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Biology > Animal biology > Flashcards

Animal biology Flashcards

1
Q

Fertilization

A

Forms the diploid zygote

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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
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3
Q

Differential gene expression

A

The foundation of the diverse cell type and behaviors seen throughout development

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4
Q

Morphogenesis

A

Occurs via changes in cell position, shape, survival, and forms organs

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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)
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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
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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
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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
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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
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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

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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
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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
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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)
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14
Q

Gastrulation

A
  • Results in a three-layered gastrula
  • Ectoderm, mesoderm, endoderm
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15
Q

Gastrulation steps

A
  1. Cells in the vegetal hemisphere push inward (form the blastopore and blastocoel)
  2. Outer cells (future endoderm and mesoderm) roll inward
  3. Blastocoel collapses and a new cavity - archenteron is formed
  4. Cells at the animal pole (future ectoderm) spread over the outer surface
    ectodermal and endodermal cells express different genes
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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
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17
Q

Formation of the neural tube

A
  • Ectodermal cells change shape during neural tube formation
  • Ectoderm, neural plate, microtubules, actin filaments
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18
Q

Programmed cell death

A
  • Also shapes embryos
  • Cells undergo apoptosis (programmed cell death)
  • Ex. removal of webbing between digits
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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!

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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
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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

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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
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23
Q

Central nervous system (CNS)

A
  1. Brain
  2. Spinal cord
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24
Q

Peripheral nervous system (PNS)

A
  • Cranial nerves
  • Ganglia outside CNS
  • Spinal nerves
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25
Q

Information processing

A
  1. Sensory input (sensor)
    through peripheral (sensory neuron)
  2. Integration (CNS)
    through peripheral (motor neuron)
  3. Motor output (effector)
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26
Q

Endocrine cells

A

Secrete hormones into the bloodstream, affecting target cells to regulate physiology and behavior

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27
Q

Hypothalamus

A

A brain region that acts as the “master regulator” of the endocrine system, primarily through the pituitary gland

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28
Q

Posterior pituitary

A
  • Made up of axons of neurosecretory cells of the hypothalamus
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29
Q

Bioenergetics

A

The overall flow and transformation of energy within an organism

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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
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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)
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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
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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
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34
Q

The four stages of food processing

A
  1. Ingestion
  2. Digestion
  3. Absorption
  4. Elimination
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35
Q

Ingestion

A
  • Structures associated with ingestion are the most diverse part of the digestive system
  • Mammalian teeth reflect diet
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36
Q

Four main feeding mechanisms

A
  1. Suspension feeders and filter feeders (e.g. whale)
  2. Substrate feeders (e.g. caterpillar)
  3. Fluid feeders (e.g. mosquito)
  4. Bulk feeders (e.g. snake)
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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
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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)
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39
Q

Stomach

A
  • Epithelium secretes gastric juice
  • Food mechanically mixed with gastric juice to become chyme
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40
Q

Gastric glands 3 specialized types of cells

A
  1. Mucous cells
  2. Chief cells (make pepsinogen)
  3. Parietal cells (secrete hcl (gastric acid))
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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
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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
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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
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44
Q

Liver

A
  • Produces bile
  • Regulates distribution of nutrients to rest of body
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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
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46
Q

Temperature Regulation vs Conformity

A

Animals either regulate their physiological parameters OR allow their bodies to conform to external conditions

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47
Q

Regulators

A

Regulators use homeostatic mechanisms to control internal changes

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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

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49
Q

Physiological parameters being regulated

A
  • Thermoregulation (temperature)
  • Osmoregulation (body water, and solute concentration)
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50
Q

Thermoregulation

A

The maintenance of an internal temperature within a tolerable range

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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

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52
Q

Thermal strategies

A
  • Can be defined based on the source of heat
  • Endotherms vs Ectotherms
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53
Q

Ectotherms

A

Rely primarily on external environment as their major heat source

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54
Q

Homeotherms vs poikilotherm

A
  • Body temp of poikilotherms varies with the environment
  • Homeotherms have relatively constant body temperature
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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
  1. Evaporative heat loss
  2. Circulatory adaptations
  3. Metabolic heat production
  4. 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
  1. Hyperosmotic
    - Higher solute concentration
    - Lower free H2O concentration
  2. Hypoosmotic solution:
    - Lower solute concentration
    - higher free H2O concentration
68
Q

Osmolarity

A
  1. Hyperosmotic fluid:
    - Higher (solutes) outside cell
    - Water leaves cells through osmosis
    - Cells that lose too much water shrivel and (may) die
  2. Hypoosmotic fluid:
    - Lower (solutes) outside cell; (higher (S) inside)
    - Water enters cells through osmosis
    - Cells that gain too much water burst and die
  3. 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
  1. Barrier defenses:
    - Skin
    - Mucous membranes
    - Secretions
  2. 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
  1. 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
  1. A circulatory fluid
    - Blood in a closed circulatory system
    - Hemolymph in an open circulatory system
  2. Set of interconnecting vessels
  3. A muscular pump
100
Q

Two types of circulatory system

A
  1. Open circulatory system
    - Hemolymph in sinuses surrounding organs
  2. 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
  1. Deoxygenated blood returning from the systemic circuit enters via the superior vena cava
  2. Right atrium
  3. When the right atrium contracts, blood is rushed into the right ventricle
  4. When the right ventricle contracts, blood is pushed into the pulmonary artery sending it to the lungs
  5. Oxygenated blood returning from the pulmonary circuit enters via the pulmonary veins
  6. It flows into the left atrium
  7. 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

Biology (5 decks)

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