Exam 4 Flashcards
Plants and animals are multicellular organisms, what do they share in common
(Things to think about: what does it mean to be multicellular organisms, what must
they do, what makes them different than colonies of cells)
They must exchange materials with their environments. Exchanges ultimately occur at the cellular level by crossing the plasma membrane cell differentiation
Explain the potential reasons why archosaurs became dominant in the Triassic
Period
Dinosaur evolution in the Triassic:
Adaptations to lower oxygen levels
Bipedalism
Four chambered heart
One Lung
Explain the factors that limit the size of arthropods.
Open circulatory system
The tracheal tubes supply O2
directly to body cells.
Relies mostly on diffusion. The respiratory and circulatory systems are separate Larger insects must ventilate their tracheal system to meet O2 demands
These separate systems and a reliance of diffusion places limits on the size of arthropods
Explain how a one-way lung works differently than a two-way lung.
On the first breath, air moves into the air sac. First breath out, air moves into lungs. Second breath in, air moves into from air sac. Second breath out, air leaves the body.
Explain how counter-current exchange maximizes oxygen absorption. What would
happen if the blood flow was in the same direction as water flow
Blood flows in the opposite direction to
water passing over the gills. Oxygen diffuses into the blood.Because the blood is moving in the opposite direction as the water flow,The blood as the highest amount of oxygen, but so does the water. Because the water has a higher amount of oxygen, it will diffuse into the blood. How Gills Work in Vertebrates If the blood flow was in the same direction, a concentration gradient couldn’t be established.
Explain how a shark can drown.
It turns out that most sharks move water across their gills by a process known as ram ventilation.
They constantly swim to move water across their gills.
If they stop swimming, then they will drown because they cannot move water across their gills.
Why do we think jaws evolved in vertebrates?
In jawed fish (sharks, bony fish, and all terrestrial
vertebrates, including humans),
the jaws evolved from the gill arch. This was likely to
increase water flow across the gill.
Luckily, it also helped them increase the number and
types of prey they could catch.
Name other organisms that use gills in addition to fish.
Freshwater insects
Freshwater crawfish
Explain the difference between cellular respiration and respiration as it applies to
physiology.
Physiology
* The movement of oxygen from the
outside environment to the cells
within tissues and the removal of
carbon dioxide
* The diffusion and transport of oxygen
and carbon dioxide (metabolites)
between the organism and the
external environment
Cellular respiration
* The oxidation of organic molecules,
usually with oxygen to make ATP.
* A metabolic reaction that takes place
inside cells to make ATP and remove
waste.
* Aerobic respiration uses oxygen to
make ATP.
* Anaerobic respiration doesn’t use
oxygen, but other electron acceptors
* Fermentation – extracting energy in
the absence of oxygen
Describe the functions of the sympathetic and parasympathetic nervous system.
Sympathetic: Regulates arousal and energy
generation
* (“fight-or-flight” response)
Parasympathetic: Rest
* Relaxes your body after stress and
danger
* (“rest and relaxation” response)
List the four major structures of the brain and describe their functions.
Cerebrum
structure responsible for
higher mental functions
Diencephalon
* processing, integrating, and relaying
information to different parts of
brain,
* homeostatic functions,
* regulation of movement,
* and biological rhythms
Cerebellum
* planning and coordination of
movement,
* especially complex activities
such as playing a sport or an
instrument
Brainstem
* basic involuntary
homeostatic functions
* Control of certain reflexes
* Monitoring movement
* Integrating and relaying
information to other parts
of nervous system
Describe the differences between the afferent and efferent divisions of the PNS
Afferent: sensory, going to brain.
Efferent” motor, going from brain.
Describe the differences between the PNS and the CNS
CNS is brain and spinal cord. PNS: cranial nerves, spinal nerves, and branches.
The PNS transmits information to and
from the CNS and regulates
movement and the internal
environment.
List the 6 types of neuroglia
4 types reside in CNS:
* Astrocytes
* Oligodendrocytes
* Microglia
* Ependymal cells
* 2 types reside in PNS:
* Schwann cells
* Satellite cells
Explain how a nerve signal is transmitted down the axon of a neuron.
A neuron at resting potential (-60mv) receives a signal. If it crosses the threshold depolarization begins. Voltage gated ions open, sodium specifically, moving into cell axon. Inside is now positive and depolarized. Na + flows in, sodium flows in. Repolarization occurs, K+ channels open and potassium flows out. The cell is negative and is in refractory for awhile.
Beginning with the release of the neurotransmitter acetylcholine, explain how a
muscle cell contracts using the sliding filament theory.
AP arriving at motor neuron causes Ca2+ channels to open, triggering excitosis of synaptic vessels and Ach release. Ach diffuses across synaptic cleft and binds to ligand gated channels in motor end plate. The channels open, Na+ enters muscle fiber creating the end plate potential. AP triggered. Chain reaction occurs down muscle fiber to triads. Terminal cisternae release calcium into cytosol which bind to troponin and expose actin. Myosin cross bridge attaches, power stroke occurs as atp becomes adp mysoin head changes shape and pulls on actin. Can continue or stop.
Astrocytes (CNS)
Large star-shaped cells whose many processes terminate in structures called
end-feet:
* Anchor neurons and blood vessels in place; help define and
maintain three-dimensional structure of brain
* Facilitate transport of nutrients and gases between blood
vessels and neurons; regulate extracellular environment of
brain
* Assist in formation of blood-brain barrier; protective
structure that surrounds capillary endothelial cells and
makes them impenetrable to most polar compounds and
proteins
* Repair damaged brain tissue by rapid cell division
Oligodendrocytes (CNS)
Myelin sheaths
Radiating processes with
flattened sacs wrap around
axons of nearby neurons to form
myelin
Microglia (CNS)
Small and scarce cells;
activated by injury into wandering
phagocytic cells within CNS;
ingest disease-causing
microorganisms, dead neurons,
and cellular debris
Ependymal cells (CNS)
ciliated cells that line hollow spaces found
within CNS (brain and spinal cord);
manufacture and circulate cerebrospinal fluid
Satellite cells (PNS)
found surrounding cell bodies of
neurons in PNS to provide
supportive functions
(still not well defined)
Schwann cells (PNS)
encircle axons found in
PNS to provide them
with myelination
