Animal biology Flashcards
1
Q
Fertilization
A
Forms the diploid zygote
2
Q
Embryonic stages
A
- Cleavage converts the unicellular zygote into a multicellular embryo
- Blastula, a hollow ball of cells
- Gastrulation where 3 germ layers are formed
3
Q
Differential gene expression
A
The foundation of the diverse cell type and behaviors seen throughout development
4
Q
Morphogenesis
A
Occurs via changes in cell position, shape, survival, and forms organs
5
Q
Model organisms
A
- Easy to study but broadly representative
- Developmental genes and mechanisms are very similar across animal species (ex. fruit flies and humans have similar genes with similar functions)
- Studying development in model organisms provides knowledge about development in general (ex. sea urchins, frogs)
6
Q
Fertilization in sea urchins
A
- External fertilization, release their sperm into the water, can be viewed externally
- Sperm and egg are haploid gametes
- Acrosome contains digestive enzymes, to digest the jelly coat around the egg
- Contact of sperm with jelly coat triggers the acrosomal reaction
- Surface proteins on acrosomal process bind to receptors on the egg cell membrane
- Plasma membranes fuse triggering fast block of polyspermy (depolarization from membrane)
- Sperm nucleus enters and cortical reaction causes slow block to polyspermy
- Fusion of sperm and egg nuclei form diploid nucleus and the zygote
- Egg cytoplasm contains many proteins and mRNA involved in early development
7
Q
Blastula
A
- In frogs, the zygote becomes a blastula
0 The blastula is a hollow ball of cells with a fluid filled cavity called the blastocoel
8
Q
Cleavage
A
- The process by which the zygote becomes multicellular
- Rapid cell division and little growth of individual cells (G1 and G2 phases skipped)
- Results in many smaller cells called blastomeres
9
Q
Differential gene expression
A
- 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 behavior of the cell at any given time
10
Q
How does the cell know what genes to express at any given time?
A
Two mechanisms:
1. Cytoplasmic determinants
- the signal comes from within the cell
2. Inductive signals
- the signal comes from outside the cell
11
Q
Cytoplasmic determinants
A
- Molecules within the cytoplasm that regulate gene expression
- Can be differentially distributed to daughter cells resulting in differences in genes expression
12
Q
Inductive signals
A
- The signal molecules that a cell is exposed to depend on its location within the embryo, and the stages of development
13
Q
Morphogenesis
A
- The rearrangement of cells or sheets of cells in the embryo
- Gastrulation: the stage when three germs layers are established, and the basic body plan is set up
- Organogenesis: the formation of organs (ex. neurulation = formation of the nervous system)
14
Q
Gastrulation
A
- Results in a three-layered gastrula
- Ectoderm, mesoderm, endoderm
15
Q
Gastrulation steps
A
- Cells in the vegetal hemisphere push inward (form the blastopore and blastocoel)
- Outer cells (future endoderm and mesoderm) roll inward
- Blastocoel collapses and a new cavity - archenteron is formed
- Cells at the animal pole (future ectoderm) spread over the outer surface
ectodermal and endodermal cells express different genes
16
Q
How is morphogenesis achieved
A
- Morphogenesis is achieved through changes in cell position, shape, and survival
- Convergent extension - example of cells changing position
- Produces longer, narrower structure
17
Q
Formation of the neural tube
A
- Ectodermal cells change shape during neural tube formation
- Ectoderm, neural plate, microtubules, actin filaments
18
Q
Programmed cell death
A
- Also shapes embryos
- Cells undergo apoptosis (programmed cell death)
- Ex. removal of webbing between digits
19
Q
Endocrine and nervous system
A
Endocrine and nervous systems are the major systems that control responses to stimuli and coordinate body activities and maintain homeostasis!
20
Q
Endocrine vs nervous speed
A
- Endocrine system is specialized for coordinating gradual changes that affect the entire body
- e.g. growth and development, reproduction, metabolic processes, and digestion
- Nervous system is specialized for directing immediate and rapid responses to the environment
- e.g. rapid locomotion and behaviors
21
Q
Neurons and glia
A
Neurons: cells responsible for generating and transmitting the electrochemical impulses of the nervous system
- Glia: cells that maintain homeostasis, form myelin, nourish, and provide support and protection for neurons in the central and peripheral nervous system
22
Q
Neural transmission
A
- Electrical impulses are triggered at the dendrites
- With sufficient stimulus to the cell body, 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
23
Q
Central nervous system (CNS)
A
- Brain
- Spinal cord
24
Q
Peripheral nervous system (PNS)
A
- Cranial nerves
- Ganglia outside CNS
- Spinal nerves
25
Q
Information processing
A
- Sensory input (sensor)
through peripheral (sensory neuron) - Integration (CNS)
through peripheral (motor neuron) - Motor output (effector)
26
Q
Endocrine cells
A
Secrete hormones into the bloodstream, affecting target cells to regulate physiology and behavior
27
Q
Hypothalamus
A
A brain region that acts as the “master regulator” of the endocrine system, primarily through the pituitary gland
28
Q
Posterior pituitary
A
- Made up of axons of neurosecretory cells of the hypothalamus
29
Q
Bioenergetics
A
The overall flow and transformation of energy within an organism
30
Q
How much energy does an animal need?
A
- Enough to maintain basic metabolic functions
- the more active an animal is, the more energy needed
31
Q
Metabolic rate
A
- MR: the amount of energy used per unit of time
- Basal metabolic rate (BMR) is the 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)
32
Q
How to measure an animal’s energy use?
A
- Measure o2 consumption
- Measure co2 production
- Measure the amount of food being eaten
- Faeces
33
Q
Energy, organic molecules, essential nutrients
A
- Chemical energy in food is used in cellular respiration to produce ATP or is stored
- Organic molecules are needed for biosynthesis
(e.g., nucleic acids, carbohydrates, proteins, and lipids) - Essential nutrients
- e.g. Essential amino acids, essential fatty acids, vitamins, and minerals
34
Q
The four stages of food processing
A
- Ingestion
- Digestion
- Absorption
- Elimination
35
Q
Ingestion
A
- Structures associated with ingestion are the most diverse part of the digestive system
- Mammalian teeth reflect diet
36
Q
Four main feeding mechanisms
A
- Suspension feeders and filter feeders (e.g. whale)
- Substrate feeders (e.g. caterpillar)
- Fluid feeders (e.g. mosquito)
- Bulk feeders (e.g. snake)
37
Q
Digestive system parts
A
- Alimentary canal + accessory organs
- Specialized in sequential stages of food processing
- Food pushed along by peristalsis
- Sphincters between compartments
38
Q
Oral cavity
A
- The Oral cavity is the first site of mechanical and chemical digestion
- Salivary glands produce saliva
- Saliva contains:
- Mucus (protects the lining of the mouth and lubricates food)
- Buffers (help prevent tooth decay by neutralizing acid)
- Antimicrobial agents (e.g., lysozymes)
- Salivary amylase (Enzymatic breakdown of carbohydrates)
39
Q
Stomach
A
- Epithelium secretes gastric juice
- Food mechanically mixed with gastric juice to become chyme
40
Q
Gastric glands 3 specialized types of cells
A
- Mucous cells
- Chief cells (make pepsinogen)
- Parietal cells (secrete hcl (gastric acid))
41
Q
Location of chemical digestion
A
- Oral cavity, pharynx, esophagus: carbs
- Stomach: proteins
- Small intestine: Pancreatic enzymes: carbs, protein, nucleic acid, lipids
- Small intestine: epithelial cells: carbs, protein, nucleic acids
42
Q
Lipid digestion
A
- Liver produces bile
- Gall bladder stores bile
- Bile released into the small intestine emulsifies fats
- Bile breaks it into smaller pieces
- Digested by pancreatic enzymes
43
Q
How do we not digest ourselves?
A
- Mucus provides protection for cells lining alimentary canal
- HCl and digestive enzymes maintained in inactive forms until released to alimentary canal lumen
- Rapid turnover of cells lining alimentary canal
44
Q
Liver
A
- Produces bile
- Regulates distribution of nutrients to rest of body
45
Q
Structure of the small intestine (well suited for digestion and absorption)
A
- The small intestine has an incredibly large surface area
- Long narrow tube
- Large circular folds
- Villi
- Microvilli
- The many blood vessels connecting with the small intestine carry material to the liver
- The liver regulates the distribution of nutrients to the rest of the body, and functions in detoxification
- Acts like a “guard post” between what you ingest and the rest of your body
46
Q
Temperature Regulation vs Conformity
A
Animals either regulate their physiological parameters OR allow their bodies to conform to external conditions
47
Q
Regulators
A
Regulators use homeostatic mechanisms to control internal changes
48
Q
Conformers
A
Conformers allow their internal condition to change in response to external change
- May be able to tolerate greater ranges for physiological parameters
- Internal stability is possible in stable environments
49
Q
Physiological parameters being regulated
A
- Thermoregulation (temperature)
- Osmoregulation (body water, and solute concentration)
50
Q
Thermoregulation
A
The maintenance of an internal temperature within a tolerable range
51
Q
Why does body temp matter?
A
Biochemical and physiological processes are sensitive to changes in temp
ex:
- enzyme reaction rates
- proteins can denature when temp too high
- membrane fluidity can vary with temperature
52
Q
Thermal strategies
A
- Can be defined based on the source of heat
- Endotherms vs Ectotherms
53
Q
Ectotherms
A
Rely primarily on external environment as their major heat source
54
Q
Homeotherms vs poikilotherm
A
- Body temp of poikilotherms varies with the environment
- Homeotherms have relatively constant body temperature
55
Q
Endotherms
A
Endotherms rely on metabolism as their major heat source
56
Q
Thermoregulation
A
Thermoregulation requires maintaining equal rates of heat gain and heat loss
57
Q
Heat loss/gain anatomical/physiological processes
A
- Evaporative heat loss
- Circulatory adaptations
- Metabolic heat production
- Insulation
58
Q
Circulatory adptations
A
- Countercurrent heat exchangers: found in birds and mammals
- Vasoregulation: common to endotherms and ectoderms
59
Q
Vasoregulation
A
- Vasoregulation is achieved via nerve impulses and hormones
- Vasodilation relaxes smooth muscle walls of surface blood vessels
- (Allows more blood flow from core to surface for cooling)
- Vasoconstriction tenses smooth muscle walls of surface blood vessels
- (reduces blood flow from core to surface to prevent heat loss)
60
Q
Countercurrent heat exchanges
A
- Heat is transferred between fluids flowing in opposite directions
- Heat from warm arterial blood is transferred to cooler venous blood as it returns to the body core
61
Q
Metabolic heat production
A
- All metabolic activity produces heat
- Endotherms have much higher metabolic rates than similarly sized ectotherms
- Muscle contraction: activity, shivering
- Brown adipose tissue (some mammals):
- High concentration of mitochondria
- Cellular respiration produces heat instead of ATP
62
Q
Insulation
A
- Fur, feathers, fat
- Major adaptation to prevent heat loss in mammals and birds
63
Q
Behavioral thermoregulation
A
- Shade seeking/sun basking, migration
64
Q
Blubber
A
- A thick layer of vascularized adipose tissue under the skin of all cetaceans, pinnipeds, penguins, and sirenians
- Fewer blood vessels than human skin
65
Q
Osmoregulation
A
- The control of solute concentration and the balance of water gain and loss from the body
- Physiological parameters
- Body water (volume): e.g. blood, interstitial fluid, within cells
- Total solute concentration: e.g. calcium, potassium, urea, certain amino acids, water-soluble hormones
- Individual solute concentrations, calcium vs urea … etc.
66
Q
Osmosis
A
- The movement of water across a selectively permeable membrane
67
Q
Hyperosmotic vs Hypoosmotic
A
- Hyperosmotic
- Higher solute concentration
- Lower free H2O concentration - Hypoosmotic solution:
- Lower solute concentration
- higher free H2O concentration
68
Q
Osmolarity
A
- Hyperosmotic fluid:
- Higher (solutes) outside cell
- Water leaves cells through osmosis
- Cells that lose too much water shrivel and (may) die - Hypoosmotic fluid:
- Lower (solutes) outside cell; (higher (S) inside)
- Water enters cells through osmosis
- Cells that gain too much water burst and die - Isoosmotic fluid:
- Same (solutes) inside and outside cell; (i.e., balanced)
- No net movement of water into or out of cells
69
Q
Osmoconformers
A
- Isoosmotic with their environment
- No tendency to gain or lose water
- All are marine
- Some have stable osmolarities while others tolerate variable osmolarities
- actively transport specific solutes to maintain homeostasis
70
Q
Osmoregulators
A
- Maintain a stable internal osmolarity
- Found in marine, freshwater and terrestrial environments
- A particular internal osmolarity is achieved by actively transporting solutes into or out of cells
- Water then flows in response to osmotic gradients
71
Q
Osmoregulation energy
A
- Energy costs are reduced by minimizing osmotic differences between body fluids and the surrounding environment
- e.g. freshwater molluscs have lower internal osmolarities than do marine molluscs
72
Q
Osmotic challenge and environment for osmoregulators
A
- Freshwater osmoregulators: gain water
- Marine osmoregulators: lose water
- Terrestrial animals: lose water
73
Q
Adaptations to reduce water loss in terrestrial animals
A
- Body coverings: cuticle, shells, keratinized skin
- Nocturnal
- Maintain water balance by drinking and eating moist food and producing metabolic water through cellular respiration
74
Q
How do animals control the solute concentration of an internal body fluid
A
- Transport epithelia
- One or more layers of epithelial cells specialized for moving particular solutes and controlled amounts in specific directions
75
Q
Transport epithelia traits
A
- Large SA
- Some face the external environment directly (e.g. gills)
- Many line tubular networks that connect to the outside by an opening on the body surface
- Transport epithelia are closely connected to circulatory fluid
76
Q
Innate immunity
A
- All animals
- Recognition of traits shared by broad ranges of pathogens, using a small set of receptors
- Rapid response
77
Q
Innate immunity defenses
A
- Barrier defenses:
- Skin
- Mucous membranes
- Secretions - Internal defenses
- Phagocytic cells
- Natural killer cells
- Antimicrobial proteins
- Inflammatory response
77
Q
Adaptive Immunity
A
- Vertebrates only
- Recognition of traits specific to particular pathogens, using a vast array of receptors
- Slower response
78
Q
Adaptive immunity responses
A
- Humoral response:
- Antibodies defend against infection in body fluids
- Cytotoxic cells defend against infection in body cells
79
Q
Barrier defenses
A
- Prevent most pathogens from entering the body
1. Skin/shells/cuticle - Thickened outer surface inhibits entry by pathogens
2. Mucous membranes - Mucus secreted by internalized external surfaces traps microbes and other particles
3. Secretions - saliva, tears - Washing action prevents microbial colonization
- Hostile chemical environment: lysozyme, acidic pH
80
Q
Internal Defense: Phagocytotic cells
A
- Recognize molecules characteristic of a set of pathogens
- That recognized molecule is absent from vertebrates and is an essential component of certain groups of pathogens
- Destroy pathogens by phagocytosis
- Located in: Blood, skin, mucus membranes, lymph
81
Q
Internal defense: Natural killer cells
A
- Recognize surface proteins of virus - infected or cancerous cells
- Release chemicals that cause apoptosis (cell death) in infected or cancerous cells
82
Q
Internal defense: Antimicrobial proteins
A
- Attack pathogens or impede their reproduction
1. E.g. Interferons: - Are secreted by virus-infected cells
- Trigger surrounding cells to produce chemicals that inhibit viral reproduction
2. E.g. complement proteins - Are plasma proteins activated by substances on the surface of many microbes
- Lead to lysis of invading cells
- Also involved in inflammation and in adaptive immunity
83
Q
Internal defense: Inflammatory response
A
- Signaling molecules released by injured or (flu) infected cause local inflammation
1. E.g., Histamine - Triggers vasodilation and increased blood vessel permeability in affected area
- More white blood cells and proteins can enter interstitial fluid
2. E.g., Cytokines - Further increase blood flow to the affected
84
Q
Adaptive immunity
A
- Involves pathogen-specific recognition
- Specificity is achieved through interactions between antigen and antigen receptors
- Antigens are large molecules found on the surface of specific pathogens or secreted by those pathogens
- Antigen receptors are proteins produced by B cells or T cells
85
Q
Epitopes
A
- Antigens contain multiple epitopes
- An epitope is a small, accessible portion of an antigen that binds to an antigen receptor
86
Q
B cells and T cells
A
- Proliferate when they encounter their specific epitope
- Memory cells: Long-lived cells that give rise to effector cells if the same epitope is encountered again
- Effector cells: Short-lived cells that take effect immediately against the pathogen or antigen
87
Q
Lymphocytes
A
- Lymphocytes are white blood cells; produced in the bone marrow
- B cells mature in the bone marrow
- T cells migrate to the thymus for maturation
- each B or T cell produces a single type of antigen receptor
- Each antigen receptor binds to a single epitope of a single antigen
88
Q
Antigen receptors
A
- Variable regions of antigen receptors produce the specificity of the antigen binding site
89
Q
Humoral Response
A
- B cell antigen receptors bind to intact antigens in the blood or lymph
- These antigens may be on the surface of pathogens or may be free antigens secreted by pathogens
90
Q
Cell mediated response
A
- T cell antigen receptors can only bond to antigen fragments presented on the surface of host cells
91
Q
Effector forms of B cells
A
- Effector forms of B cells are plasma cells, which secrete antibodies
- Antibodies are soluble forms of the antigen receptor; specific for the same epitope as the original B cell
92
Q
Antibodies
A
- Antibodies mark pathogens for inactivation or destruction
- Neutralization prevents pathogen entry into cells
- Toxins can also be neutralized by antibodies
93
Q
Antibody marking
A
- Antibody binding increases the ability of phagocytic cells to recognize the pathogens
- Leads to increased phagocytosis of pathogens
- Antibodies activate complementary system, leading to pore formation
94
Q
Effector forms of T cells
A
- Effector forms of T cells are helper T cells and cytotoxic T cells
- Cytokines from helper T cells help activate B cells and cytotoxic T cells
- Helper T cells help activate B cells and cytotoxic T cells
- Cytotoxic T cells secrete proteins that lead to cell death in infected cells
95
Q
Cytotoxic T cells
A
- Cytotoxic T cells bind to infected cells and secrete perforin and granzymes
- Perforin causes pores to form on the cell membrane of infected cells
- Granzymes initiate apoptosis
96
Q
Memory cells
A
- Memory cells are responsible for long-term protection provided by a prior infection of vaccination
- Memory cells, produced during the original B cell or T cell proliferation, give rise to effector cells if the same epitope is encountered again
- (secondary immune response: rapid)
97
Q
Parts of the large intestine
A
- Colon, cecum, and rectum
- The cecum functions in fermenting ingested plant material
98
Q
Circulatory system
A
- Each cell in a multicellular organism must exchange molecules with the environment
- Animals with many cell layers require a circulatory system to transport materials between all the body cells and the organs that exchange those materials with the environment
99
Q
Three basic components of circulatory systems
A
- A circulatory fluid
- Blood in a closed circulatory system
- Hemolymph in an open circulatory system - Set of interconnecting vessels
- A muscular pump
100
Q
Two types of circulatory system
A
- Open circulatory system
- Hemolymph in sinuses surrounding organs - Closed circulatory system
- Small branch vessels in each organ
- Heart, blood interstitial fluid
101
Q
Double circulation
A
- Two circuits of flow to and from the heart
- Oxygenated and deoxygenated blood do not mix within the heart
102
Q
Flow of the heart
A
- Deoxygenated blood returning from the systemic circuit enters via the superior vena cava
- Right atrium
- When the right atrium contracts, blood is rushed into the right ventricle
- When the right ventricle contracts, blood is pushed into the pulmonary artery sending it to the lungs
- Oxygenated blood returning from the pulmonary circuit enters via the pulmonary veins
- It flows into the left atrium
- When the left atrium contracts, blood is pushed into the left ventricle
103
Q
Valves
A
- Valves ensure unidirectional flow of blood through the heart by closing to prevent backflow
1. Atrioventricular (AV) valves - Separate the atria from the ventricles and prevent backflow into atria when the atria relax
- Semilunar valves
- Separate ventricles from the arteries and prevent backflow into the ventricles when the ventricles relax
104
Q
The Cardiac Cycle
A
- Diastole: relaxation
- Systole: contraction
1. Atrial and ventricular diastole
2. Atrial systole and ventricular diastole
3. Ventricular systole and atrial diastole
105
Q
Blood flow regulation
A
- Blood flow is regulated by nerve impulses, hormones, and local chemicals that affect arteriole diameter and pre-capillary sphincters
- At any one time, only about 5-10% of the body’s capillaries have blood flowing through them
106
Q
Blood and interstitial fluid
A
- Thin capillary walls and slow velocity allow for exchange of materials between blood and interstitial fluid
107
Q
Hydrostatic skeleton
A
Fluid held under pressure in a closed body compartment
(e.g. worms, jellyfish, sea anemone)
108
Q
Endoskeleton
A
Hardened internal skeleton (e.g. sponges, echinoderms, chordates)
109
Q
Exoskeleton
A
Hardened external skeleton (e.g. mollusc shells, arthropod cuticles)
110
Q
Movement
A
Endoskeletons and exoskeletons generate movement using muscles attached to the hard parts of a skeleton
111
Q
Human arm movement
A
Bend/flex: Biceps contract, triceps relax
Extension: Triceps contract, biceps relax
biceps and triceps are antagonistic muscles, generate opposite movement across a joint
112
Q
Skeletal muscle parts
A
composed of..
- Muscle fibres (AKA multinucleated cells)
composed of..
- Myofibrils
composed of..
- thin (actin) and thick (myosin) filaments
113
Q
Sarcomere
A
- Functional unit of muscle, where movement happens
- A sarcomere is composed of multiple thick and thin filaments bounded by Z lines
114
Q
Myofibrils
A
- Composed of thin (actin) and thick (myosin) filaments
- Thin filament: Two chains of actin molecules
- Thick filament: Multiple myosin molecules with their head exposed
115
Q
Sarcomere contraction
A
- Sarcomere starts wide when relaxed
- Actin filaments get pulled in toward the center by myosin heads
- Thin and thick filaments are completely overlapped when fully contracted
- Thin and thick filaments do not change their length; they slide past each other
116
Q
How does the muscle know when to contract?
A
- Skeletal muscle contraction is initiated by motor neurons
- Results in an increase in free Ca2+ in myofibrils of muscle cells
- Ca2+ interacts with thin filament regulatory proteins (tropomyosin and troponin), exposes myosin binding site, allows myosin binding
117
Q
Locomotion
A
- Active travel from place to place
- To move, an animal must expend energy to overcome gravity and friction
- The animal’s environment determines which of these forces is the dominant force opposing locomotion
- Land and Air: Gravity
- Water: Friction
118
Q
Adaptations: locomotion
A
- Natural selection favours adaptations that reduce energy costs of locomotion
- Adaptations are usually anatomical
- e.g. fusiform body shape, springy tendons
- Adaptations can also be behavioural
- e.g. passive descent in diving mammals
119
Q
Land locomotion
A
- Gravity is the dominant force opposing locomotion on land
- Animals that locomote on land require powerful muscles and strong skeletal support to propel themselves and remain upright
120
Q
Maintaining balance
A
- When walking, bipedal animals keep one leg on the ground; multi-legged animals keep three legs on the ground
- When running or hopping, all legs can leave the ground; momentum keeps the body upright
121
Q
Reduce energy expenditure
A
- When tendons stretch as the animal lands, they store energy in the elastic fibers
- The energy is released to aid the next jump
122
Q
Locomotion in air
A
- Gravity is the dominant force opposing locomotion in air
- Wings of flying animals must generate enough lift to overcome gravity’s downward force
- Flying animals tend to have low body mass
(e.g. no urinary bladder, no teeth, hollow air-filled regions in bones - A fusiform body helps reduce drag (AKA friction)
123
Q
Locomotion in water
A
- Friction is the dominant force opposing locomotion in water
- Most aquatic animals are reasonably buoyant; i.e., overcoming gravity requires little energy
- But water is a denser and more viscous medium than air; drag (AKA friction) is a problem
- Fusiform body is an adaptation to reduce drag
124
Q
Capillary structure
A
- Increased branching increases area: capillaries have greater area than arteries and veins
- Same volume of fluid flows more slowly through a greater area: velocity is slowest within the capillaries
- The increase in area in the capillaries causes pressure to drop off. Blood is not pressurized until it returns to the heart
125
Q
Blood structure
A
- Blood is a tissue consisting of cells suspended in a liquid called plasma
- Plasma: (55%)
- Water
- Ions
- Proteins
- Nutrients, metabolites and wastes
- Cellular elements (45%)
- Erythrocytes (red blood cells)
- Leukocytes (white blood cells)
- Platelets
126
Q
How are respiratory surfaces specialized for gas exchange
A
- Gills, tracheae, and lungs
- Very large surface areas
(Greater than rest of body exterior) - Very thin exchange surfaces
- A single epithelial layer
127
Q
O2 concentration is respiratory media
A
- Respiratory media (source of O2)
- Air has a high concentration of O2
- Water has a much lower concentration of O2
- Animals that obtain O2 from water need to be much more efficient that animals that obtain O, from air.
128
Q
Why are gills unsuitable in terrestrial environments?
A
- Respiratory surfaces must be moist
- Respiratory surfaces of terrestrial animals are enclosed within the body to prevent excess water loss
(e.g., tracheae and lungs)
129
Q
Hemoglobin
A
- Attaches to red blood cells
- Has four oxygen binding cites
130
Q
Hormones in digestion
A
- Hormones regulate digestion and energy storage
- Secretion of digestive hormones is triggered by the presence of food
- Digestive hormones then trigger the secretion of gastric juices and digestive enzymes
131
Q
Colon function
A
- The colon functions in water reabsorption and formation and elimination of the feces
- Majority of water is reabsorbed in the small intestine, but colon also reabsorbs water
- Feces consist of undigested material and bacteria
132
Q
Parts of the large intestine
A
- Colon, cecum, and rectum
- The cecum functions in fermenting ingested plant material
133
Q
Insulin and Glucagon
A
- Hormones 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, secreted during energy deficit causes breakdown of liver glycogen, then muscle glycogen and fat
134
Q
Hormones in appetite regulation
A
- A satiety center in the brain generates the nerve impulses that make us feel hungry or full
- Leptin is produced by adipose and regulates long-term appetite
- Insulin and Peptide YY are secreted in response to a meal and ghrelin is secreted when the stomach is empty
135
Q
Obesity and evolution
A
- E.g. Grey seals have evolved a period of obesity critical to early survival
- Pups spend about 3 weeks nursing on very high fat milk
- Remain on land for several weeks
- Continue to live off blubber as they learn to swim and hunt
