Biology PARTS OF A BRAIN

KEY TOPICS

`star` Forebrain
`star` Midbrain
`star` Hindbrain

FOREBRAIN

● The `color{violet}("forebrain")` consists of `color{brown}("cerebrum, thalamus")` and `color{brown}("hypothalamus.")`

● `color{violet}("Cerebrum")` forms the major part of the `color{violet}("human brain.")`

● A deep cleft divides the `color{violet}("cerebrum longitudinally")` into two halves, which are termed as the left and right `color{brown}("cerebral hemispheres.")`

● The `color{violet}("hemispheres")` are connected by a tract of `color{violet}("nerve fibres")` called `color{brown}("corpus callosum.")`

● The layer of cells which covers the `color{violet}("cerebral hemisphere")` is called `color{brown}("cerebral cortex")` and is thrown into `color{violet}("prominent folds.")`

● The `color{violet}("cerebral cortex")` is referred to as the `color{brown}("grey matter")` due to its `color{violet}("greyish appearance.")`

● The `color{violet}("neuron cell bodies")` are concentrated here giving the colour.

● The `color{violet}("cerebral cortex")` contains `color{brown}("motor areas, sensory areas")` and large regions that are neither clearly sensory nor `color{violet}("motor in function.")`

● These regions called as the `color{brown}("association areas")` are responsible for complex functions like `color{violet}("intersensory associations, memory")` and `color{violet}("communication.")`

● `color{violet}("Fibres")` of the tracts are covered with the `color{violet}("myelin sheath,")` which constitute the inner part of `color{violet}("cerebral hemisphere.")`

● They give an `color{violet}("opaque white")` appearance to the layer and, hence, is called the `color{brown}("white matter.")`

● The `color{violet}("cerebrum wraps")` around a structure called `color{brown}("thalamus,")` which is a major coordinating centre for `color{violet}("sensory")` and `color{violet}("motor signaling.")`

● Another very important part of the brain called `color{brown}("hypothalamus")` lies at the base of the `color{violet}("thalamus.")`

● The `color{brown}("hypothalamus")` contains a number of centres which `color{violet}("control body temperature")` , urge for eating and drinking.

● It also contains several groups of `color{violet}("neurosecretory cells")`, which secrete hormones called `color{brown}("hypothalamic hormones.")`

● The inner parts of `color{violet}("cerebral hemispheres")` and a group of associated deep structures like `color{brown}("amygdala, hippocampus,")` etc., form a complex structure called the `color{violet}("limbic lobe")` or `color{violet}("limbic system.")`

● Along with the `color{violet}("hypothalamus,")` it is involved in the `color{violet}("regulation of sexual")` behaviour, expression of `color{violet}("emotional reactions")` (e.g., excitement, pleasure, rage and fear), and `color{violet}("motivation.")`

MIDBRAIN

● The `color{brown}("midbrain")` is located between the `color{brown}("thalamus/hypothalamus")` of the `color{violet}("forebrain and pons")` of the `color{violet}("hindbrain.")`

● A canal called the `color{brown}("cerebral aqueduct")` passess through the `color{violet}("midbrain.")`

● The `color{violet}("dorsal portion")` of the `color{violet}("midbrain")` consists mainly of four round swellings (lobes) called `color{brown}("corpora quadrigemina.")`

● `color{violet}("Midbrain and hindbrain")` form the `color{brown}("brain stem.")`

HINDBRAIN

● The `color{violet}("hindbrain")` comprises `color{brown}("pons, cerebellum")` and `color{brown}("medulla")` (also called the `color{brown}("medulla oblongata).")`

● `color{violet}("Pons")` consists of `color{brown}("fibre")` tracts that interconnect different regions of `color{violet}("the brain.")`

● `color{violet}("Cerebellum")` has very convoluted surface in order to provide the additional space for many more `color{violet}("neurons.")`

● The `color{violet}("medulla")` of the `color{violet}("brain")` is connected to the `color{violet}("spinal cord.")`

● The `color{violet}("medulla")` contains centres which control `color{brown}("respiration, cardiovascular reflexes")` and `color{brown}("gastric secretions.")`

 
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