北师大版七年级生物下册知识点

北师大版七年级生物下册知识点.

消化管包括口腔、食管、胃、小肠和大肠，消化腺包括唾液腺、胃腺、肝脏和胰腺。

二、消化的过程：机械消化和化学消化。机械消化指食物在消化道中被切碎、搅拌和挤压，以便于化学消化。化学消化指消化液中的酶分解食物中的营养成分。

三、食物中的营养物质的吸收：主要发生在小肠中，通过小肠壁上的细胞吸收并进入血液循环系统，再被运输到身体各处供能或储存。

四、消化和吸收的相关器官和酶：

1.口腔：齿和舌帮助机械消化，唾液中的淀粉酶开始化学消化。

2.胃：胃液中的胃蛋白酶和胃脂肪酶开始消化蛋白质和脂肪。

3.小肠：小肠液中的肠蛋白酶、肠脂肪酶和肠淀粉酶分别消化蛋白质、脂肪和碳水化合物。

4.肝脏和胰腺：分别分泌胆汁和胰液，帮助消化和吸收。

五、消化和吸收的调节：神经和荷尔蒙的调节，以保持消化系统的正常功能。

The digestive system consists of the XXX main n is to digest food and absorb nutrients.

XXX。XXX chew and grind food。while the tongue mixes it with saliva.

The pharynx is the passage of food and has no digestive n.

The esophagus is the passage of food and has no digestive n.

XXX.

The small intestine is the main site of n and n (the beginning of the small intestine is the duodenum).

The large intestine pushes food residue towards the anus (the beginning of the large intestine is the cecum).

The anus is the exit for waste.

XXX。and salivary amylase can digest starch (starch → maltose)。The liver secretes bile。which does not contain digestive enzymes。but can XXX.

The pancreas。a digestive gland。XXX digesting sugars。XXX.

XXX。which XXX.

XXX XXX digesting sugars。XXX.

Food n is the process of hydrolyzing the XXX。protein and fat need to be digested before n。and their XXX。XXX。the substances that can be absorbed include glucose。glycerol。XXX it XXX。XXX.

The n process of starch。protein and fat is as follows:

Salivary amylase (multiple enzymes)

Starch → XXX → glucose

XXX and small intestine

Protease (multiple enzymes)

Protein → partially digested → amino acids

Stomach and small intestine

Bile (multiple enzymes)

Fat → fat particles → glycerol + fatty acids

Small intestine

n refers to the process of water。anic salts。vitamins and small molecules formed after food n。such as glucose。amino

acids。glycerol。and fatty acids。entering the blood through the XXX。pharynx and esophagus have no nutrient n n。the stomach can absorb some water and alcohol。and the large intestine can absorb a small amount of water。XXX。XXX.

The small intestine is the main site for digesting food and absorbing nutrients because it is the longest segment of the digestive tract。about 6 meters long。The surface of the small intestine has circular folds。XXX。greatly increasing the surface area for n.

毛细胞可以增加小肠的吸收面积，而小肠绒毛内部有丰富的毛细血管和淋巴管，这有助于促进小肠的吸收功能。此外，小肠绒毛的壁非常薄，由单层上皮细胞构成，使得营养物质更容易通过。因此，小肠是消化和吸收的主要部位。

均衡膳食的基本要求包括：食物多样化，以谷类为主；多食用蔬菜、水果和薯类；常吃奶类、豆类或其制品；适量食用鱼、禽、蛋、瘦肉，少食用肥肉和荤油；膳食要清淡少盐；限制饮酒；保持适宜的体重，控制食量与体力活动的平衡；食物要清洁卫生、不变质。营养合理的饮食应该每日均衡地摄入五