test #2 Flashcards
Eyespot
photoreceptor cells over a lining of screen pigment cells.
no lens, provides info about surrounding black/white, but no detail.
Simple eye
similar to the eyespot + refracting lens and some kind of an image.
for pattern recognition and locomotion.
Vertebrate eye
elaboration of the simple eye. adds a small variable aperture + a lens.
Ommatidia
The compound eyes of arthropods are image-forming eyes composed of many units.
takes in about 2-3 degrees.
cornea
outer cover
Retina
inner wall of the eye
Aqueous humor
A watery solution that fills the anterior chamber help focus the image on the retina
Vitreous humor
A jelly like solution that fills the posterior cavity
help focus the image on the retina
Pigment epithelium
Stores vitamin A1 and produces light-absorbing molecules
fovea
Part of the macula
An area of the retina that receives the center of the image axis and is rich in cones to allow distinction of small detail and colors.
Binocular convergence
The ability of both eyes to focus on the same object, enhancing 3-d vision.
Visible light
Violet light (400nm) to red light (700nm)
Photoreceptor cells
__________ initiate the response light and transmit the signal to afferent neurons as neurotransmitters.
Outer segment
contains stacks of membranes with receptor molecules
positioned AWAY from incoming light
connected to the inner seg. by cillium
Inner segment
contains the nucleus and organelles and releases neurotransmitters.
connected to the outer seg. by cillium
Rods
light sensitive
processes achromatic vision with lower resolution
Cones
less light sensitive
process color vision with higher resolution
Light is on
dark Na+ current channels close.
hyper polarization of the photoreceptor cell membrane.
Light is off
Steady inward iNa (dark current)
resting photoreceptor cell membrane potential.
Light
_____ acts as a negative stimulus
Electroretinogram
The sum of the responses from different cell types to light
What is happening in b wave?
electrical activity
What is happening in a wave?
hyper polarization of photoreceptor cells
What is happening in c wave?
Appears to be from pigment epithelial cells.
Rhodopsins
a family of transmembrane proteins in the outer segment of photoreceptor cells.
Opsin
a polypeptide (part of rhodopsin)
Retinal
a light absorbing molecule
part of rhodopsin
Opsin
Sensitivities of the cone receptors to different light depend on
Visible light, all trans
_______ changes the conformation of retinal from 11-cis to ____.
Metarhodopsin
all-trans separate retinal from rhodopsin, which then becomes______________.
Transduction
________ (g protein) activates a phosphodiesterase, which breaks cGMP —>gNa
Action Spectrum
magnitude of a photoreceptors response to different wavelengths.
Rods
____ are 10 times more sensitive to light then cones.
Primordial arc system
a single cell that serves as afferent
sensory neuron and effector neuron (“sensing effector”).
if the osmolarity of blood plasma or extracellular fluids
decrease
the cell swells and stretch-inactivated Na+ channels close, causing a decrease in the release of antidiuretic hormone (ADH)
if osmolarity increases
the cell loses water and shrinks, the
membrane becomes depolarized, and ADH release is
stimulated
channels open
Monosynaptic
separate neurons for sensory and motor
functions, but no interneurons
Polysynaptic
interneuron(s) moderate central processing.
Hydra nervous system
nerve nets, but no CNS
Sea star nervous system
nerve ring and radial nerves, no cephalization
Flatworms and round worms
segmented pattern, CNS and cephalization
cephalization
is the coalescence of neurons in the anterior
end of the nervous system (the brain)
nerve cord
bundles of
neurons (homologous
to the spinal cord in
vertebrates)
ganglion
cluster of somata
(somata in most animals
tend to be clustered)
connectives
axons between ganglia
nuclei (in vertebre)
clusters of
somata with similar
functions within
the CNS
ganglia (in vertebre)
clusters
of somata outside
the brain and
spinal cord
dorsal root
the somata of sensory neurons are clustered in the ___
dorsal horn of the gray matter
the somata of interneurons are clustered in the _____
ventral horn of the gray matter
the somata of motor neurons are clustered in the ___
ventral root
axons from motor neurons exit the spinal cord through
_____
forebrain (prosencephalon) midbrain (mesencephalon) and hindbrain (rhombencephalon)
___, ___, ___, are primary vesicles of the CNS.
___, ___, are secondary vesicles of the forebrain
telencephalon and diencephalon
___, is a secondary vesicles of the midbrain
mesencephalon
___, ___, are secondary vesicles of the hindbrain
metencephalon and myelencephalon
___, is the adult structures of the telencephalon
cerebrum
___ and __ are adult structures of the diencephalon
Thalamus and hypothalamus
___, is the adult structures of the mesencephalon
tectum
lower invertebrates
___ and __ are adult structures of the metencephalon
pons and cerebellum
___ and __ are adult structures of the myelencephalon
medula and oblongata
Medulla
Action
mediates respiration and autonomic functions
receives and relays sensory and motor information
Cerebellum
Action
receives and integrates sensory information from the
semicircular canals, and joins the visual and auditory
systems
coordinates motor outputs related to position, posture, and
orientation in space
pons (in higher vertebrates)
Action
contains tracts that connect
the medulla and the cerebellum with higher centers
Tectum (optic lobe)
Action
receives and integrates visual, auditory, and tactile inputs
these functions have been taken over by the cerebral cortex
in higher vertebrates
Cerebral cortex
the folds in higher vertebrates increase the surface area and
the number of neurons
processes sensory and motor information and association
(intelligence)
it is most elaborated in humans and primates
the hippocampus
___ assists in the
storage of long term memory related to spatial navigation
(limbic system)
Amygdala & Hypothalamus
action
process information and organize outputs related to emotions
are the centers of visceral functions and emotional responses
the hypothalamus also control water and electrolyte balance,
and the secretory activities of the pituitary gland
Thalamus
action
a major coordinating center for sensory and motor signaling
receives sensory information and relays it to the cortex
receives motor information from the cortex and relays it to
the motor centers
visceral and involuntary
The two branches of the autonomic nervous system control
____ and ___ functions.
What does Sympathetic system do?
increases heartbeat rate pupillary dilation inhibits exocrine secretion increase in blood flow to skeletal muscles
What does Parasympathetic system do?
decreases heartbeat rate pupillary constriction stimulates exocrine secretion increase housekeeping functions (like digestion)
autonomic reflex arc
The parasympathetic autonomous nervous system is also
based on the _____
the motor outputs do not pass through ____
the sympathetic chain
ganglia
the synapses between the pre- and post- ganglionic neurons
occur at ______ ganglia, or ____ organs
peripheral
target
all preganglionic neurons originate from___
and extend into the _____, parallel to the
vertebral column
spinal cord and sympathetic chain
parasympathetic, preganglionic neurons originate only from the__
head area
(through cranial nerves) and from the sacral spinal cord
parasympathetic, preganglionic neurons synapse onto ___
postganglionic neurons (usually short) near the target organs, or at peripheral ganglia
preganglionic neurons are cholinergic, which means
they all use acetylcholine as neurotransmitter
postganglionic neurons in the parasympathetic division are
are ___
use acetylcholine as neurotransmitter
postganglionic neurons in the sympathetic division are
are ___
are adrenergic
they use norepinephrine as NT
Autocrine
the cell responds to its own secreted signals.
Paracrine
the secreted signals reach only the neighboring
cells.
Synaptic
(a special type of paracrine signaling): the signal (a
neurotransmitter) is secreted by a neuron into a synapse.
The target is a specific cell.
Endocrine
the signals (hormones) can enter the bloodstream and reach distant target cells.
Neuroendocrine
the signal (a neurohormone) is secreted by a neuron into the bloodstream.
Exocrine
the signals are released from the skin or from the
lining of the gut.
synthesis of secreted proteins occurs in the ___ ____
endoplasmic reticulum
at the trans-Golgi network, protein are ___ and ___
sorted and distributed
exocytosis
protein secretion
ions are released by secretory cells into the ___
acinus (the blind
cavity that is lined by the secretory epithelium)
the negatively charged sialic acids at the ends of some oligosaccharides give the structure an overall \_\_\_\_\_ charge, which are \_\_\_\_ by high concentrations of Ca2+
negative and neutralized
Describe Secretion by endocrine glands
ductless glands
the water-soluble secretions are releases directly into the
bloodstream by exocytosis of secretory vesicles
lipid-soluble secretions can diffuse through the plasma
membrane
Constitutive secretion
proteins are secreted
right after they are sorted from the trans-Golgi network
Regulated secretion
only in specialized cells
proteins are stored in special secretory
vesicles and are released from the cell by exocytosis only
in response to external signals
the depolarization of the membrane and the increase in Ca2+ permeability causes ____
inflow of Ca2+
in simple endocrine cells, external signals cause the opening of ____
intracellular Ca2+ stores
Glands secrete:
exocrine
paracrine
endocrine
Neuroendocrine systems secrete
regulate hormone secretion from some endocrine glands
Describe hormone features
secreted by specialized tissues
secreted into the bloodstream to target tissue(s)
modulate the activity of the target tissues/organs
Hormone functions:
maintenance of blood osmolarity (antidiuretic hormone)
maintenance of blood sugar levels (insulin, glucagon)
regulation of metabolic rates (growth hormones, thyroxine)
control of behavior (epinephrine)
control of reproductive cycles and sexual activity (sex
hormones)
what does short loop negative feedback do?
the accumulation of the
hormone, or the product of the hormone’s direct target,
stops hormone secretion
what does long loop negative feedback do?
the product of an effector
series stops hormone secretion
what does positive feedback do?
the hormone’s direct target tissue
stimulates additional hormone production
no feedback regulation:
open loop
Fast responses of hormones
depend exclusively on existing cellular components
their effects are usually transient
slow responses of hormones
depend on the modulation gene expression:
a component of the cascade needs to be synthesized, or:
the modulation of gene expression itself is the response
their effects are usually long lasting
the Lipid-insoluble hormone signal is ___inside the cell
transduced
Lipid-soluble hormones are (diffused) transported in the bloodstream
as _____ and bind to
___
water-soluble protein complexes and
intracellular receptors
Second messengers synthesized in response to hormones
Cyclic nucleotides:
cAMP and cGMP
Second messengers synthesized in response to hormones
Inositol phospholipids:
DAG and IP3
What is the result when receptor (s) which bind stimulatory and inhibitory hormones respectively.
the activation (or inactivation) of adenylate cyclase, and the increase (or decrease) in cytoplasmic cAMP levels.
cAMP activates Protein Kinase A
(PKA) by binding to its ____subunits and causing the release of the ___ subunits.
regulatory
catalytic
The kinase activity of the released catalytic subunits ____ multiple effector proteins.
phosphorylate
Transient effects of PKA activation in anticipation
of muscular activity
In response to epinephrine:
converts glycogen into glucose 1-phosphate
and
inactivating glycogen synthase
PLC is activated by a _____
G protein
A single hormone can activate two signaling pathways that
result in
independent effects.
and/or
in the same effect
Amines
amino acid-derived
Eicosenoids:
derived from arachidonic acid
Steroids:
synthesized from cholesterol
Peptide hormones
amino acid chains (the largest and most
complex group)
Autacoid hormones:
active substances not included in
the above categories (serotonin, histamine)
The neurosecretory cells release
____into ____
neurohormones into capillaries:
the bloodstream carries the signal (neurohormones) to a target endocrine tissue,
which_________________
secretes a hormone that
targets another organ, or (its rarer) directly targets an organ.
Endocrine and neuroendocrine systems in the pituitary gland
Adenohypophysis (anterior lobe)
Neurohypophysis (posterior lobe)
Endocrine and neuroendocrine systems in the hypothalamus gland
contains soma of neurosecretory cells
part of the diencephalon (the posterior region of the
forebrain)
contributes to the control of the autonomic nervous system
Adenohypophysis (anterior lobe):
non-neuronal tissue
endocrine
Neurohypophysis (posterior lobe):
extension of the brain; neuronal tissue (neuroendocrine)
para intermedia
in lower vertebrates only
In vertebrates, the master gland of the endocrine system is the _________
pituitary gland
neurosecretory cells terminate ___
median eminence
portal vessels carry their signals to the ____ and respond by secreting ____
adenohypophysis, hormones.
What do Releasing hormones (RHs) or
release inhibiting hormones (RIHs) do?
stimulate or inhibit the release
of adenohypophyseal
hormones
Tropic hormones
act on other endocrine tissues to stimulate hormone production
examples of Tropic hormones
gonadotrophins: LH and TSH
Non-tropic:
act on nonendocrine tissues to modulate metabolism and other cellular functions
examples of non-trophic
MSH and growth hormone
Antidiuretic hormone (ADH):
promotes water retention
by the kidney.
Oxytocin:
promotes uterine
contractions during
childbirth and the release of
milk from mammary glands.
Metabolic and developmental hormones:
Catecholamines Glucocorticoids Thyroid hormones Pancreatic hormones Growth hormone
Hormones that regulate water and electrolyte balance:
Parathyroid hormone
Calcitonin
Mineralocorticoids
What is the source of Catecholamines
adrenal medulla
What is the source of Glucocorticoids
adrenal cortex
What is the source of Thyroid hormones
thyroid gland
What is the source of Pancreatic hormones
pancreas
What is the source of Growth hormone
adenohypophysis
What is the source of Parathyroid hormone
parathyroid gland
What is the source of Calcitonin
thyroid gland
What is the source of Mineralocorticoids
various tissues
What is the function of Catecholamines
fight-or flight reaction
What is the function of Glucocorticoids
circadian adaptation to long-term stress
What is the function of Thyroid hormones
increase metabolic rate
What is the function of Pancreatic hormones
regulate blood sugar levels
What is the function of Calcitonin
decrease blood Ca2+
What is the function of Mineralocorticoids
stimulate retention of Na+
What is the function of Growth hormone
stimulates tissue growth, fatty acid consumption
What is the function of Parathyroid hormone
increase blood Ca2+
adrenal medulla produces
catecholamines
adrenal cortex produces
glucocorticoids
catecholamines regulate
smooth muscle contractions and cardiac activity
regulates stress responses
catecholamines function as ____ when released by ____.
neurotransmitters when released by adrenergic neurons
The sympathetic nervous system
regulates the _______ response
fight-or-flight
a1 adrenoreceptors stimulate
smooth muscle contraction
sarcomere contraction
b1 and b2 adrenoreceptors activate
both activate adenylate cyclase (AC) effect: increase in cAMP, the activation of PKA, and the stimulation of glycogen breakdown
sympathetic regulation of digestion express what kind of receptor?
inhibitory a2 adrenoreceptors.
a2 adrenoreceptors cause
inhibition of AC
activity and inhibit the release
of norepinephrine from
adrenergic neurons
Other effects of b1 adrenoreceptors
are stimulated mostly by neuronal norepinephrine
cause the release of Ca2+ from the ER and an increase in cardiac activity
stimulates the release of fats from adipose tissue
Other effects of b2 adrenoreceptors
stimulated mostly by circulating catecholamines
mediate bronchiodilatation and vasodilatation
activate Ca2+ pumps, resulting in a decrease cytoplasmic Ca2+ levels
effect: smooth muscle relaxation
neurohormones from hypothalamic neurosecretory cells induce \_\_\_\_\_ production in the \_\_\_\_ lobe of the pituitary gland (adenohypophysis)
hormone
anterior
ACTH
adrenocorticotropic hormone
stimulates glucocorticoid production at the adrenal cortex
ACTH effects:
adaptation to long term stress (raise blood glucose levels, mobilize fat)
ACTH subject to
negative feedback regulation: glucocorticoids stop the secretion of ACTH and CRH
Thyroid hormones
derived from the amino acid tyrosine.
secreted by the thyroid gland for heat generation
lipid soluble
activate intracellular receptors that induce the
expression of genes that code for metabolic enzymes
results: increase metabolic rate at the liver, heart, kidneys, skeletal muscles, and nervous system–> heat generation
TRH _____ the production of ____ hormone
induces
thyroid-stimulating
A dietary iodine deficiency may result in the __________________
excessive stimulation of the thyroid gland and abnormal growth.
What are some effects of Parathyroid hormone ?
mobilizes the release of calcium and phosphate (PO43-) from bones increases calcium reabsorption from urine in the kidneys stimulates the kidneys to activate vitamin D, which promotes the intestinal uptake of Ca2+ from food increase in the levels of blood Ca2+
Calcitonin has the ability to _____ blood calcium levels by effecting two target organs; _____ and ___
decrease
kidneys and bones
Osteoclast
a cell that nibbles at and breaks down bone and is responsible for bone resorption. Osteoclasts are large multinucleate cells that differentiate from macrophages.
effect of insulin:
decrease in blood glucose
Type I diabetes:
decreased insulin production in the pancreas
Type II diabetes:
reduced insulin sensitivity at the target tissues
insulin resistance
Glucagon
secreted by pancreatic a cells in response to low blood glucose (hypoglycemia)
Glucagon inhibits
glucose uptake and glycogenesis in the liver
Glucagon stimulates
stimulates glycogenolysis in the liver; and as glucose is
released and blood glucose levels increase:
stimulates pancreatic b cells to produce insulin
GRH stimulates the release of _____
growth hormone
GH inhibits
uptake of glucose by most tissues
GH stimulates
fat cells to release fatty acids and the release of glucose from the liver
hypothalamic gonadotropin-releasing hormone (GnRH, a peptide hormone) stimulates the secretion of
luteinizing hormone (LH, a peptide hormone) and follicle-stimulating hormone
LH stimulates the production of______
testosterone in Lydig cells (in the testes)
FSH stimulates the production of ____
inhibin (a peptide hormone) in Sertoli cells (also in the testes)
Muscle fibers develop from
the fusion of myoblasts during myogenesis
satellite cells
stem cells that are arrested in G0
M line
contains enzymes for muscle energy metabolism
H zone:
myosin only
A band:
zone where actin and myosin are visible
I bands:
portions between A bands (actin and actinin)
cross bridges:
regions where myosin heads interact with actin filaments
Titin
very large protein (3000 kd)
extends from M line to the Z disc
thought to act like springs that keep the myosin filaments
centered in the sarcomere and maintain the resting tension
that allows a muscle to snap back if overextended
Nebulin
filaments associated with actin
thought to act as regulators of F-actin assembly and length
Heavy chains
two supercoiled a helices that terminate in the
amino heads.
Light chains
essential myosin light chain (dark blue) and
regulatory myosin light chain (light blue).
Tension
a reaction force applied by a stretched object on the objects which stretch it.
Isometric
energy is spent and force is generated but the
muscle is not allowed to contract
Isotonic
as force is generated the muscle contracts
the muscle does work
Momentum
the quantity of motion of a moving body,
measured as the product of its mass and velocity.
Force
an influence that may cause an object to accelerate
(increase its momentum), measured as the product of the
mass of the object and acceleration.
Work:
the exertion of force to overcome resistance. Can only
happen with isotonic contraction.
Power:
the rate at which work is performed.
Tropomyosin
long filamentous protein that binds F-actin lengthwise
If no Ca2+ is present on tnC
tropomyosin blocks the binding sites of myosin on actin
tnT binds:
binds tropomyosin
tnI binds:
binds actin and tnC
when ATP is added in the experiments :
the tension exerted by the myofibril does not increase
when Ca2+ added the experiments :
the tension exerted by the myofibril increases
Cytosolic calcium is necessary for ___ contraction
muscle
the tension exerted by the fiber in the presence of Ca2+
increases only when ___ is added
ATP
if ATP is removed while Ca2+ is still present:
no drop in the tension exerted by the fiber
if ATP is added when Ca2+ is not available:
the tension exerted by the fiber drops
what happens After a short latency period following the AP:
muscle tension increases briefly (a twitch).
muscle tension increases briefly (a twitch).
a tension transducer measures ___
force
a stimulating electrode transmits a _______
stimulus current
the resulting voltage changes are detected by the _______
recording electrode
During the latent period there is an increase in ________
cytoplasmic calcium
T-tubules:
extensions of the cell membrane that extend into
the cell and run around the perimeter of the myofibrils and
over the Z-discs.
Sarcoplasmic reticulum:
the endoplasmic reticulum of the
muscle fibers, which sequesters and stores Ca2+.
Ca2+ pumps use ATP to sequester Ca2+ into the _____ of the SR
lumen
inside the SR, Ca2+ binds _____, reducing the gradient of free Ca2+ across the SR membrane
calsequestrin
Dihydropyridine (DHP) receptors:
voltage-activated membrane proteins of the T-tubule.
Ryanodine (Ry) receptors:
Ca2+ channels* on the SR.
The depolarization of the T-tubule membrane induces a
_____________ in the DHP receptor that induces
the Ry receptor to ___.
conformation change
open
Ca2+ is released from the SR to the cytosol and binds TnC,
causing ______
sarcomere contraction
when the depolarizing stimulus stops,
Ca2+ is re-sequestered into the SR and the muscle relaxes
Slow generation:
aerobic respiration and oxidative phosphorylation
requires O2
Fast generation (during periods of intense demand):
anaerobic glycolysis (generates lactic acid)
direct phosphorylation: the transfer of a P from creatine
phosphate to ADP both are O2-independent
Antagonistic pairs in vertebrate skeletal muscles:
flexor and extensor
flexor:
a muscle that pulls a joint and causes it to close
extensor:
a muscle that opposes the flexor to open the joint
Motor pool:
a group of neurons that innervates a muscle.
Motor unit:
a motor neuron and the muscle fibers it
innervates
the length and the strength of a sustained contraction
depends on the _______
frequency of APs
