Brain and Senses Flashcards
Do you use only 10% of your brain?
No, each different activity might use 10%
Is your brain fixed for life once you’re an adult?
No, changes are constant and continuous because stem cells are present; mature neurons do not divide, but stem cells have been found in the brain
Are neurons the only nervous system cells?
No, glia/glial cells can trigger neuron activity
Is the brain gray?
No, the brain is red, black, white, and gray
Does listening to Mozart make you smarter?
No
Is it true that once your brain is full, you can’t fit anymore information in it?
Not true
Is it true that you only have one learning style?
No
Should you study in the same quiet space?
No, your brain makes more connections around sights and sounds
How many neurons are in the brain?
86 billion
How many connections do you have in your brain?
10-100 trillion
How are neurons connected?
In densely packed groups, in which the groups are connected to help form thoughts
What is the cell body/soma of a nerve cell?
Contains the neuron’s nucleus and organelles
What are dendrites?
The connections of the nerve cell that bring body information to the cell body
What is an axon?
A long extension of a nerve cell that takes information away from the cell body
What is myelin?
Coating/insulation of the axon that increases the transmission speed along the axon
Summarize nerve cell impulses:
An electrical current that travels along dendrites or axons due to ions moving through voltage-gages channels in the neuron’s plasma membrane. Uses active transport and sodium potassium pumps to sends signals. Exterior of cell is positive; interior has a negative charge —> resting potential
Are all neurons electrically excitable (difference of charge across their membrane)?
Yes
What are the 2 speeds of nerve cells?
Gray and white matter
What is gray matter?
Collections of nerve cells that do not have myelin (slower transfer, about 20 mph, at much shorter distances)
What is white matter?
Collections of nerve cells that have myelin (faster signal transfer at 200 mph to 300 mph)
Neurons are specialized to send messages to what type of cells?
Target cells (messages pass at a synapse)
What is a synapse?
Close associations that allow nerve cells to send electrical or chemical messages
A typical neuron has about how many synapses?
About 1,000 to 10,000 synapses with other neurons, muscle cells, glands, etc
Who has the most basic nervous systems?
Cnidarians (jellyfish, hydra, etc) with no brains and planaria because they have parallel nerve cords that extend to the muscles
What are the 3 parts of the vertebrate brain?
Hindbrain, midbrain, and forebrain
What does the hindbrain do?
Coordinates incoming sensory info and outgoing motor instructions. It contains centers that regulate breathing and blood circulation
What is the main part of the hindbrain?
The cerebellum – important for motor control (coordination)
What does the midbrain do?
Vision, hearing, motor control, sleep/wake, alertness, and temp. regulation
What are the parts of the forebrain?
Cerebral cortex, thalamus/hypothalamus, and hippocampus/amygdala
What does the frontal lobe control?
Movement and smell
What does the parietal lobe control?
Somatic sensation
What does the occipital lobe control?
Vision
What does the temporal lobe control?
Hearing and formation of memory (hippocampus)
What is the spinal cord?
A long, bundle of specialized nerve fibers that run from the brain to the tail
What does the spinal cord do?
Sends motor information ad receives information from the senses
What directly stimulates muscle contraction – somatic nerve (control muscles)?
Motor neurons
What does the spinal cord also control?
Automatic functions and involuntary activities (heart rate, digestion, and respiration)
How does the brain process?
Priming and context
Sensation and perception involved three steps by the sense cells and are:
Transduction, transmission, and integration
What is transduction?
Change the energy of the stimulus into electrical signals
What is transmission?
Moving the message from the receptor cell to the CNS
What is integration?
Forming mental images of the world from the sense messages (brain)
What is sound?
Pulsations of air molecules — waves of pressure
Best human ears hear around how many different tones?
340,000
What is the mammalian ear?
3 chambers – the outer ear, middle ear, and inner ear
What does the outer ear do?
Collects sound waves and channels them through the auditory canal to the tympanic membrane (eardrum) and the eardrum vibrates
What does the middle ear do?
It’s filled with air, which enters through the Eustachian tubes from the throat
What opens the Eustachian tubes to allow air pressure to equalize?
Swallowing, chewing, and yawning
What does the inner ear do?
Three small bones (malleus incus, and stapes) transmit the movement of the tympanic membrane to the inner ear. In the inner ear, sound is transferred to the cochlea and hair cells detect the motion of the fluid in the cochlea
What are other functions of hair cells?
Fish and frogs hair cells detect changes in water movements and humans’ semicircular canals determines the position of the head (moves with gravity)
What are photoreceptors?
Specialized light-sensitive cells that convert the light image into electrical signals that the brain can interpret
What is an eye cup?
Vision in planaria that can detect light and dark but no image is formed
What is a compound eye?
Found in insects with a collection of thousands of individual eyes that detect many images
What is the cornea?
The part of the eye tissue that is transparent and lets light enter
What is the iris?
Muscular donut-shaped disk that gives eye color, surrounds pupil, and controls the amount of light that enters the eye
What is the retina?
Inner layer that has photoreceptors; photographic film
What is accommodation?
The focusing of objects at different distances. Light travels through the pupil and is focused by the lens. Images are transduced by the retina
The elastic lens is altered based on the distance the object is from the eye in what type of organism?
Mammals; as we age, the lens is less able to adjust (presbyopia)
What are rod cells?
Most dense around the retina’s edge and are extremely light-sensitive and produce colorless poorly defined images
What are cone cells?
Photoreceptors that are made for full-color vision in bright light and are concentrated in the central portion of the retina (the macula and fovea)
Each cone can detect how many hues?
100
Trichromats can see how many colors?
1,000,000 colors
Genes for cones come on the …
X chromosome
What is colorblindness?
Lacking one of the cone pigments usually in males. Inherit two red cones and a blue cone OR two green cones and a blue cone. Can see 10,000 colors with red-green being the most common colorblindness
What is tetrachromats?
These people have extra cones usually women that inherit and turn on two different red cones and green and blue that can see 100 million colors
What are cataracts?
Cloudy spots that form in the lens and can obscure vision and lead to blindness
What is glaucoma?
Results from too much pressure in the eye
How do we detect taste?
Taste receptors bind to small molecules and taste sensation depends on taste buds on the tongue and in the digestive tract. One taste bud is 50 modified epithelial cells. Some respond to dissolved chemicals while others provide support
How is taste classified?
Sweet, sour, salty, bitter, and UMAMI (savory)
A single taste bud can detect …
all 5 tastes (buds in different locations can be more sensitive to some tastes)
How do we detect smells?
Olfaction — more sensitive than taste. Human noses can distinguish between 1 trillion diff. odors. There are 100 to 1,000 distinct types of odor receptors, which lie in the olfactory epithelium of the nose and connect to the brain’s olfactory bulb
Somatic sensory systems report on information from 3 sources:
- external world
- positions of body parts
- interior of body
What are the 5 receptors?
Touch, position, temp., pain, and itch
What is the homunculus?
Image of how the brain sees the body relative to nerve density (fingertips have more nerves than the back)
