● The `color{violet}("alimentary canal")` begins with an anterior opening – the `color{brown}("mouth,")` and it opens out posteriorly through the `color{brown}("anus.")`
`star` `color{green}("Buccal cavity:")`
● The `color{violet}("mouth leads")` to the `color{violet}("buccal cavity")` or `color{violet}("oral cavity")`.
● The `color{violet}("oral cavity")` has a number of `color{brown}("teeth")` and a `color{brown}("muscular tongue.")`
● Each `color{violet}("tooth")` is embedded in a `color{violet}("socket of jaw bone.")`
● This type of attachment is called `color{brown}("thecodont.")`
● Majority of `color{violet}("mammals")` including human being forms two sets of `color{violet}("teeth")` during their life, a set of temporary milk or `color{violet}("deciduous teeth")` replaced by a set of permanent or `color{violet}("adult teeth.")`
● This type of dentition is called `color{brown}("diphyodont.")`
● An adult human has `color{violet}("32 permanent teeth")` which are of four different types (`color{violet}("Heterodont dentition")` ), namely, incisors (`color{violet}(I)`), canine (`color{violet}(C)`), premolars (`color{violet}("PM")`) and molars (`color{violet}("M")`).
● Arrangement of teeth in each half of the upper and lower jaw in the order `color{brown}("I, C, PM, M")` is represented by a `color{violet}("dental formula")` which in human is
2123
2123
● The `color{violet}("hard chewing")` surface of the `color{violet}("teeth")`, made up of `color{brown}("enamel,")` helps in the `color{violet}("mastication of food.")`
● The `color{brown}("tongue")` is a freely `color{violet}("movable muscular organ")` attached to the floor of the `color{violet}("oral cavity")` by the frenulum.
● The upper surface of the tongue has `color{violet}("small projections")` called `color{brown}("papillae,")` some of which bear taste buds.
`star` `color{green}("Pharynx:")`
● The `color{violet}("oral cavity")` leads into a short `color{brown}("pharynx")` which serves as a common passage for `color{violet}("food and air")`.
● The `color{brown}("oesophagus")` and the `color{brown}("trachea")` (wind pipe) open into the pharynx.
● A cartilaginous flap called `color{brown}("epiglottis")` prevents the entry of `color{violet}("food")` into the `color{brown}("glottis")` – opening of the wind pipe – during swallowing.
`star` `color{green}("Oesophagus:")`
● The `color{violet}("oesophagus")` is a thin, long tube which `color{violet}("extends posteriorly")` passing through the neck, thorax and diaphragm and leads to a `color{violet}("‘J’")` shaped bag like structure called `color{brown}("stomach.")`
● A muscular sphincter (`color{brown}("gastro-oesophageal")`) regulates the opening of `color{violet}("oesophagus")` into the `color{violet}("stomach.")`
`star` `color{green}("Stomach:")`
● The `color{violet}("stomach")`, located in the `color{violet}("upper left portion")` of the `color{violet}("abdominal cavity")`, has three major parts – a cardiac portion into which the `color{violet}("oesophagus")` opens, a `color{brown}("fundic")` region and a pyloric portion which opens into the first part of `color{violet}("small intestine.")`
`star` `color{green}("Small Intestine:")`
● `color{violet}("Small intestine")` is distinguishable into three regions, a `color{violet}("‘U’")` shaped `color{brown}("duodenum,")` a long coiled middle portion `color{brown}("jejunum")` and a highly coiled `color{brown}("ileum.")`
● The opening of the `color{violet}("stomach")` into the `color{violet}("duodenum")` is guarded by the `color{brown}("pyloric sphincter.")`
`star` `color{green}("Large Intestine:")`
● `color{brown}("Ileum")` opens into the `color{violet}("large intestine.")`
● It consists of `color{violet}("caecum, colon")` and `color{violet}("rectum.")`
● `color{brown}("Caecum")` is a small blind sac which hosts some `color{violet}("symbiotic micro-organisms")`.
● A narrow finger-like tubular projection, the `color{brown}("vermiform appendix")` which is a `color{violet}("vestigial organ")`, arises from the `color{violet}("caecum.")`
● The `color{violet}("caecum")` opens into the `color{violet}("colon.")`
● The `color{brown}("colon")` is divided into three parts – an `color{violet}("ascending, a transverse")` and a `color{violet}("descending")` part.
● The `color{violet}("descending part")` opens into the `color{brown}("rectum")` which opens out through the anus.
● The `color{violet}("alimentary canal")` begins with an anterior opening – the `color{brown}("mouth,")` and it opens out posteriorly through the `color{brown}("anus.")`
`star` `color{green}("Buccal cavity:")`
● The `color{violet}("mouth leads")` to the `color{violet}("buccal cavity")` or `color{violet}("oral cavity")`.
● The `color{violet}("oral cavity")` has a number of `color{brown}("teeth")` and a `color{brown}("muscular tongue.")`
● Each `color{violet}("tooth")` is embedded in a `color{violet}("socket of jaw bone.")`
● This type of attachment is called `color{brown}("thecodont.")`
● Majority of `color{violet}("mammals")` including human being forms two sets of `color{violet}("teeth")` during their life, a set of temporary milk or `color{violet}("deciduous teeth")` replaced by a set of permanent or `color{violet}("adult teeth.")`
● This type of dentition is called `color{brown}("diphyodont.")`
● An adult human has `color{violet}("32 permanent teeth")` which are of four different types (`color{violet}("Heterodont dentition")` ), namely, incisors (`color{violet}(I)`), canine (`color{violet}(C)`), premolars (`color{violet}("PM")`) and molars (`color{violet}("M")`).
● Arrangement of teeth in each half of the upper and lower jaw in the order `color{brown}("I, C, PM, M")` is represented by a `color{violet}("dental formula")` which in human is
2123
2123
● The `color{violet}("hard chewing")` surface of the `color{violet}("teeth")`, made up of `color{brown}("enamel,")` helps in the `color{violet}("mastication of food.")`
● The `color{brown}("tongue")` is a freely `color{violet}("movable muscular organ")` attached to the floor of the `color{violet}("oral cavity")` by the frenulum.
● The upper surface of the tongue has `color{violet}("small projections")` called `color{brown}("papillae,")` some of which bear taste buds.
`star` `color{green}("Pharynx:")`
● The `color{violet}("oral cavity")` leads into a short `color{brown}("pharynx")` which serves as a common passage for `color{violet}("food and air")`.
● The `color{brown}("oesophagus")` and the `color{brown}("trachea")` (wind pipe) open into the pharynx.
● A cartilaginous flap called `color{brown}("epiglottis")` prevents the entry of `color{violet}("food")` into the `color{brown}("glottis")` – opening of the wind pipe – during swallowing.
`star` `color{green}("Oesophagus:")`
● The `color{violet}("oesophagus")` is a thin, long tube which `color{violet}("extends posteriorly")` passing through the neck, thorax and diaphragm and leads to a `color{violet}("‘J’")` shaped bag like structure called `color{brown}("stomach.")`
● A muscular sphincter (`color{brown}("gastro-oesophageal")`) regulates the opening of `color{violet}("oesophagus")` into the `color{violet}("stomach.")`
`star` `color{green}("Stomach:")`
● The `color{violet}("stomach")`, located in the `color{violet}("upper left portion")` of the `color{violet}("abdominal cavity")`, has three major parts – a cardiac portion into which the `color{violet}("oesophagus")` opens, a `color{brown}("fundic")` region and a pyloric portion which opens into the first part of `color{violet}("small intestine.")`
`star` `color{green}("Small Intestine:")`
● `color{violet}("Small intestine")` is distinguishable into three regions, a `color{violet}("‘U’")` shaped `color{brown}("duodenum,")` a long coiled middle portion `color{brown}("jejunum")` and a highly coiled `color{brown}("ileum.")`
● The opening of the `color{violet}("stomach")` into the `color{violet}("duodenum")` is guarded by the `color{brown}("pyloric sphincter.")`
`star` `color{green}("Large Intestine:")`
● `color{brown}("Ileum")` opens into the `color{violet}("large intestine.")`
● It consists of `color{violet}("caecum, colon")` and `color{violet}("rectum.")`
● `color{brown}("Caecum")` is a small blind sac which hosts some `color{violet}("symbiotic micro-organisms")`.
● A narrow finger-like tubular projection, the `color{brown}("vermiform appendix")` which is a `color{violet}("vestigial organ")`, arises from the `color{violet}("caecum.")`
● The `color{violet}("caecum")` opens into the `color{violet}("colon.")`
● The `color{brown}("colon")` is divided into three parts – an `color{violet}("ascending, a transverse")` and a `color{violet}("descending")` part.
● The `color{violet}("descending part")` opens into the `color{brown}("rectum")` which opens out through the anus.