BIOL 3350 EXAM 2

9. Lecture 9: metabolic scaling

·       What is the “thermoneutral zone”?

o   Range of temperatures of the immediate environment where a being can maintain normal body temperature without needing to use excessive energy

·       What is a “basal metabolic rate”?

o   Minimum number of calories body needs to function at a basic level

·       Understand metabolic scaling and how metabolic rate relates to body size.

o   Measured by oxygen rate

o   Affected by temperature differences outside TNZ

o    

·       What is the difference between allometric scaling and isometric scaling?

o   Allometric: one trait increases more rapidly than another

§  Scales this way because as animals get bigger, they struggle to supply cells with energy and nutrients

§  Based on species

§  Proportional, body weight to weight specific metabolic rate

o   Isometric: everything increases proportionally

§  Size is relative to body size and weight

10. Lecture 10: digestion

·       Why do animals need nitrogen?

o   essential building blocks of amino acids, and these are required for most bodily functions.

·       How does bodily use and storage differ for amino acids, lipids, and carbohydrates?

o   Amino acids: essential for enzymes & transportation. Required to build proteins, and must be obtained through diet.

o   Lipids: essential for cell membranes, stores energy (high energy/unit of weight), made of fatty acid chains

§  Stored long-term as triglycerides

o   Carbohydrates: ATP production through glycolysis

§  Structural role in invertebrate and plants; exoskeleton = chitin, plants = cellulose

·       How does the body absorb lipids?

o   Lipids are broken down by lipidase -> fatty acids (hydrophobic) emulsified by bile salts into small droplets -> carried to cell membranes by micelle.

·       Know the major categories of molecules that we need to obtain from our diet to survive and why we need them:

o   Essential amino acids: can’t be synthesized fast enough for demand, must be obtained through diet (nitrate in soil -> plants -> ingested)

o   Essential fatty acids: required for energy storage, cell functions, and the absorption of vitamins.

o   Vitamins: compounds that cannot be synthesized, consumed by plants, vitamins released, adaptation to needing/requiring them. Lipid soluble in vertebrates, water soluble for general functions.

·       Know the general function of the small intestine, large intestine, and pancreas in humans.

o   Small intestine: aka midgut, main digestion/absorption (proteins, carbs, lipids)

o   Large intestine: aka hindgut, absorbs water and stores waste

o   Pancreas: secretes many enzymes into the small intestine. These enzymes break down proteins

·       Why do endopeptidases need to be activated when they are released into the digestive tract?

o   Endopeptidases are responsible for breaking down proteins, so they need to be activated to avoid self-digestion

·       What is the difference between digestion and fermentation?

o   Digestion: breakdown by endogenously produced enzymes

o   Fermentation: breakdown by enzymes by microbial symbionts

§  allows for breakdown requiring enzymes found in grass/vegetation

·       Why is it beneficial to have symbiotic microbes in our digestive tract?

o   Responsible for breaking down ingested food with bacteria in the gut.

·       How do ruminants deal with consuming so much plant material? How does this compare to hindgut fermenters?

o   Ruminants: Breakdown heavy diet of plants by regurgitation to improve digestibility.

o   Hindgut: use microbes in the cecum/colon for further digestion

·       What are some factors that may cause the gut microbiome across species and among individuals?

o   Varies by species due to genetics, diet, and environmental factors.

11. Lecture 11: neural physiology

·       Know the 4 major parts of a neuron and what each of them does

o   Dendrite: receive input from other neurons

o   Soma: integrate input signal, filled with cargo packaged to be carried and released at other end of the neuron.

o   Axons: carry signals from cell body to synaptic terminals

o   Presynaptic: neurotransmitters released

·       Know the function of the 4 major types of glial cells

o   Oligodendrocytes: responsible for myelin sheath production in the CNS.

o   Schwann cells: responsible for myelin sheath production in the PNS, made of layers of wrapped glial cells around axons, increase speed of action potential

o   Astrocytes: star-shaped projections connecting neurons to blood vessels, carry metabolic substrates and uptake neurotransmitters/ions from extracellular space at synapses.

o   Microglial cells: mediate immune responses, consume pathogens/cellular debris from injury through phagocytosis.

·       What is membrane depolarization? Hyperpolarization?

o   Depolarization: inside of the cells are negative + excitatory

o   Hyperpolarization: inside of the cell is positive

·       Know the basics of how an action potential is generated (Quiz 3 schematic). What  are K+ and Na+ channels are doing when a neuron is at rest, in the rising phase, and the falling phase?

*CHECK QUIZ 3

       @depolarization: voltage gated ion channels

       @ repolarization: Na+ channels close, K+ channels opens

12. Lecture 12: synaptic transmission

·       Understand the concept of neuroplasticity - both structural (changes in dendritic spines) and based on neurotransmitters.

o   Neuroplasticity – ability of the brain to change its structure and function in

§  Structural: physical structure changes including growth of new neurons, and/or dendritic remodeling.

§  Neurotransmitters: physical adjustments, can go from electrical to chemical synapses and vice versa.

·       Pros and cons of electrical and chemical synapses

o   Electrical:

§  PRO: high-speed transmission, direct current flow from neuron-neuron

§  CONS: signal weakens when transmitted to next cell

o   Chemical:

§  PRO: amplification of post-synaptic neuron responses, and communication is modifiable “synaptic plasticity”

§  CONS: slower than direct electrical passage

·       How does depolarization trigger neuropeptide release from the synaptic terminals?

o   Depolarization opens calcium channels, the calcium binds to protein synaptotagmin, activating complex fusion of cell membranes.

o   Cells go through exocytosis/recycling, releasing neuropeptides from synaptic terminals.

·       How do neuropeptides interact with dendrites? (2 major receptor types)

o   1) Voltage-gated Channels: open action potential Ca2+ influx triggers neurotransmitter release

o   2) Metabotropic, G protein-coupled: direct interaction with neurotransmitters, activation of metabolic cascade in postsynaptic neuron

·       What are the major differences between small-molecule neurotransmitters and neuropeptides?

o   Small molecules: amino acids and/or their derivatives, synthesized in axon terminals, packaged into synaptic vesicles by transport molecules

o   Neuropeptides: short chains of amino acids, produced & released by neurons that act as chemical messengers.

§  synthesized as a larger molecule polypeptide, carried to vesicles, requires high action potential, and broken down by peptidases

·       Know the basics of exocytosis and endocytosis of synaptic vesicles

o   Exocytosis: dependent on calcium ion concentrations, the release of large molecules from cytoplasm to cell exterior.

o   Endocytosis: internalization of proteins, polysaccharides, and other cells. Crucial for cell signaling, metabolism, and development.

·       What is long-term potentiation?

o   After stimulation, long-lasting enhancement of synaptic transmission. Axon projections are stimulated, resulting in amplified and prolonged response to electrical stimulation.

13. Lecture 13: sensory processes

·       Understand sensory input goes to specific regions of the brain. Size of a designated region may vary based on the amount and type of sensory information the organism relies on.

·       What are the basics of membrane depolarization from mechanical stimulation? How do the ion channels differ from others we have discussed?

o   Mechanoreception: response to mechanic stimulus (touch, pressure, hear)

o   Chemoreception: response to chemical stimulus

o   Photoreception: response to light

·       How does taste cell signaling differ for salty/sour tastes vs sweet/bitter/umami tastes?

o   Salty/sour: cells with ionotropic receptors

o   Sweet/bitter/umami: cells with metabotropic receptors

·       Where are olfactory receptor cells found? Where are their sensory cilia located? Which brain structure do olfactory neurons send information to?

o   Located in the cell bodies of the olfactory epithelium (nasal cavity)

o   Dendrites extend to mucous layer and ends extend to the dendritic knob that is attached to the sensory cilia.

o   Axons connect to olfactory bulb in forebrain

·       How does light interact with photopigment receptors?

o   GCPRs are specialized receptor cells with chromophore to absorb light inducing conformational change within opsin (retinals).

·       What are the two major photoreceptor cells in vertebrates and how do they differ? Where in the eye are they located?

o   RODS: response to dim light, use rhodopsin as opsin in receptor

§  Discs are not continuous, without an outer membrane, with cyclic GMP (cGMP) usage

§  Light induces conformational change in rhodopsin, triggering GCPR cascade, reduces cGMP #’s, closing ion channels

o   CONES: response to bright light, using 2+ opsin types

§  Connected by modified cilium, and has a membrane with photopigments in flattened disks

14. Lecture 14: nervous system function

·       Know the difference between the central nervous system and peripheral nervous system.

o   CNS: integrative controller

o   PNS: connection to the rest of the body to the CNS

§  Autonomic

·       Sympathetic

·       Parasympathetic

§  Somatic

·       Sensory

·       Motor

·       What are the two major functions of the somatic nervous system?

o   Sensory: communication through spinal nerves to areas below the neck.

§  Project from dorsal root ganglion (DRG) of the spinal cord to the skin

§  Sensory nerve endings with specialized endings for mechanosensory input

§  ALSO includes cranial nerves – 12 pairs for communication above the neck

o   Motor: somatic neurons directly innervate muscle cells and communicate via acetylcholine as a neurotransmitter.

·       What is a nerve made of?

o   When axons of multiple neurons in PNS bundle together

o   Dendrite -> soma -> axon -> node of Ranvier

o   Nervous system is organized neuron network for conduction of electrical and chemical signals for communication

§  Grey Matter: cell bodies, synapses

§  White Matter: tracts of myelinated axons

·       What are the three divisions of the autonomic nervous system and what are their general functions?  

o   1) Sympathetic: “fight or flight”, response to sensory system

§  Coordination of skeletal muscles/motor control

o   2) Parasympathetic: “rest & digest”, calming

o   3) Enteric: gut mobility, gut nerves communicate to brain via vagus nerve

§  Vagus nerve:  90% connections from gut to brain, composition influences brain/behavior

·       How does neuronal signaling differ between the somatic nervous system, the sympathetic division, and the parasympathetic division?

o   Somatic: signals projected from dorsal root ganglion (DRG) of spinal cord to the skin

§  Sensory nerve endings with specialized endings for mechanosensory input throughout the body

§  Cranial nerves are for the head and neck

§  Somatic – motor control, neurons directly innervate muscle cells and communicate via acetylcholine

o   Sympathetic: two neuron communication

§  Short preganglionic neuron

§  Longer postganglionic

o   Parasympathetic: two neuron communication

§  Long preganglionic neuron

§  Short postganglionic inside the target organ

·       Know key regions of the brain and their basic function: cerebrum, hypothalamus, cerebellum, medulla oblongata, olfactory bulb. 

o   Cerebrum: high sensory and motor functions, learning, memory, & emotions

o   Hypothalamus: homeostatic and endocrine regulation, circadian clock

o   Cerebellum: motor coordination

o   Medulla Oblongata: autonomic and respiratory control

o   Olfactory Bulb: receives neural input about smells from nasal cavity

15. Lecture 15 & 16: endocrine physiology

·       What are the major differences between neuronal and hormonal signaling?

·       What are the three major categories of hormones and how do they differ?

·       Know the role of the pituitary in hormonal signaling.

·       Know the basics of the HPA axis and the stress response.

·       What do insulin and glucagon do, and when are they secreted?

Participation Q’s:

1)      Arrange animals from lowest mass-specific metabolic rate to highest: elephant, raccoon, wolf, bear, mouse

a.      Elephant, bear, wolf, raccoon, mouse

2)      ____ aids in the digestion of lipids by emulsifying them

a.      Bile salt

3)      Energy reserves in the body are stored mainly as:

a.      Lipids

4)      What are cell types are immune cells?

a.      Microglia

5)      What is the function of myelin sheaths on the axon?

a.      Increase speed of action potential

6)      The peripheral nervous system is made up of the:

a.      None of the above: brain, spinal cord

7)      What facilitates the slowest form of communication at a synapse?

a.      Metabotropic receptors

8)      Small-molecule neurotransmitters are synthesized in the ___ while neuropeptides are synthesized in the ___.

a.      Axon terminals, cell body

9)      The pancreas is controlled by the

a.      Autonomic nervous system

10)  Skeletal muscle movement is controlled by the:

a.      Somatic nervous system

11)  Which uses norepinephrine as a neurotransmitter?

a.      Sympathetic nervous system