micro & macro anatomy of brain

Question 1

What do nerves do?

Answer 1

act as conductors, transmitting information from the skin and sense organs to the brain, which then sends signals to the muscles

Question 2

describe patellar reflex

Answer 2

simple neural circuit that involves a tap on the patellar tendon, which stretches the quadriceps muscle and activates sensory stretch receptor neurons
these neurons connect to motor neurons in the spinal cord, causing the quadriceps muscle to contract and the hamstrings to relax

Question 3

what are reflex arcs

Answer 3

• involve complex reflexes and neural control structures built upon simple reflexes
• sensory information enters the CNS at the back, and motor outputs are computed and sent out of the front, following a general pattern of organization seen in higher parts of the brain

Question 4

afferents vs efferents

Answer 4

aff: nerve cells which carry info toward higher processing centres

eff: nerve cells that carry signals toward motor output structures

Question 5

what are neurons?

Answer 5

• building blocks of the brain’s circuits, consisting of nerve cells
• function as signal processing devices with distinct components

Question 6

what are ‘typical’ neurons?

Answer 6

• characterized by their long axons, which function as output cables to transmit information
• use electrical signals to transmit information along their axons
• at the end of the axons, synapses are present, which utilize chemical signals to transmit the information to other neurons, muscle fibers, or glands
• many neurons have dendrites, which act as input cables, receiving chemical signals from multiple other neurons

Question 7

composition of neuron

Answer 7

Dendrites:
- main input receiving signals from multiple sources

Soma:
- contains the nucleus and synthesizes proteins

Axon:
- output cable, capable of projecting over long distances.
- each neuron has only one axon.

Question 8

describe communication between neurons

Answer 8

• involves the axon of one neuron making contact with the dendrites or somata of many other neurons
• occurs at specialized junctions called synapses
• synapti ccurrent froms multiple synpases are intergrated at axon hillock to determine the voltage
• the voltage determines the rate of nerve impulses, known as action potentials, that are sent down the axon to other neurons

Question 9

what are synapses

Answer 9

they act as chemical switches transmitting signals between neurons

Question 10

what are neural networks?

Answer 10

• neural networks both have convergent inputs (many synapse - many dendrite) and divergent outputs (many axon branches)
• synapses between neurons can exhibit plasticity, allowing for changes in connection strength
• plasticity enables the neural network to learn new associations between information represented by individual neurons

Question 11

what are astrocytes?

Answer 11

cells play a crucial role in the metabolic regulation of the nervous system, supporting neuronal function and maintaining the chemical balance of the brain

Question 12

what are Oligodendrocytes and Schwann cells

Answer 12

cells are responsible for producing the myelin sheath, a protective covering that surrounds and insulates axons in the nervous system. The myelin sheath helps to increase the speed and efficiency of signal transmission along the axons

Question 13

what are microglia

Answer 13

Microglia are immune cells in the nervous system. They are involved in immunological reactions and play a role in responding to and repairing damage in the nervous system.

Question 14

gray vs white matter

Answer 14

gray: many nerve bodies (neurons)
white: mostly nerve fibers (axon)

Question 15

what are decussations?

Answer 15

• crossing points of nerve tracts in the nervous system
• responsible for the organization of input and output pathways to and from the brain
• crossed, meaning that the left hemisphere of the brain primarily processes information from and controls the right side of the body, vice versa.
• allows for the coordination and integration of sensory and motor functions between the brain and the opposite sides of the body

Question 16

what is pineal gland

Answer 16

• small gland located deep within the brain
• regulate various physiological processes by secreting hormones
• # melatonin = reg sleep-wake cycle + circadian rhythms
• influenced by light and darkness

Question 17

what are commissures?

Answer 17

• fiber bundles that connect one brain hemisphere to the other
• numerous that facilitate communication and coordination between the hemispheres, enabling integration of functions and information processing across the brain

Question 18

corpus callosum

Answer 18

• most prominent commissure which connects the two hemispheres of the cerebral cortex
• allows for effective communication and information exchange between the two hemispheres

Question 19

meninges

Answer 19

three-layered protective covering of the central nervous system (CNS), consisting of the dura, arachnoid, and pia mater

Question 20

meningitis

Answer 20

an infection and inflammation of the meninges, often caused by a bacterial disease called meningococcus. The arachnoid layer reabsorbs cerebrospinal fluid (CSF), which is generated in the brain’s ventricles

Question 21

ventricles

Answer 21

• cavities in the brain filled with CSF
• CSF is secreted by the choroid plexus and circulates through the ventricles to the spinal cord then absorbed by arachnoid layer

Question 22

what does the blockage of CSF circulation lead to?

Answer 22

hydrocephalus - severe swelling of the ventricles

Question 23

blood-brain barrier

Answer 23

• formed by capillaries in the brain with no pores
• regulates the exchange of substances between the brain and blood through carrier proteins produced by astrocytes
• prevents rapid changes in the levels of substances in the brain and restricts the entry of many drugs and toxins, although fat-soluble substances can diffuse through

Question 24

cortex

Answer 24

• divided into two hemispheres and four lobes: frontal, parietal, occipital, and temporal
• sheet of nerve cells that covers the brain’s surface and is about 2mm thick, folded to fit within the skull

Question 25

thalamus

Answer 25

• important relay station between sensory input and the cortex.
• receives sensory information from all senses and relays it to the appropriate cortical areas
• receives feedback from the cortex, possibly conveying signals of expectation or attention
• involved in sleep, attention, and sensory processing.

Question 26

hypothalamus

Answer 26

• regulates various bodily functions, including appetite, thirst, blood pressure, body temperature, sleep-wake rhythms, and hormone secretion
• controls the pituitary gland, which is the most important hormone-secreting gland in the body

Question 27

basal ganglia

Answer 27

• clusters of neurons involved in action selection, habits, and addiction
• form feedback circuits with the cortex, passing through the basal ganglia to the thalamus and back to the cortex
• components of the basal ganglia include the caudate, putamen, globus pallidus, subthalamic nucleus, and substantia nigra

Question 28

cerebellum

Answer 28

• responsible for motor control and coordination
• receives sensory input from various parts of the brain and learns to associate it with motor output patterns, making movements smooth and automatic
• damage to the cerebellum can result in ataxia, apraxia, or balance disturbances

Question 29

limbic system

Answer 29

• group of structures located around the edge of the cortex
• includes the amygdala, hypothalamus, thalamus, hippocampus, and cingulate cortex
• involved in emotional responses such as fear, anger, pleasure, and arousal