels do not
(many components work together)
48
Do all cells need to exchange material with the external environment?
yes
49
What are the system(s) of the body that exchange material with the external environment?
- digestive
- excretory
- respiratory
- integumentary
50
What are the system(s) that transport material within the body?
circulatory + it interacts with all the systems that exchange externally
51
What are the two ways systems of animals are able to perceive and respond to changes in their internal and external environments?
through 1) chemical and 2) electrical signaling between cells that coordinate responses at the cellular, tissue, organ, and system levels
52
What is homeostasis?
the maintenance of a relatively stable internal environment
53
Does homeostasis rely on positive or negative feedback?
negative - we want to return our environment to what it originally was, not reinforce whatever is altering it
53
Why is homeostasis important?
cells are optimal under certain conditions (e.g., enzymes and membranes are sensitive to changes in surroundings)
53
Negative feedback vs. positive feedback
negative: control mechanism in which the response opposes the original stimulus
positive: control mechanism in which the response reinforces the original stimulus
54
Are uterine contractions during labor that cause more contractions an example of a (+/-) feedback? What about a high [CO2] triggering more rapid breathing?
positive; negative
55
Do animals ever change set points and normal ranges of physiological parameters?
yes, animals will undergo REGULATED changes for altering stages of life, cyclic events (menstrual cycle), and as a response to environmental change (acclimatization)
56
Where do animals get energy and what is the 'currency unit' they use for energy within their bodies?
food; ATP
57
Why do resource trade-offs occur?
organisms have limited energy and material resources so they must efficiently allocate across competing functional demands
- trade-off is where the energy will be used for best outcome
58
What kind of trade-off is this: the ability of skin to protect is limited by its need to exchange materials
functional
59
What kind of trade-off is this: animals that produce many offspring at once provide little care for those offspring
life-history
60
Why do animals eat?
all physiological functions require energy and/or matter
- food is how we get both
61
What is bioenergetics?
the overall flow and transformation of energy within an organism
IMPORTANT: not all molecules from food are used - some are lost in feces and nitrogenous waste
62
How much energy does an animal need?
- enough to maintain basic metabolic functions
- maintain cellular activity, blood flow, respiration, temperature
- the MORE ACTIVE an animal is, the MORE ENERGY is needed
63
Metabolic rate
amount of energy used per unit time (hour, day, etc.)
64
Basal metabolic rate (BMR)
metabolic rate of a NON-GROWING endotherm that is AT REST, has an EMPTY digestive tract, and is NOT experiencing stress (i.e., the min amount of energy to maintain basic functions)
65
How can an animal's energy use be measured?
- measure amount of food eaten and feces released
- heat production
- oxygen consumption
- CO2 production
66
What are the two types of BMR (think mouse and elephant)?
1. absolute/total amount
2. amount per unit body weight
67
What is the chemical energy from food used for?
used in cellular respiration to produce ATP or the energy is stored
68
What are organic molecules needed for?
biosynthesis (they are essentially building blocks)
69
What functions are carried out by the digestive system?
1. ingestion
2. digestion
3. absorption
4. elimination
70
What is the difference between mechanical digestion and chemical digestion?
mechanical digestion is done through chewing and muscle movements (churning), chemical digestion is done through the use of enzymes
BOTH occur in the mouth AND stomach
71
Why are structures related to ingestion the most diverse part of the digestive system?
the food an animal consumes is very diverse among animals
- animals have evolved structures that allow them to exploit these various food sources
72
What are the four main feeding mechanisms?
1. suspension and filter feeders
2. substrate feeders
3. fluid feeders
4. bulk feeders
73
What is peristalsis?
the wave-like movement of food from the mouth through the esophagus to the stomach
74
What is the purpose of sphincters?
to prevent food from going where it is not supposed to
- traveling back up the esophagus
- traveling to the small intestine before fully digested
75
What does saliva contain?
- mucus: protects lining of mouth and lubricates food
- buffers: help prevent tooth decay by neutralizing acid
- antimicrobial agents: kill bacteria
- salivary amylase: enzymatic breakdown of carbohydrates
76
What does the epiglottis do?
while swallowing food, the epiglottis covers the trachea to keep food from entering; after swallowing, it goes back up to allow air into the trachea
77
Explain the path of food once it enters an animal's mouth
1. teeth mechanically digest the food and enzymes in the saliva chemically digest to produce a bolus
2. the epiglottis closes off the trachea as the bolus passes down the throat and through the esophageal sphincter, which closes after food goes through it
3. the food travels down the rest of the esophagus and through the sphincter and into the stomach
4. food is further mechanically digested in the stomach by gastric juice to become chyme
5. absorption of nutrients occurs in the small intestine
6. small amounts of water is absorbed in the large intestine before waste is excreted from the anus
78
Why don't we digest ourselves?
the components of gastric juice remain inactive until they enter the lumen of the stomach; parietal cells separately release hydrogen and chlorine and chief cells release an inactive form of pepsin: pepsinogen; in addition, mucus cells line the stomach to protect
79
Is the conversion of pepsinogen to pepsin an example of negative feedback? Why or why not?
no, because it is reinforcing the production of more pepsin
80
Where are carbohydrates chemically digested?
- oral cavity, pharynx, esophagus
- small intestine: pancreatic enzymes, epithelial enzymes
81
Where are proteins digested?
- stomach
- small intestine: pancreatic enzymes, epithelial enzymes
82
Where are nucleic acids digested?
- small intestine: pancreatic and epithelial enzymes
83
Why do bile salts play a role in the digestion of lipids?
chyme is mostly water based and lipids are insoluble in water, which means they do not dissolve well. Digestion can only happen when molecules are broken down well, so bile salts emulsify lipids to break them down further
84
Where does the digestion of lipids happen and by what enzyme?
in the small intestine by pancreatic enzymes
85
Why is the structure of the small intestine well suited for absorption?
the small intestine is made of large circular folds which contain villi to increase surface area. On the surface of the villi are microvilli which increase surface area even more. Blood vessels are closely connected to the outside of the small intestine
86
What do lymph vessels do?
they carry lipids from the small intestine
87
Why is the liver important in the digestive system?
it regulates the distribution of nutrients to the rest of the body and functions in detoxification
88
What are the 3 parts of the large intestine?
- colon
- cecum
- rectum
89
How do the digestive tracts of carnivores and herbivores differ?
- the cecum is MUCH larger in herbivores as it ferments plant material
- overall, the digestive tract of herbivores is longer than that of carnivores
90
What does the colon do?
- responsible for some water reabsorption
- formation and elimination of feces
- feces: undigested material and bacteria
91
What triggers the secretion of digestive hormones?
the presence of food
92
What do digestive hormones trigger?
the secretion of gastric juices and digestive enzymes
93
How do insulin and glucagon regulate energy storage?
- insulin causes excess energy to be stored as glycogen in liver and muscle, then as fat in adipose cells
- glucagon is secreted during energy deficit and causes the breakdown of liver glycogen, then muscle glycogen and fat
94
How do hormones regulate appetite? What are leptin, insulin, peptide YY, and ghrelin?
a satiety center in the brain generates nerve impulses that make us feel hungry or full
- leptin: produced by adipose and regulates long-term appetite
- insulin and peptide YY are secreted after a meal
- ghrelin is secreted when stomach is empty
95
Diffusion is only ______ over ______ distances
rapid; short
96
Rate of diffusion is _________ proportional to distance
inversely
97
To maximize diffusion rate, exchange surfaces should have:
a large surface area and be thin
98
Do all cells in a multicellular organism need to exchange molecules with the environment?
yes
99
How do animals with many cell layers exchange molecules with the external environment?
by the use of a circulatory system
100
What are the 3 basic components of the circulatory system that all animals share?
1. a circulatory fluid
- blood in a closed system
- hemolymph in an open system
2. set of interconnecting vessels
3. a muscular pump
101
Explain the path of deoxygenated blood?
1. it return to the right atrium of the heart through two major veins: the superior and inferior vena cava
2. the right atrium contracts, pushing the blood into the right ventricle
3. the right ventricle contracts and pushes the blood into the pulmonary artery, sending it to the lungs where it is oxygenated
4. oxygenated blood returns to the heart via the pulmonary veins and enters the left atrium
5. the left atrium contracts, pushing the blood into the left ventricle
6. the left ventricle contracts, sending the blood into the aorta and throughout the body
102
Why are valves only in veins?
by the time blood is in the veins, the pressure at which it is being pushed back to the heart is very weak. Valves ensure that the blood does not flow backwards
103
Diastole vs. systole
diastole = relaxation
systole = contraction
104
Explain the cardiac cycle (diastole/systole)
1. atrial and ventricular diastole
2. atrial systole and ventricular diastole
3. ventricular systole and atrial diastole
105
How does blood vessel structure reflect function?
arteries have much thicker walls (endothelium, smooth muscle, connective tissue) while veins have thinner walls
veins have valves to prevent backflow as pressure is not strong enough to push it through to heart
106
What type of blood vessel has the greatest area? Highest velocity? Most pressure?
capillaries; arteries; arteries
velocity: slows in capillaries but increases a bit in veins (not as fast as arteries though)
pressure: arteries have systolic pressure and diastolic pressure
107
What regulates blood flow?
- nerve impulses
- hormones
- local chemicals that affect arteriole diameter and pre-capillary sphincters
108
Why do capillaries have thin walls and why does the blood travel through at such a slow velocity?
both characteristics allow for efficient exchange of materials between the blood and the interstitial fluid between the capillary and another cell
109
What is blood?
blood is a tissue made up of different cell types that are suspended in a liquid called plasma
110
What is plasma?
plasma is the fluid in which blood is suspended in:
- water
- ions
- proteins
- nutrients, metabolites, and wastes
111
What are the cellular components of blood?
- erythrocytes (red blood cells)
- lymphocytes (white blood cells)
- platelets
112
What makes respiratory surfaces so specialized for gas exchange?
they have very large surface areas and very thin exchange surfaces
ex: gills, tracheae, lungs
113
Why are gills unsuitable for terrestrial environments?
respiratory surfaces must be moist, therefore, terrestrial animals have an ENCLOSED respiratory surface to prevent excess water loss (gills are external)
114
What are the components of the mammalian respiratory system?
- nasal cavity (and mouth)
- pharynx
-larynx
- trachea
- lungs
- bronchus
- bronchioles
- terminal bronchiole
- alveoli
- diaphragm
- capillaries
- pulmonary vein and artery
115
How is hemoglobin important to the respiratory system?
red blood cells are packed with hemoglobin which binds with O2 that is respired. Then, the O2 can be transported throughout the body of larger, more complex animals
116
How many oxygen binding sites does hemoglobin have?
4
117
What is the difference between a temperature regulator and a temperature conformer?
a regulator will regulate their physiological parameters no matter the external temp while a conformer conforms to external conditions
118
Regulators use ______ mechanisms to control internal changes
homeostatic; this allows for small internal fluctuations even in the case of larger external fluctuations
119
What are the two physiological parameters being regulated in animals?
- thermoregulation
- osmoregulation
120
What is thermoregulation and why does it matter?
the maintenance of an internal temperature within a tolerable range
why:
-biochemical and physiological processes are sensitive to temp changes
- animal species have optimal internal temp ranges
121
What is a poikilotherm?
an animal who's body temperature varies with the environment
122
What is a homeotherm?
an animal that has a relatively stable body temperature
123
What is an endotherm?
an animal that relies on metabolism as their major heat SOURCE
124
What is an ectotherm?
an animal that relies mostly on their external environment as their major heat SOURCE - they do not produce enough heat on their own
125
Are all poikilotherms ectotherms? Are all homeotherms endotherms?
NO! It depends on habitat in some cases
126
What are the anatomical/physiological processes involved in thermoregulation?
- evaporative heat loss: water lost from moist surfaces cools, adaptations of this include panting and sweating
- circulatory adaptations: vasoregulation, countercurrent heat exchangers
- metabolic heat production: all metabolic activity produces heat, muscle contraction (activity, shivering), brown adipose tissue
- insulation: fur, feathers, fat
127
Explain countercurrent heat exchangers
heat is transferred between fluids flowing in opposite directions; heat from warm arterial blood is transferred to cooler venous blood as it returns to body core
128
Explain vasoregulation (thermoregulation)
- achieved through nerve impulses and hormones
- vasodilation (relaxation): allows more blood to flow from core to surface for cooling
- vasoconstriction (tensed): reduces blood flow from core to surface to prevent heat loss
129
What are some examples of behavioural responses involved in thermoregulation?
- shade seeking, sun-basking, migration
130
Water crosses cell membranes via...
simple diffusion and facilitated diffusion
131
What is osmoregulation?
the control of solute concentrations and the balance of water gain and loss from the body
132
What is a hyperosmotic solution?
a solution containing a higher solute concentration and lower free H2O concentration
133
What is a hypoosmotic solution?
a solution with a lower solute concentration and a higher free H2O concentration
134
What is osmosis?
the movement of water across a selectively permeable membrane
135
What is hyperosmotic fluid?
- higher [solutes] outside cell
- water leaves cell through osmosis
- cells that lose too much water shrivel and (may) die
136
What is hypoosmotic fluid?
- lower [solutes] outside cell; higher inside
- water enters cell through osmosis
- cells that gain too much water burst and die
137
What is isoosmotic fluid?
- same [solutes] inside and outsideof cell
- no net movement of water in or out of cells (water moves an equal amount in and out)
138
What are osmoconformers?
marine animals that are isoosmotic with their environment (no loss or gain of water)
- some have stable osmolarities while other tolerate variability
- actively transport specific solutes to maintain homeostasis
139
What are osmoregulators?
marine, freshwater, and terrestrial living animals that maintain a stable internal osmolarity
- particular internal osmolarity is achieved by actively transporting solutes into or out of cells
140
Explain osmoregulation in a marine fish. Are they hypoosmotic or hyperosmotic relative to the seawater?
they are hypoosmotic relative to seawater because seawater has a higher solute concentration
- osmotic water loss through gills + other parts of body surface (this loss of water increases internal osmolarity)
- gain of water and salt ions from food
- gain of water and salt ions from drinking seawater (marine fish drink seawater to replace water lost across body surfaces)
- excretion of salt ions from gills
- excretion of salt ions and small amounts of water in concentrated urine
141
Explain osmoregulation in a freshwater fish
freshwater fish = hyperosmotic relative to external water
- osmotic water gain through gills and other parts of body surface
- gain of water and some ions through food (freshwater fish drink almost no water)
- uptake of salty ions by gills
- excretion of salt ions and large amounts of water in dilute urine (freshwater fish take up salt ions and excrete water to bring internal osmolarity back up)
142
What are some adaptions to prevent water loss (dehydration) in terrestrial animals?
- body coverings: cuticle, shells, keratinized skin
- nocturnal
143
How do terrestrial animals prevent dehydration?
they maintain water balance by drinking and eating moist food and producing metabolic water through cellular respiration
144
How do transport epithelia help animals control solute concentrations of internal body fluids?
they are specialized for moving particular solutes in controlled amounts in specific directions
145
Explain transport epithelia in more detail
- they have large surface areas
- some face the external environment directly (gills), most line tubular networks that connect to the outside by an opening on the body surface (salt glands, kidneys)
- closely connected to circulatory fluid
146
How do seabirds, sea turtles, and marine iguanas remove excess salt?
through salt-excreting glands
147
What is innate immunity?
the recognition of traits shared by broad ranges of pathogens, using a small set of receptors; all animals have it; rapid response
148
What is adaptive immunity?
the recognition of traits specific to particular pathogens, using a vast array of receptors; vertebrates only; slower response
149
What are the three lines of defense in immunity?
1. barrier defenses: skin, mucous membranes, secretions
2. internal defenses: phagocytotic cells, natural killer cells, antimicrobial proteins, inflammatory response
3. humoral response: antibodies defend against infection in body fluids
OR
3. cell-mediated response: cytotoxic cells defend against infection in body cells
150
What do barrier defenses do and what are they?
they prevent most pathogens from entering the body
- skin/shells/cuticle: thickened outer surface inhibits entry of pathogens
- mucous membranes: mucus secreted by internalized external surfaces traps microbes and other particles
- secretions (saliva, tears): washing action prevents microbial colonization, hostile chemical environment: lysozyme and acidic pH
151
How do phagocytotic cells know what's a pathogen and what isn't?
they recognize molecules that are characteristic of a set of pathogens; the recognized molecule must be absent from the vertebrate itself but essential to the survival of the pathogen (i.e., pathogen should not survive w/o molecule)
152
How do phagocytotic cells help defend against pathogens?
they destroy the pathogens through phagocytosis: engulfing the pathogen in a vacuole and digesting it with enzymes in a lysosome, then excreting the waste from the pathogen
153
Where are phagocytotic cells located?
- blood
- skin
- mucous membranes
- lymph
154
What is the purpose of the lymphatic system?
to collect leaked fluid from an injury (open wound) and eliminate any pathogens that could be in it (i.e., they filter the leaked fluid)
155
How do natural killer cells protect against pathogens?
natural killer cells are a part of the internal defense and they work by recognizing surface proteins of virus-infected or cancerous cells; once they have recognized one of these cells, they release chemicals that cause apoptosis in these cells
156
How do antimicrobial proteins work and what are two examples?
they attack pathogens or impede their reproduction
ex: interferons: secreted by virus-infected cells, trigger surrounding cells to produce chemicals that inhibit viral reproduction
ex: complement proteins: plasma proteins that are activated by substances on the surface of many microbes, lead to lysis of invading cells, also involved in inflammation and adaptive immunity
157
What is lysis? (immunity)
the breakdown of a cell by damaging its plasma membrane
158
What is the inflammatory response and what are the two examples given?
signaling molecules are released by injured or infected (flu) tissue and they cause local inflammation (e.g., sore throat)
ex: histamine- triggers vasodilation and increased blood vessel permeability in affected area, more white blood cells and proteins can enter interstitial fluid
ex: cytokines- further increase blood flow to the affected area
159
Explain the role of signaling molecules in the inflammatory response including what happens after what they do
they cause capillaries to dilate and increase blood flow, as a result, the phagocytotic cells (neutrophils), activated complement proteins, and other microbial proteins arrive from the blood and work together to fight the infection
160
What is a systematic inflammatory response?
it is an exaggerated response to a more serious infection
- releases more white blood cells from the bone marrow
- reset body's thermostat to cause fever
161
Histamines increase local blood flow, which leads to the arrival of blood cells that release cytokines that promote local blood flow. This is an example of what kind of feedback? (+/-)?
positive because it is reinforcing blood flow
162
How is specificity achieved in adaptive immunity?
through interactions between antigens and antigen receptors
163
What is an antigen and what is an antigen receptor?
an antigen is a large molecule found on the surface of specific pathogen or secreted by that pathogen (there are many)
an antigen receptor is a protein produced by B or T cells and it recognizes a specific antigen (like lock and key)
164
What is an epitope?
it is a small, accessible portion of an antigen that binds to an antigen receptor (antigens have many epitopes)
165
An immune system that is able to recognize multiple epitopes of a single antigen molecule is advantageous because?
it is less likely that multiple epitopes will mutate than it is that one epitope will mutate
166
B cells and T cells are what type of blood cell?
lymphocytes
167
Where do B and T cells mature?
B cells: in the bone marrow
T cells: migrate to the thymus (from the bone marrow) and mature there
168
How many types of antigen receptors does a single B or T cell produce?
only one
169
How many epitopes can each antigen receptor bind to?
only one
170
What produces the specificity of antigen-binding sites?
variable regions of the antigen receptors
171
What is the humoral response?
B cell antigen receptors bind to intact antigens in the blood or lymph
- antigens may be on the surface of the pathogen or secreted by the pathogen
172
What is the cell-mediated response?
T cell antigen receptors can only bind to antigen FRAGMENTS that are presented on the surface of the HOST cells (not the pathogen itself)
173
What is proliferation? Why do B and T cells do it?
proliferation is the production of many more B and/or T cells when they encounter their epitope because there are many more viruses to attack
B and T cells proliferate into two types of cells: effector cells and memory cells
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What are effector cells?
short-lived cells that take effect immediately against a pathogen or its antigen
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What are memory cells?
long-lived cells that give rise to effector cells if the same epitope is encountered again
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What is the effector form of B cells?
plasma cells that secrete antibodies
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What are antibodies?
soluble forms of the antigen receptor; they are specific for the same epitope as the og B cell
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What do anitbodies do?
they mark pathogens for inactivation and destruction:
- neutralization prevents pathogen entry into cells
- antibody binding increases the ability of phagocytotic cells to recognize the pathogens
- leads to increased phagocytosis of pathogens
- antibodies activate the complement system (complement proteins) which leads to pore formation (for lysis)
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What are the two effector forms of T cells?
helper T cells and cytotoxic T cells
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How do helper T cells work?
help to activate B cells and cytotoxic T cells by releasing cytokines
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What do cytotoxic T cells do?
they secrete proteins that lead to cell death in infected cells; they bind to infected cells and release perforin and granzymes
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What does perforin do?
it causes pores to form in the cell membrane of infected cells, allowing fluids to enter
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What do granzymes do?
they initiate apoptosis
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Explain memory cells
they are responsible for long-term protection provided by a prior infection or vaccination
- they give rise to effector cells only if the epitope is encountered again
- secondary immune response -> rapid
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What is a hydrostatic skeleton?
fluid held under pressure in a closed body compartment
ex: worms, jellyfish, sea anemone
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What is an endoskeleton?
hardened internal skeleton
ex: sponges, echinoderms, chordates
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What is an exoskeleton?
hardened external skeleton
ex: mollusc shells, arthropod cuticles
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How do animals with a hydroskeleton locomote?
squeeze -> elongate
through a peristaltic motion:
ex: earthworms have longitudinal muscle and circular muscle
- when the longitudinal muscle is relaxed and the circular muscle is contracted, that portion of their body elongates
- when the longitudinal muscle is contracted and the circular muscle is relaxed, that portion of their body is shortened
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How do endoskeletons and exoskeletons generate movement?
by using muscles attached to the hard parts of a skeleton
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What are antagonistic muscles?
muscles that generate opposite movements across a joint
when one is contracted, the other is relaxed
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Flexor vs. extensor muscles
a flexor muscle (ex: biceps) brings the joint together when contracted while an extensor muscle (triceps) opens the joint when contracted
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What is the hierarchical organization of vertebrate muscle?
- skeletal muscle
is composed of
- muscle fibers (multinucleated cells)
are composed of
- myofibrils (tube-long organelles)
are composed of
- thin (actin) and thick (myosin) filaments
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What is a sarcomere?
a functional unit of muscle composed of multiple thick and thin filaments bounded by Z lines
(where contractions happen)
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What is the thin filament of muscle? The thick filament?
thin: two chains of actin molecules
thick: multiple myosin molecules with their heads exposed
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Why is skeletal muscle also called striated muscle?
because of its striated appearance do to the strands of thick and thin filaments
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Do the filaments change their shape when the muscle contracts?
no, they slide past each other
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How do muscle contractions happen?
- first, a contraction is initiated by motor neurons which results in an increase in free Ca2+ in the myofibrils of muscle cells
- the Ca2+ interacts with tropomyosin and troponin to expose the myosin binding site on actin molecules
- for myosin to bind, it requires ATP to increase its energy configuration
- once bonded, ATP breaks down into ADP + P and the myosin head is now in high energy configuration
- the P molecule breaks off allowing for myosin to bind to the binding site on actin forming a cross-bridge
- the myosin head pulls the actin filament towards the M line in the center of the sarcomere, causing overlapping
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What do tropomyosin and troponin do?
Tropomyosin covers the binding sites on actin, preventing myosin heads from attaching
Troponin complexes are binding sites for Ca2+ and once Ca2+ binds, the complex alters the shape of tropomyosin, exposing the myosin-binding sites
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What would happen if a muscle was injected with a drug that degrades tropomyosin?
the muscle would contract, but ONLY when ATP is available
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Locomotion is ______ ______ from place to place
active travel
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How do animals move (think ATP)?
they must expend energy to overcome gravity (land) and friction (water)
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How do adaptions aid in locomotion?
natural selection favours adaptations that reduce energy costs
e.g., fusiform body shape, springy tendons
behavioural: passive descent in diving mammals
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How do land animals oppose gravity?
with powerful muscles and strong skeletal support to propel themselves and remain upright
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How do land animals maintain balance?
walking: bipedal animals keep one leg on ground; multi-legged animals keep three legs on ground
running/ jumping: all legs can leave the ground, momentum keeps the body upright
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How do tendons reduce energy expenditure?
when they stretch, they store energy in elastic fibres; the energy is then released to help in the next jump
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How do flying animals oppose gravity?
they must generate enough lift to overcome the downward force from gravity; they also tend to have low body mass and a fusiform body to help reduce drag
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How do animals living in water oppose friction?
most aquatic animals are fairly buoyant (i.e., overcoming gravity requires little energy)
however, water is very dense compared to air so drag IS a problem; fusiform body shapes reduce drag
