Test 3 Flashcards
Animal Cell Characteristics
- heterotrophs
- multicellular
- no cell wall
When was the first evidence of animals? What was it?
- 700 mya
- first animal fossils were sponges
What are sponges related to?
- choanoflagellates; are sessile (immobile) and filter feeders
Major Animal Phyla
- Porifera
- Cnidaria
- Platyhelminthes
- Nematodes
- Mollusca
- Annelida
- Arthopoda
- Echinodermata
- Chordata
2 General Trends in Animal Evolution
- increase in mobility
- increase in size
What is required for Increase in Mobility
- requires:
a) tissue: muscles, nervous tissue
b) skeleton
c) orientation (having a front and a back end)
What is the front end of an animal used for?
- sensory system
- feeding structures
What is the rear end of an animal used for?
- locomotive structures
What is required for Increase in Size
requires:
a) circulatory system
b) organs
What is the circulatory system used for?
movement within the body
What are organs used for?
they work together within the circulatory system
Sessile definition
immobile
5 Characteristics of the Animal Phyla
- symmetry
- level of organization
- gut development
- type of coelom
- segmentation
What does symmetry help with? What are the three versions?
- helps with mobility and orientation
- 3 versions:
a) asymmetry
b) radial symmetry
c) bilateral symmetry
Asymmetry
- porifera
- sponges are not mobile so they do not need symmetry
Radial Symmetry
- more than 2 ways to divide the body and get mirrored halves
- cnidaria; good for up and downward movement
Bilateral symmetry
- only one way to divide body in half and get mirrored halves
- all other phyla
What are the 3 levels of organization?
- cellular level
- tissue level
- organ level
Cellular Level
- body is composed of specialized, mostly totipotent cells that are capable of living on their own
- lack tissue, so cells work independently
- of cut in half, new organism forms
- porifera
Tissue Level
- body composed of tissue and lacks organs
- cells work together
- cnidaria
Organ Level
- body composed of organs
- all other phyla
Tissue
group of similar cells that work together to perform a specific function within an organism
Organ
group of tissue in an organism that has adapted to perform a specific function
Blastula
- 64 cell stage
- totipotent
- if split, you get twins
- 2 things can happen:
a) can become ciliated
b) gastrulation
Blastocoel
fluid filled cavity in blastula
What happens if the blastula becomes ciliated?
- develops into a sponge (porifera phylum)
What happens if the blastula goes through gastrulation?
- develops into a gastrula
Gastrula
- differentiated
- 2 embryonic tissues:
a) ectoderm
b) endoderm
Ectoderm
- all cells on the outside of gastrula
- partially specialized tissue that becomes integument and/or the nervous system
Endoderm
- in the “dimple”/archenteron of the gastrula
- partially specialized tissue that becomes the lining of the digestive system
Archenteron
- embryonic gut
What are the two things that can happen to the gastrula?
- archenteron expands and fills interior
- third embryonic tissue forms
What happens when the archenteron expands and fills the gastrula interior?
- you get a gastrovascular cavity
Gastrovascular cavity
- body formed from 2 embryonic tissues
- diploblastic
- responsible for the digestion of food and transport of nutrients
- cnidaria
- tissue level of organization
What happens if a third embryonic tissue forms from the gastrula?
- you get a triploblastic cell
- creates the mesoderm
- organ level of organization
Mesoderm
- partially differentiated tissue that becomes muscle, skeletal system, circulatory system, and organs
Blastopore
- opening that forms during gastrulation
- later develops into mouth or anus
Gastrulation
- embryonic stage where the 3 germ layers (ectoderm, endoderm, and mesoderm) are established
Diploblastic
organism with 2 germ layers: ectoderm and endoderm
Triploblastic
organism with 3 germ layers: ectoderm, endoderm, mesoderm
Gut Development
- 2 aspects
a) completeness
b) orientation
Gut Development: Completeness
a) no gut: porifera
b) incomplete gut: one opening; cnidaria and platyhelminthes
c) complete gut: 2 openings; more efficient bc start and end; all other phyla
Gut Development: Orientation
- protostome
- deuterostome
Protostome
- blastopore becomes the mouth
- nematodes, mollusca, annelida, arthopode
Deuterostome
- blastopore becomes the anus
- echinodermata and chordata
Type of Coelom
- triploblasts
- 3 versions
a) acoelom
b) pseudocoelom
c) coelomate
Coelom
body cavity that houses organs
Acoelom
- coelom is filled with mesoderm that surrounds organs
- heavy and less flexible
-ex: tapeworms - platyhelminthes
Pseudocoelom
- not completely lined by mesoderm
- organs move freely
- nematodes
Coelomate
- completely lined by mesoderm
- mesoderm and endoderm being close to each other allows for complex digestive systems
- mollusca, annelids, arthopoda, echinodermata, chordata
- organs are held in place
Segmentation
- body cavity is divided into discrete segments
- chordata, annelida, arthopoda
What is segmentation good for?
Segments have unique set of genes that are much different from each other that allow for complex bodies
What are the 4 major animal tissue types?
- epithelial tissue
- connective tissue
- nervous tissue
- muscle tissue
Epithelial Tissue
- covers the body surfaces
- not vascularized
- 3 shapes
- functions:
a) protection from predators, desiccation, bacteria, abrasion
b) thermal regulation
c) absorption
d) secretion
e) diffusive exchange
What are the 3 epithelial tissue shapes?
- squamous epithelia
- cuboidal epithelia
- columnar epithelia
What does it mean to be vascularized?
to have a blood supply
What are the 2 versions of Squamous Epithelia?
simple or stratified
Simple Squamous Epithelia
- flat cells
- barrier between 2 compartments
- one cell layer thick
- rapid movement of gas exchange
- derived from ectoderm
- in lungs and capillary blood cells
Stratified Squamous Epithelia
- multiple layers of flat cells
- basal layer is living
- outer layers are dead and full of keratin
- protection from abrasion
- skin, esophagus
What does keratin do within epithelial cells?
- makes cells waterproof
Cuboidal Epithelia
- secretory
- lines the glands
- derived from mesoderm
- in kidneys
Columnar Epithelia
- lining of the digestive system
- absorption/selective uptake of nutrients
- some secretion of digestive enzymes
- lifespan of 3 days
- from endoderm
Connective Tissue
- used for support, connections, and storage
- composed of cells in an extracellular matrix
- 5 types
What does extracellular matrix mean?
- ground substance and fibers that occupies the empty spaces between cells
- gel like
What are the 5 types of of connective tissue?
- loose connective tissue
- dense connective tissue
- cartilage
- bones
- vascular
Loose connective tissue
- flexible
- well vascularized
- makes connections
- some storage
- 2 types
What are the 2 types of loose connective tissue?
areola and adipose
Areola tissue
- fibroblasts
- large cells with a matrix of ground substance and 2 protein fibers (collagen and elastin)
- holds skin intact
What does blasts mean, like in fibroblast?
blasts means to secrete
fibroblasts secrete fibers
Collagen
- high tensile strength
- prevents tissue from tearing
Elastin
- provides elasticity
Adipose tissue
- larger fibroblasts called adipocytes
- large vacuoles full of lipids
- few fibers
- fat tissue
Dense connective tissue
- few small fibroblasts
- little ground substance
- lots of collagen
- poorly vascularized
- 2 types
What are the 2 types of dense connective tissue?
- regular dense tissue
- irregular dense tissue
Regular Dense Tissue
- collagen fibers are parallel
- ligaments, tendons
- have to be strong
- similar to cables
What do ligaments do?
- connect bones across joints
What do tendons do?
- connects muscles to bones
Irregular dense tissue
- mesh of collagen fibers
- flexible but strong
- kidneys and dermis
Cartilage
- skeletal material used for flexible, structural support
- poorly vascularized
- composed of chondrocytes in a peptidoglycan matrix
Peptidoglycan matrix
- proteins and sugars
- collagen
- gel like
What are the cells of cartilage called?
- chondrocytes
Bones
- rigid skeletal material
- well vascularized
- composed of osteocytes in a calcium/phosphate matrix
- 2 types
How are bones arranged?
- in osteons
- tubular arrangements of osteocytes around a central canal
Calcium phosphate matric
- arranged in crystals
- not permeable
Central Canal
- contains blood vessels
Canaliculi
- channels that connect osteocytes to central canal
- allows for blow flow
Why can bones heal relatively quickly?
- because they have a good source of blood, energy, and nutrients
What are the 2 types of bones?
- cortical bone
- cancellous bone
Cortical bone
- where bone gets its strength
Cancellous bone
- stores marrow and provides horizontal support
What does bone marrow do?
produces blood cells
Bone growth: Length
- epiphyseal plate divides to produce osteocytes on shaft side
Epiphyseal plate
- layer of cartilage present during growth period that vanishes after puberty
- used for growth in length
Bone growth: girth
- osteoblasts and osteoclasts
Osteoblasts
- adds new bone to outside
Osteoclasts
- removes old bone from the inside
Stimulants and Inhibitors of Osteoblasts
Stimulants:
- stress/pressure on bones
- hormones (testosterone, estrogen)
- calcitonin
Inhibitors:
- parathyroid hormone
- age (40-45)
Calcitonin
- secreted in response to high Ca2+ levels in blood
Parathyroid hormone
- secreted in response to low Ca2+ levels in blood
Stimulants and Inhibitors of Osteoblasts
Inhibitors:
- stress/pressure on bones
- hormones (testosterone, estrogen)
- calcitonin
Stimulants:
- parathyroid hormone
- age (40-45)
What is bone strength a function of?
- function of thickness of cortical bone
- function of rates of osteoblasts and osteoclasts
Menopause vs bone growth
- menopause is a decline in estrogen
- women are more prone to weak bones at old age due to lack of estrogen
What can we control with bone growth and decline?
- our peak bone strength
- physical activity before and after peak
- our diet
Vascular Tissue
- blood
Nervous Tissue
- detects stimuli
- composed of neurons
What are the 3 types of neurons?
- sensory neurons
- interneurons
- motor neurons
Sensory neurons
- detects stimuli and signals central nervous system
Interneurons
- processes stimuli and triggers a response
Motor neuron
- sends signal to effector
What are the 3 transmembrane proteins in nervous tissue?
- potassium leak channel
- Na/K atpase
- Voltage gated sodium channel (VGNC)
K leak channel
- “always” open
- regulates resting potential
- allows potassium to flow across the membrane
Na/K atpase
- always working
- pumps 3 Na+ out of cell and 2 K+ into cell
Voltage Gated Sodium Channel (VGNC)
- when open, allows Na+ to cross membrane (in or out)
- when closed, membrane is at rest
Polarized membrane
a positive and negative charge on opposite sides of membrane
What are the two forces acting on potassium?
- diffusion (outward)
- electrical force (inward)
Resting Potential
- neuron at rest has a voltage gradient of -70 mv
What are the three VGNC configurations?
- closed
- open
- inactive
VGNC configuration: Closed
- when voltage gradient is < -40 mv
VGNC configuration: open
- brief configuration that occurs if voltage gradient is > -40 mv
- Na+ moves into cell
VGNC configuration: inactive
- brief configuration that occurs after the VGNC has been opened
- Na+ cannot cross and channel cannot be reopened
- refractory period
What is the VGNC mv threshold?
-40 mv
Action potential
- pulse of depolarization moving down a polarized membrane
Intensity of signal
- function of amount of action potentials send down a neuron
What are the 7 types of protein receptors?
- chemoreceptors
- mechanoreceptors
- photoreceptors
- proprioreceptors
- thermoreceptors
- electroreceptors
- magnoreceptors
Chemoreceptors
- detect chemicals
- responsible for taste and smell
Mechanoreceptors
- respond to pressure change
- responsible for touch and hearing
Photoreceptors
- responsible for vision
- detect certain lights
Proprioreceptors
- detect orientation of body
Thermoreceptors
- respond to change in temperature
Electroreceptors
- detect electrical current
Magnoreceptors
- detect magnetic fields
Two events that can start an action potential
- sensory event
- synapse
Sensory Event
- sensory neurons contain protein receptors on their dendrites that respond to specific stimuli by changing shape and allowing Na+ to cross the membrane
Synapse
- AP is passed from pre-synaptic neuron to post-synaptic neuron
Axon termination of presynaptic neuron/communication between neurons/synaptic event
- AP reaches the axon termination of presynaptic neuron
- causes VGCCs to open and Ca2+ flows into cell
- causes exocytosis of neurotransmitter
- neurotransmitters bind to receptor proteins on post-synaptic neuron
- neurotransmitter receptor proteins change shape and creates a channel for Na+ to flow into cell and depolarizes the membrane (starts an AP)
- Acetylcholinesterase removes acetylcholine from receptors and allows the post-synaptic neuron to re-polarize
What are the three types of muscle tissue?
Skeletal
Smooth
Cardiac
What is muscle tissue?
Contractile tissue
Skeletal Muscle
- composed of large, multinucleate, striated cells that are voluntary
- the more nuclei, the more proteins you can make in a short period of time
Smooth Muscles
- smaller, thinner, non-striated, uninucleate cells that are involuntary
Cardiac Muscle
- short, uninucleate, branched, striated cells
- connected through intercalated discs
Intercalated discs
- connects cardiac muscle
- composed of anchor and gap junction
What are the functions of anchor junctions in cardiac muscles?
- allows muscles to contract without tearing apart
What are the two types of skeletal muscle?
- slow twitch
- fast twitch
Slow Twitch
- well vasculated
- many mitochondria
- myoglobin
- stamina
- less contractile protein
- smaller
Fast Twitch
- less vascularized
- few mitochondria
- no myoglobin
- strength
- more contractile protein
- larger
What are the three important components of a skeletal muscle fiber?
- sarcolemma
- sarcoplasmic reticulum
- myofibrils
Sarcolemma
- membrane
- polarized at rest
- can produce action potentials
- contains k leak channels, na/k atpase, and VGNCs
Sarcoplasmic reticulum
- folded membrane bound bag that stores Ca2+
- membrane is polarized at rest
- contains Ca2+ atpase and VGCCs
- pumps Ca2+ into SR
- can conduct action potentials
- connected to the sarcolemma through transverse tubules
Myofibrils
- bundles of contractile proteins that run the length of the cell
- arranged into sarcomeres
Sarcomere
contractile unit of myofibrils
Z line
Protein structure that connects two adjacent sarcomeres
What makes up the actin myofilament?
- actin
- tropomyosin
- troponin
What makes up a myofibril?
myosin myofilaments and actin myofilaments
At rest, why can’t actin and the myosin head bind?
- tropomyosin is in the way because troponin is holding it in place
- muscle cannot contract
Simple Reflex Arc
- sensory event partially depolarizes area around a VGNC, creating an action potential
- the action potential moves down the polarized membrane, partially depolarizing other VGNCs along the way, while previous VGNCs become inactive and/or closed
this synaptic event occurs for sensory neuron to interneuron and interneuron to motor neuron (3-7): - action potential reaches the axon termination of interneuron neuron and causes VGCCs to open
- Ca2+ flows into cell and causes exocytosis of neurotransmitters (acetylcholine)
- neurotransmitters (acetylcholine) bind to neurotransmitter receptor proteins on post-synaptic neuron
- receptor proteins change shape and creates a channel for Na+ to flow into cell, which depolarizes the membrane and starts an AP
- acetylcholinesterase removes acetylcholine from receptors and allows the post-synaptic neuron to re-polarize
- AP reaches axon termination of motor neuron and is sent to the muscle by a synaptic event through a neuromuscular junction. it spreads over the sarcolemma through transverse tubules over the sarcoplasmic reticulum membrane, VGCCs open, and calcium flows out to cytoplasm
- calcium binds to troponin
- troponin changes shape and pulls tropomyosin from the MH binding site
- myosin head binds to actin (forms cross bridge)
- power-stroke occurs (MH changes from obtuse to acute, pulls z lines closer together, causes sarcomere to short, and muscle contracts)
- ATP binds to MH and breaks cross bridge
- ATP is hydrolyzed
- energy from the hydrolization of ATP is used to return MH heads to “rest” position (obtuse angle)
- if calcium is still present in cytoplasm, another contraction cycle occurs.
Porifera
- Asymmetrical
- Cellular
- No gut
- Acoelomate
- No segmentation
Cnidaria
- Radial symmetry
- Tissue
- Incomplete gut
- Acoelomate
- No segmentation
Platyhelminthes (tapeworms/flatworms)
- Bilateral symmetry
- Organ
- Incomplete gut
- Acoelomate
- Not segmented
Nematoda (roundworms)
- Bilateral symmetry
- Organ
- Complete gut
- Psueocoelom
- No segmentation
Annelida (earthworms, segmented worms)
- Bilateral symmetry
- Organ
- Complete gut
- Coelomate
- Segmented
Mollusca (snails, octopus)
- Bilateral symmetry
- Organ
- Complete gut
- Coelomate
- No segmentation
Arthropoda (insects, crustaceans)
- Bilateral symmetry
- Organ
- Complete gut
- Coelomate
- Segmented
Echinodermata (starfish)
- Bilateral symmetry
- Organ
- Complete gut
- Coelomate
- No segmentation
Chordata
- Bilateral symmetry
- Organ
- Complete gut
- Coelomate
- Segmented
What is the contraction cycle?
- once the action potential reaches the muscle (the effector) it spreads over the sarcolemma through transverse tubules over the sarcoplasmic reticulum membrane, VGCCs open, and calcium flows out to cytoplasm
- calcium binds to troponin
- troponin changes shape and pulls tropomyosin from the MH binding site
- myosin head binds to actin (forms cross bridge)
- power-stroke occurs (MH changes from obtuse to acute, pulls z lines closer together, causes sarcomere to short, and muscle contracts)
- ATP binds to MH and breaks cross bridge
- ATP is hydrolyzed
- energy from the hydrolization of ATP is used to return MH heads to “rest” position (obtuse angle)
Neuro muscular junction
synaptic connection between the axon termination of a motor nerve and a muscle
Affect of an AP moving across a muscle?
- rapid influx of calcium into cytoplasm
Do actin and myosin have a low or high affinity?
high
Myosin, troponin, actin, and tropomyosin are all ___?
proteins
What keeps calcium present in cytoplasm/VGCCs on SR open?
- constant APs sent down a neuron
- takes continuous APs to contract a muscle
Why is MH at a “rest” position?
- it takes energy to go from acute to obtuse, so obtuse position has more energy
What is a contraction?
movement of MH going from a high energy state to a low energy state, then using ATP to move from low energy state to high energy state
What is the purpose of troponin binding to Ca2+?
- to move tropomyosin off the MH binding site
What happens if you run out of ATP?
if due to extreme exercise:
- cross bridge can’t break, so muscle cant relax = CRAMPING
if due to death:
- calcium gradually leaks out of SR membrane and triggers one incomplete contraction cycle
- body stiffens
= rigor mortis
Myoglobin
Protein that stores oxygen in slow twitch muscles
