Module 2 Exam Review Flashcards
Reductionism
when you look at the pieces to understand the whole
Emergence
the realization that the whole is more than the sum of the pieces
August Krogh principle
for every biological problem there’s an organism in which it can be most conveniently studied
similar geometry
2 animals have the same shape but differ in size
Hydrophobic signalling factors
- cannot cross cell membrane
- can be stored in vesicles and released on demand
- travel easily dissolved in extracellular fluid
Hydrophobic signalling factors (3 pts)
- can cross cell membrane
- can’t be stored so they diffuse upon synthesis
- travel attached to a water-soluble carrier
Water soluble factor
- must initiate a response by binding to a receptor on the cell membrane
- use secondary messengers inside the cell
fat soluble factor
receptor is inside the cell as it can freely cross the cell membrane
- triggers change in gene expression directly
Elements of endocrine signaling pathways(6)
- Synthesis- a hormone is synthesized in an endocrine gland
- Secretion- hormone somehow escapes the tissue(lipid soluble excreted upon synthesis, water soluble by exocytosis)
- transport- travels to target tissue
- reception- binds to a receptor at target tissue
- transduction- connects receptor to effector(uses ATP)
- response- ultimate consequence of the signalling cascade
Antagonistic hormones
a pair of hormones that have opposite effects; they act against each other
tropic hormones
hormones with the main job of regulating other hormones
Acclimation
response to a single environmental factor
Acclimatization
animals remodels itself in response to complex environmental change
endotherms
animals use internal metabolic processes as major heat source
ectotherms
can produce some heat but not enough to elevate temperature
Hypothalamus
gland that controls homeostasis in the body, releases tropic hormones to the pituitary gland
Posterior pituitary
a collection of termini of axons coming from the hypothalamus, axons of the hypothalamus send secretions to the posterior pituitary which then sends them to the rest of the body
Anterior pituitary
hormones travel through a vessel from the hypothalamus to the anterior pituitary where they trigger the release of hormones into circulation
Peptide hormones
- regulated by hypothalamus
- release direct or tropic hormones into blood
direct= act on target tissue (ADH) tropic= stimulate release of other hormones
“puppet”
Poikilotherm
an animals whose body temperature varies with its environment
Homeotherm
has a relatively constant body temperature
Metabolic rate
the sum of all energy used in biochemical reactions over a given time interval
Basal metabolic rate
metabolic rate of a resting, fasting, and non-stressed endotherm at a comfortable temperature
Standard metabolic rate
metabolic rate of a resting, fasting, and non-stressed ectotherm at a particular temperature
torpor
a state of decreased activity and metabolism that enables animals to save energy while avoiding difficult and dangerous conditions
Skeletal muscles/striated muscle
type of muscle responsible for voluntary movements
myofibrils
bundle of muscle cells containing thin filaments of actin and thick filaments of myosin
Cell body
part of the neuron that houses the nucleus and other organelles
dendrites
short, highly branched extensions of a neuron that receives signals from other neurons
axon
extension of a neuron that carries impulses away from the cell body, towards the target cell
synapse
where a neuron communicates with another cell across a narrow gap via a neurotransmitter
neurotransmitter
molecule that diffuses across synaptic terminal to trigger a response
Glial cells
cells of the nervous system that support and regulate neurons
Information processing
- sensory input
- integration
- motor output
Membrane potential
difference in charge across a cell’s plasma membrane due to distribution of ions
Resting membrane potential
membrane potential of a neuron not sending a signal(-70mV)
- expressed relative to the outside of the cell
Equilibrium potential
a cell’s membrane voltage at equilibrium
ion gated channels
open/close in response to concentration change
depolarized
inside of cell becomes less negative relative to outside the cell (sodium opening)
Hyperpolarized
inside of cell becomes more negative relative to outside (potassium opening)
Generation of action potentials
- resting state- gated Na and K channels are closed
- slow depolarization- stimulus opens Na channels, Na inflow depolarizes membrane
- depolarization- once threshold is reached, all voltaged gated Na channels are open, inside is positive
- repolarization- sodium channels close, K gated channels open to permit K outflow, inside of cell is -ve again
- hyperpolarization- K channels close, some Na open, membrane returns to resting potential
refractory period
short time after an action potential where a neuron cannot respond to another stimulus
EPSPs
excitatory post-synaptic potentials
- slight membrane depolarization at excitatory synapses
IPSPs
inhibitory post synaptic potentials
- slight membrane hyper-polarization
summation at axon hillock
combination of IPSP’s and EPSP’s that decide if a cell depolarizes to threshold voltage
plasticity
ability to change synaptic connections and functional properties of neurons
- done by reinforcing or making more connections
myoblasts
immature muscle cells
muscle tissue fibre arrangement
myosin(thick) and actin(thin) -> myofibrils -> muscle fibers ->tissue
myocyte
excitable and contractile cell type
Actin
- the microfilament that mysoin pulls itself along on (actin is train tracks, myosin is train)
- “thin filament”
myosin
- motor protein
- has a contractile head and flexible neck
- force generating
- “thick filament”
striated muscle
- thick and thin filaments are arranged in sarcomeres
- thick filament contraction shortens sarcomere
skeletal muscle
- responsible for rapid contraction
- attached to bones by tendons
- act antagonistically
- type of striated muscle
Cardiac muscle
- striated muscle that is mononucleated
- muscle cells called cardiomyocytes are connected at intercalated disks
Neuromuscular junction
synapse between a motor neuron and the muscle fiber, responsible for converting electrical impulses from nerve cell to muscle cell
Comparative physiology
Form vs Function
ex. allometric scaling (proportions differ)
Homeostasis
Maintenance of stable conditions
Allostasis
process that enables homeostasis
Hormones
Chemical signals that travel through lymph & blood
Autocrine
self signaling
“talk to self”
Paracrine
Beside
“talk to neighbours”
Endocrine
within
- travel long distances within body
Amino acid-derivatives
Dopamine, melatonin, thyroid hormones, adrenaline, melanin
- have plasma membrane (transmembrane) receptors
- soluble in blood
Peptide hormones
Prolactin, insulin, ADH, GH
- protein based
- have plasma membrane (transmembrane) receptors
- encoded by genes
Steroid
Cholesterol derivatives, sex hormones (testosterone), cortisol
- liquid based/liquid soluble
- have cytoplasmic receptors
- carrier proteins in blood
Fatty acid-derivatives
-
PGs, JH (juvenile hormone)
- mostly in insects
- liquid soluble
- made by enzymes
Signal synthesis
peptide hormones are synthesized by exposed genes
Other hormones synthesized by enzymes (ex. steroid synthesis)
peptide hormones synthesized as inactive precursors (ready to go)
- prohormones require cleavage for activation & Ca++ in cytoplasm to trigger release
Signal transduction
Synthesis > enzymatic or translation (peptide hormone)
transport > in blood
- soluble
- insoluble: carrier proteins
reception > receptor expressed on target cell
- steroids: cytoplasmic receptor
- other: transmembrane protein
transduce > connect receptor to effector
response >
Types of receptors
- GPCR
- Ligand-gated ion channels
- Receptor-enzyme
- Intracellular
- generally use 2nd messengers
Job= amplify response
Kinase
Enzyme that phosphorylates
Insulin
decreases blood sugar levels by stimulating uptake at the tissues
Glucagon
Increases blood sugar levels by stimulating glucose release by the liver into blood stream
Insulin-Glucagon pathway
Goal= maintain constant blood glucose level
Fast= blood sugar depleted
- Glucagon released
- Glucose released from glycogen storage in liver
Feast= blood sugar spikes
- insulin released
- cause blood glucose to be taken up by tissues
Regulation of sodium levels
Coordination between nervous system (hypothalamus) & endocrine (posterior pituitary)
Increased Na+
- posterior pituitary secrete more antidiuretic hormone (less water in urine)
- heart make more atrial natriuretic peptide (more Na+ in urine)
- inhibits aldosterone production in adrenal glands (more Na+ in urine)
Simplified:
Increase Na+ > hypothalamus > posterior pituitary -ADH- Water retention
Adrenal gland
HPA axis
(hypothalamus-pituitary-adrenal axis)
On the kidney!
hypothalamus
- CRH= corticotropic hormone
Anterior pituitary
- ACTH= adrenocorticotropic hormone
Adrenal gland
- release adrenaline
- relates to stress response
How does adrenal gland release different hormones from the different layers?
Different receptors on different layers (within adrenal gland: cortex, medulla) which trigger different cell responses
Phytoestrogens
plants possess estrogen-like compounds
Some vertebrates can be feminized by excess exposure to phytoestrogens (ex. minnows)
4 functions of nervous system
- Receive external & internal signals
- Transmit external & internal signals
- Integrate/interpret all the received signals
- Coordinate/command action/response(s) to those signals
CNS
brain & nerve cord
- forms from neural tube in development= ectodermal
PNS
all neurons & projections outside CNS
- homeostasis
Sensory function
sensory receptors send sensory info to CNS through sensory neurons
Automatic nervous system
Maintains homeostasis
- subconscious action
- response from internal environment
Sensory-somatic nervous system
- conscious
- response to external environment
Olfactory neurons
sensory receptor and neuron are the same
Myelin sheath
allows saltatory conduction
Nodes of Ranvier
axon potential occurs
Microglia
defense and scavenging in NS
Astrocytes
feed neurons, support them, & clean up their extracellular environment
Oligodendrocytes
Insulation of neurons to improve electrical transmission
Cnidarians
Nerve “net”
Annelids
more neurons
- ventral nerve chord with ganglia in each segment
Planaria
nerve chord with transverse nerves
- ganglion in head for integration
Echinoderms
ring around mouth & extensions out radially into legs
Other type of NS > evolution
- more nerves
- concentration of nerves (ganglia)
- Specialization of function of cells
- more complex synaptic contacts
- trends towards cephalization (brain)
Trend to specialization & integration
Simple molluscs
anterior ganglia & paired nerve chords
Advanced molluscs
brains with subdivisions
Flies
central brain with subdivisions with specialized function
- cephalisation
Coordination of responses
Neurons in more complex systems order themselves into sensory neurons, interneurons, * efferent neurons
Sensory > interneuron (no integration) > effector (motor response)
Action potential
- in axons
- “up down up”
start -70ish mV (resting potential)
-50ish mV threshold
+50ish max
- resting potential
- due to action Na+/K+ pump
- 3 Na out, 2 K in (3:2)
- negative charge inside - Voltage gated sodium channels open
- Na+ rushes in
- cell depolarized - Na channels close/K channels open
- Na+ channels fast to open/close
- Ka+ channels slow to open/close
- K+ rushes out - Repolarization
- K+ channels stay open - Hyperpolarization
- K+ channels too slow to close
- Too negative
- occurs at graph min
Parasympathetic
Rest & digest
- slows heart rate
- promotes vasoconstriction to muscles
- vasodilation to gut
- ACH (acetylcholine) is common neurotransmitter
Sympathetic NS
Fight or flight
- increase heart rate
- vasodilation to muscle
- adrenaline is common neurotrasnmitter
Acetylcholine
- released at neurotransmitter junctions
- excitatory in brain & skeletal muscles
- inhibitory in cardiac muscles
Action potential meets synapses
- Axon potential rushes down axon, slowly depolarizing (making inside cell more +)
- AP opens voltage gated Ca++ channels
- Ca++ influx triggers vesicle docking & neurotransmitter release into synapse
- Neurotransmitter bind to receptors at post-synaptic neuron: initiate downstream response
How to stop neurotransmitter release?
- degradation in synapse
or - reuptake
Autotroph
Self-nourishing
Heterotroph
Other-nourishing
Phototroph
photosynthesis
Chemotroph
energy from organic/inorganic molecules
Digestive system tasks
- mechanical processing & motility
- secretion
- digestion
- absorption
- elimination
Phagocytosis
Process used by protists to engulf solid particles by the cell membrane to form an internal food vacuole called phagosome
- form of endocytosis
- dominant in unicellular eukaryotes
- nutrients taken into cell
- vesicle containing digestive/hydrolytic enzymes
(ex. lysosome) - waste excreted & nutrients absorbed
Problem with intracellular digestion
increase chance of infection
selected pressure against due to this
Extracellular digestion
digestive enzymes secreted to digest extracellular nutrients & only digested nutrients enter cell
- infection decreases
Unidirectional gut
allows stepwise digestion
- requires specialization
Specialization of stomach cells
Goblet cells protect stomach lining from acid
parietal cell secretes acid (innate immune system)
Pepsinogen (inactive precursor) is an enzyme that digests proteins
Carbohydrate digestion (start & finish)
Start= mouth finish= small intestine
Protein digestion (start/finish)
start= stomach finish= small intestine
Nucleic acid digestion (start & finish)
Start/end= small intestine
Fat digestion start/end
small intestine
Absorption in small intestine
takes time > increase surface area of small intestine
- villi: adoptive structure, provide lots of SA & blood + lymph for absorption
- microvillus: increase SA available for absorption
Fat absorption
Cannot b e directly absorbed into blood, instead absorbed into lymph first
Ruminants
Contain endosymbiotic bacteria that live in rumen > digestive cellulose
- cellulose cannot be digested by animal enzymes
- microbial enzymes needed
4-chambered stomach
Rumen- exposed to bacteria that break down cellulose
Reticulum- regurgitate & reprocess
Omasum- further mechanical processing
Abomasum- digestive enzymes break down bacteria & release nutrients
Enterosymbionts
microbiome provides digestive enzyme diversity
fiber digestion
Lactose metabolism
some humans have lactase persistence
- continue to make lactase into adulthood
Large intestine
site of water reabsorption
a lot of bacteria live here!
Appetite control centre
Adipose tissue
- full of Ca+, secrete leptin & prevent hunger
Pancreas
- insulin present, message of satiety
Colon
- when full, secrete peptide yy, message of satiety
Stomach
- when empty, secretes ghrelin, stimulating appetite
Open-circulatory system
fluid is continuously exposed to entire body
Problem= as body size increases, harder to distribute nutrients
solve:
- pump fluids = open
- use vessels small enough to allow exchange = closed
Closed circulatory system
Fluid is contained in vessels
