Human Body Systems: Nutrient Absorption and Reproduction

The levels of organization in the human body:

Connective and Epithelial Tissue Connective Functions – Provides support for the body and connects its parts  Example: blood, bone, cartilage, fat Epithelial Functions – Covers interior and exterior body surfaces; protects, absorbs, filters, and secretes  Example: skin, blood vessels

Muscle and Nervous Tissue Muscle – provides movement with help from the skeleton (contracts)  Example: heart, biceps, stomach Nervous – Transmits and processes information in the body  Example: brain, sciatic nerve

Tissues  Organ  Organ Systems Human body has 11 organ systems: – Nervous – Integumentary – Respiratory – Circulatory – Digestive – Excretory – Skeletal – Muscular – Endocrine – Reproductive – Lymphatic – Immune

Homeostasis All 11 body systems interact to maintain homeostasis. – The Nervous system coordinates the body functions to maintain homeostasis. Feedback inhibition/Negative feedback: a stimulus produces a response that opposes the original stimulus. – Ex: body temperature and home heating unit

Fun Facts about… the Digestive System We eat about 500kg of food per year. 1.7 liters of saliva is produced each day. The stomach must create a new lining of mucous every 2 weeks, otherwise it would digest itself. An adult stomach can hold 1.5 liters of food. In an average person, it takes 8 seconds for food to move through the esophagus, 1-3 hours in the stomach, 3-5 hours in the small intestine, and 3-4 days in the large intestine.

Why is it important? The digestive system’s function is to help convert food into simpler molecules that can be absorbed and used by the cells of the body.

Step 1. The Mouth Teeth – Chewing begins the process of mechanical digestion Saliva – Begins the process of chemical digestion The enzyme AMYLASE breaks down carbohydrates

Step 2. The Esophagus Food tube that connects the mouth to the stomach The bolus moves through the esophagus by PERISTALIS – Muscles in the walls of the esophagus contract in waves, which pushes the bolus until it reaches the stomach

“Help Me”! My food went down the wrong pipe!

Step 3. The Stomach Chemical Digestion: – The stomach contains hydrochloric acid – This acid activates an enzyme, PEPSIN Pepsin is responsible for breaking down protein – Chemical digestion of carbohydrates stops while in the stomach

The Stomach Mechanical Digestion: – Stomach muscles contract to churn and mix the stomach acid and food to create CHYME – After about an hour of churning, the chyme begins to flow into the small intestine

Step 4. The Small Intestine Most of chemical digestion and absorption of food you eat occurs in the small intestine. As chyme enters the S.I., it mixes with enzymes and digestive juices from the pancreas and liver.

How does the Small Intestine Work? In the lining of the small intestine, there are folds that are covered in fingerlike projections called VILLI and microvilli Carbohydrates and protein products are absorbed into the capillaries in the villi. After the small intestine, the only things remaining are water, cellulose, and other indigestible substances

Step 5. The Large Intestine The large intestine’s main role is to remove water from the undigested material that is left. The concentrated waste material that remains after the water has been removed passes through the rectum and is eliminated from the body.

Accessory Structures: The Pancreas Functions: – Produces hormones that regulate blood sugar – Produces enzymes that break down carbohydrates, proteins, lipids, and nucleic acids – Neutralizes stomach acid that allows the enzymes to be effective

Accessory Structures: The Liver Organ located just above and to the right of the stomach Function: – Produces BILE Helps dissolved droplets of fat found in the small intestine Extra bile is stored in the gall bladder

Digestive System

Connection? How does the digestive system work with other systems? Circulatory: the digestive system breaks down food and the circulatory system will transport the nutrients to the cells. Excretory: circulatory system picks up waste in the blood and takes it to the excretory system to help waste exit the body. Muscular: muscles in the esophagus, stomach and intestines help to move food through the body Nervous: the brain (hypothalamus) triggers the body’s sense of hunger

Reproduction and Endocrine

Fun Facts about… the Endocrine System It contains 30 hormones that are responsible for regulating different body processes. Your mood is largely influenced by the Endocrine System. A guy’s voice change is brought on by your endocrine system. Your height is influenced by inherited genes and hormones.

Male Reproductive System Main function: – Testes: Produce sperm

Female Reproductive System Main functions – Ovaries: Produce unfertilized eggs – Prepare the female’s body to nourish a developing embryo

Connection? How does the reproductive system work with other systems? Endocrine: the endocrine system make hormones that maintain homeostasis and allow the body to go through puberty and to make sex cells – Makes testosterone and estrogen Nervous: interprets feedback from other systems and sends signals to the endocrine system to release hormones when needed Circulatory: the circulatory system transports the hormones throughout the body