Terminology: 28-31 Flashcards
(105 cards)
1
Q
Stimulus
A
Detected change in the environment
2
Q
Sensory Receptor
A
Specialized dendrites of sensory neurons that receive specific types of stimulus.
3
Q
Sensory Pathway
A
Consists of the chain of neurons from a receptor organ to the cerebral cortex responsible for the perception of sensations.
4
Q
CNS
A
Brain and spinal cord in which sensory information is received, processed, and motor signals are outputted.
5
Q
Motor Pathway
A
A neural pathway that originates in the brain and descends down the spinal cord to control motor neurons.
6
Q
Effector
A
Cell or a group of cells that performs a specific function in response to motor signals.
7
Q
Response
A
An action triggered by stimulus.
8
Q
Bats & Moths
A
- Bats track prey through sonar.
- Some moths have evolved to detect bat sonar and take evasive action.
9
Q
Action Potential
A
The electrical mechanism through which nerve cells conduct information. When a neuron is depolarized, it triggers a wave of depolarization across adjacent cells.
- Resting potential is -70mV, stimulus disturbs the resting voltage and increases the voltage (depolarization)
- Sufficient stimulus to depolarize past the trigger threshold (-55mV) will trigger an action potential event.
- When triggered, rapid depolarization causes the membrane potential to increase and peak at +40mV. This causes other neurons to also depolarize, rippling across all adjacent neurons.
- The membrane potential then rapidly repolarizes after the peak, dipping down to -75mV. It will steadily return to its resting potential of -70mV during which it is hyperpolarized.
10
Q
Nerve Impulse
A
Action Potential
Stimulus is converted into electrical impulses.
A cascading wave of electrical depolarization across a nerve fiber terminating at the CNS.
11
Q
Sensory Transduction
A
The conversion of sensory stimulus into electrical impulses.
12
Q
Resting Membrane Potential
A
When the inside of the neuron is more negative than the outside.
-70mV
13
Q
Depolarization
A
The positive change of a cell’s membrane potential. As voltage-gated Na+ channels open:
Na+ ions flow OUT of the cell.
K+ ions flow INTO the cell.
When an action potential is triggered past the -55mV threshold, it peaks at +40mV.
The level of depolarization is proportional to the intensity of the stimulus
14
Q
Repolarization
A
The negative change of a cell’s membrane potential. Voltage-gated Na+ channels close, voltage-gated K+ channels open:
Na⁺ ions flow back INTO the cell.
K+ ions flow OUT of the cell.
After an Action Potential’s peak of +40mV, the membrane potential drops back to a negative charge.
15
Q
Hyperpolarization
A
Negatively charging a cell’s membrane potential below the resting potential of -70mV to -75mV. This induces a refractory period in which Na+ ions are filtered back out the cell until membrane potential is reset to resting potential. A neuron cannot be triggered again until it resets to resting potential.
-75mV
The level of hyperpolarization is proportional to the intensity of the stimulus
16
Q
7 Types of Sensory Receptors
A
- Nociceptors
- Thermoreceptors
- Mechanoreceptors
- Chemoreceptors
- Photoreceptors
- Electroreceptors
- Magnetoreceptors
17
Q
Nociceptors
A
Detects pain stimulus
18
Q
Thermoreceptor
A
Detects temperature stimulus
19
Q
Mechanoreceptor
A
Detects pressure changes
(e.g. hair cells of ear)
20
Q
Chemoreceptor
A
Detects changes in molecular concentrations
(e.g. CO₂, O₂, pH)
21
Q
Photoreceptor
A
Detects particular wavelengths of light
22
Q
Electroreceptor
A
Detects electrical fields
23
Q
Magnetoreceptor
A
Detects magnetic fields
24
Q
Hearing Process
A
- Sound waves are collected by the Pinna (outer ear).
- Those waves travel through the ear canal to the tympanic membrane (eardrum).
- The sound is amplified and by the ear ossicles (tiny bones).
- Air based sound is converted to liquid based sound in the cochlea, which vibrates the basilar membrane.
- Hair cells of the basilar membrane perform sensory transduction to translate the vibrations to electrical signals.
25
Pinna
The outer ear.
Made of cartilage and skin.
26
Tympanic Membrane
* Also known as the eardrum.
* A thin membrane that separates the outer ear from the middle ear.
* Transmits sound from the air to the ossicles in the middle ear.
* Also protects the middle and inner ear from pathogens and debris.
27
Cochlea
Hollow spiral bone shaped like a snail shell. It is fluid filled.
Contains the **Basilar Membrane** and the **Organ of Corti**.
28
Ear Ossicles
Tiny bones of the middle ear involved in the translation of air based sound of the outer ear to liquid based sound of the cochlea.
* Malleus
* Incus
* Stapes
29
Basilar Membrane
A membrane that separates the scala media and the scala tympani fluids within the cochlea.
The basilar membrane moves up and down in response to sound waves, which are converted to electrical signals by hair cells.
30
Oval Window
The membrane between the middle ear and the inner ear, facilitating the translation of air based sound to liquid based sound of the cochlea.
31
Hair Cells
Sensory receptors of the auditory and vestibular (balance) system.
Hair cells are afferent sensory neurons that function as mechanoreceptors.
Sound deflects the stereocilia of the cell, which triggers the release of neurotransmitters at the basal end of the cell. This neurotransmitter then induces action potentials to be generated at a nerve terminal.
32
How is Loudness & Pitch Coded?
Loudness: Louder sounds cause more hair cells to be stimulated, which is interpreted by the brain to be loud.
Frequency: The basilar membrane vibrates at different frequencies across the cochlea. The position of the stimulated hair cells within the basilar membrane determines the interpreted frequency.
33
Eyeball structure
General Layers:
1. Sclera
2. Choroid
3. Retina
Forward Structures:
1. Cornea
2. Iris & Pupil
3. Lens
34
Eyeball layers
1. Sclera
2. Choroid
3. Retina
35
Cornea
* The outermost forward structure of the eye. Transparent.
* The cornea refracts light, contributing most of the eye's focusing power (along with fluid and the lens).
* The focus of the cornea is fixed.
36
Lens
* A forward structure underneath the iris and pupil of the eye. Transparent.
* Refracts light, focusing it onto the retina.
* Can adjust the focal length of the eye, enabling it to focus on objects at varying distances.
37
Sclera
* The white outer layer of the eye.
*Protective function
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Choroid
* The middle layer of the eye.
* Provides oxygen and nourishment to the retina.
39
Retina
* The innermost layer of the eye.
* The retina contains the photoreceptor cells that detects light and converts it into electrical signals.
Layers of Retina
1. Ganglion Cells
2. Bipolar Cells
3. Photoreceptor Cells (Rods & Cones)
4. Pigmented Epithelium
40
Rod Photoreceptors
Photoreceptors of the retina that functions in dim light and provide monochromatic vision.
41
Cone Photoreceptors
Photoreceptors of the retina that functions in well-lit conditions and provides color perception.
42
Iris
A thin structure under the cornea that contains a sphincter muscle that contracts the iris to control the amount of light received by the retina.
43
Pupil
The pupil contains a muscle called the pupillary dilator that expands and contracts the pupil size.
44
Ciliary Muscle
A muscle within the choroid layer that can expand and contract the lens of the eye to adjust focus (focal length)
45
How does light effect neurotransmitters?
Light stops inhibitory neurotransmitters.
NA⁺ channels are open in darkness (depolarized)
Depolarized photoreceptors release inhibitory neurotransmitters.
NA⁺ channels are closed in light (hyperpolarized)
Post synaptic cell generates action potentials due to absence of inhibitory neurotransmitters
46
Retinal
A conjugated chromophore that changes shape upon receiving light, which activates **rhodopsin**.
47
Rhodopsin
A protein known as visual purple. It is a protein that activates the membrane protein **transducin**.
48
Transducin
A protein that activates the enzyme **phosphodiesterase (PDE)**.
49
Phosphodiesterase (PDE)
An enzyme that breaks down **cyclic guanosine monophosphate (cGMP)** to **guanosine monophosphate**.
50
Cyclic Guanosine Monophosphate (cGMP)
As cGMP levels **decline**, the **cGMP-gated sodium channels** in the plasma membranes of rod cells **close**.
51
cGMP-Gated Sodium Channels
Channels that **close** upon **declining cGMP levels**, which causes **Na⁺ intake to decrease** and the membrane potential **hyperpolarizes**, decreasing inhibitory neurotransmitter release.
52
Muscle
Composed of long & thin skeletal muscle cells.
Each skeletal muscle cell is a fiber, and a bundle of fibers is a fascicle.
53
Myofibrils
Protein filaments within muscle cells.
54
Sarcomeres
Repeating longitudinal myofibril filaments are called sarcomeres.
55
Myosin
A motor protein, thick filament that uses ATP to produce the contraction of muscles.
56
Actin
Thin structural protein that together with myosin actuates muscle movement.
Actin in muscle is twisted into double strands along with troponin and tropomyosin.
57
Troponin
A complex of three regulatory proteins that reside in the grooves between actin filaments. Is attached to the protein tropomyosin.
Binds Ca²⁺ ions and interacts with tropomyosin to expose myosin head binding sites on actin.
58
Tropomyosin
A two stranded helical protein that works in conjunction with troponin to regulate muscle contraction.
59
Flexion
Movement that decreases the angle of a limb
60
Extension
Movement that increases the angle of a limb
61
Rigor Mortis
Stiffening of the body caused by chemical changes in the myofibril of muscles which don't allow the muscles to relax. Rigor mortis occurs 4 hours after death at room temperature and lasts for 4 hours.
62
Neuromuscular Junction
The synapse between a motor neuron and a muscle cell. The neurotransmitter acetylcholine (Ach) is released at this synapse.
63
Acetylcholine (Ach)
The neurotransmitter that motor neurons release at neuromuscular junction synapses to activate muscle responses.
64
Muscle Contraction
Activation of tension generating sites within muscle cells.
65
Muscle Relaxation
Deactivation of tension generating sites within muscle cells.
66
Autocrine Signals
Chemical signals a cell secretes that binds to autocrine receptors of the same cell, causing changes in the cell.
67
Paracrine Signals
Signals a cell secretes to affect local effector cells
(e.g. insulin)
68
Endocrine Signals
Also known as hormones, produced and secreted by specialized organs called endocrine glands. Hormones are transmitted to distant effector cells through the blood.
69
Neural Signals
Neurotransmitters that diffuse a tiny distance from a presynaptic cell to a postsynaptic cell. Causes a change in membrane potential in the postsynaptic cell
(e.g. Acetylcholine or Ach)
70
Neuroendocrine Signals
Signals released by specialized neurons called neurosecretory cells. They are technically hormones because they are transmitted through blood and act on distant effector cells
(e.g. ADH)
71
Pheromone
A chemical signal released to external of an organism to affect another organism.
72
Endocrine Pathway
A pathway that transmits hormones directly from endocrine cells to effector cells
73
Neuroendocrine Pathway
A pathway that transmits neuroendocrine signals that act directly on effector cells
74
CNS-to-Endocrine Pathway
A pathway through which neuroendocrine signals stimulate cells in the endocrine system, which in turn produce an endocrine signal that acts on effector cells.
75
Three Primary Types of Hormones
1. Polypeptides: Insulin, Glucagon
2. Amino Acid Tyrosine Derived: Epinephrine
3. Steroid Lipids: Estrogen, Testosterone
* Polypeptides and Amino Acids **CANNOT** pass through plasma membrane, they can only bind to membrane receptors.
* Steroid hormones **CAN** pass through plasma membrane, so they bind to intracellular receptors.
76
Pituitary Gland
**Anterior Pituitary Gland:** A gland that regulates several physiological processes through **negative feedback** including stress, growth, reproduction, metabolism rate, and lactation.
**Posterior Pituitary Gland:** Connected to the hypothalamus and regulates hydroelectrolytic stability through ADH secretion.
77
Hypothalamus
A structure of the brain that links the nervous system to the endocrine system via the pituitary gland.
Secretes
* ADH (Anti-Diuretic Hormone): Controls blood pressure and regulates fluid volume of the body.
* Oxytocin: Induces labor contractions during childbirth. Can also be used to induce abortion.
* RH (Releasing Hormones): Produced by neurosecretory cells to stimulate anterior pituitary gland production of hormones.
78
Thyroid Gland
An endocrine gland that consists of two connected lobes.
Secretes:
79
Parathyroid Glands
* One of four glands of the thyroid
* Hormones secreted by this gland increases the calcium levels in blood
80
Adrenal glands
* Secretes steroid hormones, adrenaline, and noradrenaline
81
Islets of Langerhans
Groups of pancreatic ccells that secrete insulin and glucagon
82
Ovaries
A pair of female glands in which the eggs form and the female hormones estrogen and progesterone are secreted from.
83
Testes
An organ which produces spermatozoa (male gametes), and secretes testosterone, the principal male hormone.
84
Epinephrine
A hormone secreted by the adrenal gland that induces fight/flight response.
* Increases heart rate
* Increases blood pressure
* Increases blood glucose
* Increases free fatty acid
85
Testosterone
A hormone secreted by the testes that increases male secondary sexual characteristics.
86
Estrogen (Estradiol)
A hormone secreted by the ovaries that regulates menstrual cycles and female secondary sexual characteristics.
87
Calcitonin & Parathyroid Hormone (PTH)
Secreted by the thyroid gland. Involved in homeostasis and regulates blood Ca²⁺ levels.
88
Non-Steroid Hormones
Binds to receptors on target cell's plasma membrane. Requires Cyclic Adenosine Monophosphate (cAMP) as a secondary messenger to phosphorylate enzyme activations.
1. Binds to surface receptor
2. AC Enzyme activates
3. AC catalyzes ATP to cAMP
4. cAMP initiates signal transduction cascade **(amplification)**
89
Budding
A form of asexual reproduction in which offspring are attached to the parent, later breaking free to become independent organisms.
(e.g. Hydra)
90
Fission
Individual splits into two or more parts to become independent offspring.
(e.g. Planarians)
91
Parthenogenesis
Offspring develop from unfertilized eggs
(e.g. Lizards)
92
Dioecious Species
Species with separate male and female genders
93
Monoecious Species
Species with combined male and female individuals
94
Spermatogenesis
The production process of developing mature spermatozoa
95
Oogenesis
The production process of developing an ovum (eggs).
96
Spermatophore
A protein packet containing a mass of sperm transferred from male to female.
97
Genital Plug
A resin-like plug that male spiders insert into Females to prevent further mating from other competing males.
98
Oviparity
Laying eggs. Can produce many offspring, but more difficult to nourish and protect.
99
Viviparity
Internal development of an embryo.
Can produce very few offspring but can better protect and nourish.
100
Ovoviviparity
Eggs retained internally within the mother until hatching.
101
Puberty
1. Hypothalamus secretes **Gonadotropin Releasing Hormone (GnRH)** that acts on anterior pituitary.
2. Anterior Pituitary secretes **Follicle Stimulating Hormone (FSH)** and **Luteinizing Hormone (LH)** which are gonadotropins
3. Testes secrete **Testosterone** OR Ovaries secrete **Estrogen (Estradiol)** and **Progesterone**
102
Menstrual Cycle
Approximately 28 days long.
1. Menstruation: Breakdown and release of endometrium. Follicular & Luteal phases.
2. FSH causes a new follicle to mature, follicular cells secrete estrogen which promotes thickening of endometrium.
3. LH levels peak in mid cycle, which triggers ovulation (release of the secondary oocyte). The empty follicle transforms into a corpus luteum.
4. Corpus Luteum secretes progesterone and estrogen, further thickening endometrium.
5. Progesterone & estradiol have negative feedback effect on GnRH & FSH/LH secretion
6. Drop in LH causes degeneration of corpus luteum and a sudden drop in progesterone levels.
7. Endometrium starts to breakdown (Period).
103
Pregnancy
* Following fertilization and implantation, the placenta produces **Human Chrionic Gonadotropin (HCG), which maintains the corpus luteum.
* The corpus luteum continues to secrete progesterone and estrogen to maintain the endometrium, which supports the pregnancy.
Pregnancy tests look for HCG
104
Placental Blood Flow
Countercurrent blood flow in which the maternal blood flows opposite to the fetal blood flow. Kind of like fish gills?
105
Gestation
Nine months of gestation divided into three trimesters.
Before 2 month mark: Embryo
After 2 month mark: Fetus
