Biology-Animal Form and Function 2 Flashcards
Liver Functions
Vitamin Storage
stores vit A, D, B12.Also stores iron by combining it with apoferritin => ferritin
Portal vein
all carbs absorbed into blood are carried by portal vein to the liver
Liver Function
Glycogenesis
formation of glycogen
Liver Function
Glycogenolysis
if blood glucose levels decrease => glycogen is broken down to glu for release
Liver Function
What happens to blood acidity, when the liver mobilizes fat or protein for energy?
blood acidity increase (ketone bodies are produced => ketosis/acidosis results)
Liver Function
Blood supply
hepatic portal vein supplies blood as does hepatic artery (oxygenates liver); blood leaves via hepatic vein => vena cava
Liver Function
Digestive and Transport
Digestive: produces bile
Transport: synthesizes blood plasma proteins important in clotting
Nervous System
Neuron vs. Endocrine
neuronal communication is rapid/direct/specific. Hormonal is slower/spread through body/affects many cells/tissues in different ways/longer lasting
Nervous System
Neuron
consists of several dendrites, single (branched) axon, and cell body
Nervous System
Dendrites
receive information and transfer it TO cell body
Nervous System
Axon
transfers impulses AWAY from cell body
Nervous System
Glial Cells
nervous tissue support cells; capable of cellular division
- **oligodendrocytes **produce myelin in CNS; wrap many times around axons
-
schwann cells produce myelin in PNS. Myelin sheaths act as insulators and are separated by **nodes of Ranvier. Intead of traveling continuously down axon, action potential jumps from node to node (salutatory conduction**), speeding up impulse
- only vertebrates have myelinated axons. Myelinated axons appear white (white matter); neuronal cell bodies gray (gray matter)
- other glial cells include: microglia (phagocytes of the CNS), ependymal (use cilia to circulate CSF), satellite cells (support ganglia- groups of cell bodies in PNS), and astrocytes (physical support to neurons of CNS; maintain mineral and nutrient balance
Nervous System
3 Types of Neurons
- **Sensory (afferent) **receive initial stimulus (Ex. neurons in retina of eye) A => BRAIN
- **Motor (Efferent) **stimulate effectors, target cells that elicit some response (Ex. neurons may stimulate the muscles, sweat glands, or cells in stomach to secrete gastrin.) BRAIN => M
- Association (Interneuron)- located in spinal cord and brain - receive impulses from sensory and send impulses to motor neurons. They are integrators, as they evaluate impulses for appropriate response. ~99% of nerves are interneurons
Nervous System
Transmission of a Nerve Impulse (Unstimulated Neuron)
the membrane of an unstimulated neuron is polarized, although a high [Na+] is present outside of cell and a high [K+] is present inside the cell (the inside is actually negative due to the negatively charged proteins and nucleic acids residing in the cell). Additionally, neuron membranes are selectively permeable to K+ as opposed to Na+, which helps to maintain the polarization
Nervous System
Transmission of a Nerve Impulse
- Resting Potential- normal polarized state of neuron, -70 mV
- Action Potential- stimulus => gated ion channels let Na+ into cell, depolarizing it. If the threshold level is reached (~-50mV), it will cause an action potential that will result in opening of (voltage gated) Na+ channels down the entire length of the neuron. All or nothing event!
- **Repolarization- **in response to Na+ flow in, more gated ion channels let K+ out of the cell, restoring polarization-but the Na+ are IN and the K+ are OUT
- **Hyperpolarization **By the time the channels close, too much K+ is released (-80 millivolts)
- **Refractory period **Neuron will NOT respond to new stimulus until Na+/K+ pumps return the ions to their resting potential locations (outside/in, respectively) if absolute. If relative, abnormally large stimuli can create an AP. Note that refractory period is what prevents an AP from moving backwards, even though ions are theoretically rushing in and diffusing in both directions
Nervous System
Transmission of Nerve Impulse NOTE
from -70 up to threshold (or -70 downward) is the **graded potential **that cannot travel, but it can potentially (if it surpasses threshold) open the voltage gated channels and this part is the action potential that travels by opening other voltage gated. The other gated types cannot spread unless they trigger this AP. Also note that AP is all or nothing, so strength of a neural signal is based on other factors (frequency of AP firing or how many neuron cells contribute AP’s, etc).
Nervous System
Transmission across synapse
presynaptic cell => postsynaptic cell
I. Electrical- action potential travels along membranes of gap junctions (less common); fast; cardiac and visceral smooth muscle
II. Chemical- most typical in animal cells; unidirectional (unlike electrical)
- Ca2+ gates open- depolarization allows Ca2+ to enter cell
- Synaptic vessels release neurotransmitter- influx causes release into cleft
- Neurotransmitter binds with postsynaptic receptors. Diffusion (via Brownian motion) and binding
- **Postsynaptic membrane is excited or inhibited. **Two possible outcomes:
- Na+ gates open, membrane is depolarized => excitatory postsynaptic potential (EPSP), if threshold potential is succeeded, action potential is generated
- K+ gates open, membrane becomes hyperpolarized => inhibitory postsynaptic potential (IPSP)…it becomes more difficult to generate action potential
- Neurotransmitter is degraded and recycled. Broken down by enzymes in cleft and recycled.
Nervous System
Acetylcholine (neurotransmitter)
secreted at neuromuscular junctions (gaps between motor neurons and muscle cells) => muscle contraction/relaxtion. Inhibitory everywhere else.
a. parasympathetic nervous system
Nervous System: Neurotransmitters
Epinephrine, norepinephrine, dopamine, and serotonin (5HT)
AA derived, secreted between neurons of CNS
a. sympathetic nervous system
Nervous System: Neurotransmitter
Gamma aminobutyric acid (GABA)
inhibitory neurotransmitter among brain neurons
Nervous System
Diameter and mylineated axons
Greater diameter and more heavily myelinated axons will propagate faster impulses (greater diameter because less resistance to “flow” of ions- think water through a large pipe vs. a small one, and myelinated because of saltatory conduction; the Na doesn’t gradually defuse outward [charge leakage] at every successive AP requiring new Na to rush in to keep the impulse going; it can’t leak out of myelin wrapped sections so it drives straight from node to node
Nervous System
Synaptic vesicles
synaptic vessels fuse w/ presynaptic membrane => neurotransmitter => postsynaptic
Nervous System
Neurotransmitter
may be taken back into nerve terminal (active transport), degraded synaptic clef enzymes (recycle back to presyn), or diffuse out of the synapse
Central Nervous System
Central Nervous System consists of what two parts?
Brain and spinal cord
Central Nervous System
Brain
outer grey matter (cell bodies) and inner white matter (axons);
- forebrain largest/most important brain region. Contains cerebral cortex (processes sensory input/ important for memory and creative thought), olfactory bulb (smell), **thalamus **(relay for spinal cord and cerebral cortex), hypothalamus visceral function (water balance, blood pressure, and temp. regulation, hunger, thirst, sex)
- **midbrain **relay center for visual/ auditory impulses; motor control
- **hindbrain **posterior part of brain; cerebellum (maintainence of balance, hand-eye coord, timing of rapid movements), pons (relay center to allow communication b/w cortex and cerebellum), medulla oblongata (breathing, heart rate, gastrointestinal activity)
- brainstem consists of midbrain + medulla oblongata + pons. Connects the cerebrum with the spinal cord
Central Nervous System
Cerebrum
largest part of brain w/ two hemispheres connected by corpus callosum (thick nerve bundle); contains sensory, motor, association areas
- Divided by lobes:
- frontal (conscious thought; voluntary skeletal muscle movement)
- partietal (sensory areas-temperature, touch, pressure, pain)
- temporal (sensory-hearing and smelling)
- occipital (sensory-vision)
- has outer portion (cerebral cortex- gray matter
- inner portion (medulla-white matter)
Peripheral Nervous System
Peripheral Nervous System (PNS)
consists of sensory branch and motor branch. Motor consists of somatic and autonomic nervous systems:
- **somatic **responsible for VOLUNTARY movement of skeletal muscles
- **autonomic **involuntary movement; innervates cardiac and smooth muscle
- sympathetic- flight or flight (higher BP and HR)
- Parasympathtic- rest and digest; non-emergency (lower HR, digestion, relaxation, and sexual arousal)
Reflex Arc
rapid, involuntary response to stimulus involving 2 to 3 neurons, but brain DOES NOT integrate the sensory and motor activities…instead synapse in spinal cord.
ex. knee-jerk (patellar) reflex
Sensory Receptors
- mechanoreceptors (touch)
- thermoreceptors (temperature)
- nociceptors (pain
- electromagnetic receptors (light)
- chemoreceptors (taste, smell, blood chemistry)
respond strongly to own stimuli, weak to others; neural pathways separate + terminate in CNS
*all nerves not directly inside the brain or spinal cord are all part PNS. Cranial and spinal nerves come OUT of those structures and are part of PNS
Eye
Eye
**cornea **(focuses light) => **pupil **(diameter controlled by iris {pigmented})=> **lens **(controlled by ciliary muscles; focuses img) => **retina **(light sensitive cells)
Eye
cones
high-intensity illumination; sensitive to color
Eye
Rods
low intensity; important in night vision; no color
- Rhodopsin (rod pigment) is struck by photons from light, causing hypolarization transduced into neurl AP sent to brain
- photoreceptor cells synapse to bipolar cells => ganglion cells => axions of ganglion cells bundle to optic nerve
- point at which optic nerve exits is blind spot (no photoreceptors there)
Eye
Fovea
densely packed with cones; important for high acuity vision
Eye
Vitrous Humor
Aqueous Humor
(jelly like, maintains eye shape and optical properties)
(anterior chamber, eye produces it)
Eye
Eye disorders
- myopia-nearsightedness
- hyperopia-farsightedness
- astigmatism-irregularly shaped cornea
- cataracts-lens becomes opaque => light cannot enter
- glaucoma- increase in pressure of eye due to blocking of outflow of acqueous humor
Ear
Ear
structure is 3 main parts: outer, middle, and inner ear; tranduces sound energy into impulses
Ear
outer ear
auricle/pinna (what we think of as the ear) and auditory canal; direct sound into external auditory canal => then goes to middle ear
Ear
middle ear
amplifies sound; tympanic membrane (eardrum) begins the middle ear and vibrates at the same frequency as incoming sound => ossicles (malleus, incus, and stapes) => inner ear
Ear
Inner Ear
wave moves through the cochlea (vibration of ossicles exert pressure on fluid). As wave moves through pressure alternates, moving the vestibular membrane in and out; this movement is detected by hair cells (not actual hair but specialized stereocilia) of the organ of Corti => transduced neural signal => action potential
- inner ear also has **semicircular canals **responsible for balance (fluid + hair cells sense orientation + motion)
Muscular System
Muscle contraction
may result in movement, stabilization of position, movement of substances throughout body, generation of body heat
