The human brain Flashcards
Development of the brain
The anterior part of the neural tube expands to form the brain.
During the development of vertebrate embryos, a neural tube forms along the whole of the dorsal side.
Most of the neural tube becomes the spinal cord and the anterior end expands and develops into the brain as part of a process called cephalization, the development of a head.
Role of the medulla oblongata
The medulla oblongata is used in autonomic control of gut muscles, breathing, blood vessels and heart muscle.
Role of the cerebellum
The cerebellum coordinated uncosncious functions, such as posture, non-voluntary movement and balance.
Role of the hypothalamus
The hypothalamus is the interface between the brain and the pituitary gland, synthesizing the hormones secreted by the posterior pituitary, and releasing factors that regulate the secretion of hormones by the anterior pituitary.
Role of the pituitary gland
The pituitary gland: the posterior lobe stores and releases hormones produced by the hypothalamus and the anterior lobe produces and secretes hormones that regulate many body functions.
Role of the cerebral hemispheres
The cerebral hemispheres act as the intergrating center for high complex functions such as learning, memory and emotions.
Lesion studies
Lesion studies gave the first useful information about brain functions.
EX 1: French neurologist Charcot performed an automosy on a man who could only say the word “Tan” - He found a single large tumor damaging the lower left side of the brain. From this he deduced that this part of the brain is invovled with speech.
EX 2: Phineas Gage suffered severe damage to the frontal lobes of his brian when an accidental caused a large metal rod to pass through his forehead. Even though he recovered, his personality and capacity of social interactions were altered.
MRI
Magnetic resonance imaging - to investigate the internal structure of the body (looking for tumors, other abnormalities)
fMRI = Functional magentic resonance imaging - allows parts of the brain that are activated by specific thought processes to be identified. Active parts of the brain receive increased blood flow, made visible by the injection of harmless dies.
Visual Cortex
Each of the two cerebral hemispheres has a visual cortex in which neural signals originating from light sensitive rod and cone cells in the retina are processed.
Broca’s area
Part of the left cerebral hemisphere that controls the production of speech.
Nucleus accumbens
There is a nucleus accumbens in each of the cerebral hemisoheres. It is the pleasure or reward center of the brain. A variety of stimuli (food, sex, etc.) cause the release of the neurotransmitter dopamine in the nucleus accumbens, which cause feelings of well-being, pleasure, and satisfaction.
Coke, heroine, nicotine = adictive b/c of artificial release of dopamine in the nucleus accumbens.
Autonomic nervous system
The autonomic nervous system controls involuntary processes in the body using centers located in the medulla oblangata.
Parasympathetic nerves cause an increase in blood flow to the gut wall during digestion and absorption of food.
Sympathetic nerves cause a decrease in blood flow during fasting or when blood is needed elsewhere.
The cerebral cortex
The cerebral cortex forms a larger proportion of the brain and is more highly developed in humans than other animals.
Evolution of the cerebral cortex
The human cerebral cortex has become enlarged principally by an increase in total area with etensive folding to accomodate it within the cranium.
Functions of the cerebral hemispheres
The cerebral hemispheres are responsible for higher order functions such as learning, memory, speech and emotions.
