The Digestive and Endocrine Systems

Following the Digestion of a Meal  Functions of the Digestive System Main function is to disassemble the food you eat into its component molecules s that it can be used as energy (ATP) by your body.

 Functions of the Digestive System

Main function is to disassemble the food you eat into its component molecules s that it can be used as energy (ATP) by your body.

All of these organs work together to break down food into simpler compounds that can be absorbed by the body.

Steps of Digestion 1. System takes ingested food & begins moving it through the digestive tract. As food moves it breaks down mechanically and chemically 2. The system absorbs the digested food & distributes it to your cells 3. It eliminates undigested materials from the body

Steps of Digestion

1. System takes ingested food & begins moving it through the digestive tract. As food moves it breaks down mechanically and chemically

2. The system absorbs the digested food & distributes it to your cells

3. It eliminates undigested materials from the body

 The Mouth - The disassembly line STARTS at the mouth What happens when you chew? Your tongue moves food around & helps position it b/t your teeth Chewing is a form mechanical digestion = the physical process of breaking down food into smaller pieces. This prepares food for chemical digestion Chemical digestion = the process of changing food on a molecular level through the action of enzymes

- The disassembly line STARTS at the mouth

What happens when you chew?

Your tongue moves food around & helps position it b/t your teeth

Chewing is a form mechanical digestion = the physical process of breaking down food into smaller pieces. This prepares food for chemical digestion

Chemical digestion = the process of changing food on a molecular level through the action of enzymes

Chemical Digestion begins in Mouth Saliva in mouth contains digestive enzymes, called amylase , which breaks down starch into smaller molecules In the stomach, amylase continues to digest food for about 30 min.

Chemical Digestion begins in Mouth

Saliva in mouth contains digestive enzymes, called amylase , which breaks down starch into smaller molecules

In the stomach, amylase continues to digest food for about 30 min.

Starch

Swallowing Your Food Chewed food becomes a ball and is swallowed Swallowing forces food into throat and then to the esophagus = a muscular tube that connects the mouth to the stomach Food moves through the esophagus by peristalsis = a series of involuntary smooth muscle contraction along the walls of the digestive tract

Swallowing Your Food

Chewed food becomes a ball and is swallowed

Swallowing forces food into throat and then to the esophagus = a muscular tube that connects the mouth to the stomach

Food moves through the esophagus by peristalsis = a series of involuntary smooth muscle contraction along the walls of the digestive tract

Peristalsis

The epiglottis = a flap of cartilage that closes over the opening to the respiratory tract as you swallow, keeping food out After food passes, epiglottis opens again If you talk or laugh as you swallow, food may enter the upper portion of the respiratory tract Your response is to choke & cough, forcing food out of the respiratory tract

The epiglottis = a flap of cartilage that closes over the opening to the respiratory tract as you swallow, keeping food out

After food passes, epiglottis opens again

If you talk or laugh as you swallow, food may enter the upper portion of the respiratory tract

Your response is to choke & cough, forcing food out of the respiratory tract

 The Stomach Stomach = a muscular pouchlike enlargement of the digestive tract Muscle Churning The walls of the stomach are composed of 3 layers of involuntary muscles When the muscles contract, they work to physically breakdown food, creating smaller pieces The pieces mix with digestive juices produced by the stomach

Stomach = a muscular pouchlike enlargement of the digestive tract

Muscle Churning

The walls of the stomach are composed of 3 layers of involuntary muscles

When the muscles contract, they work to physically breakdown food, creating smaller pieces

The pieces mix with digestive juices produced by the stomach

Chemical Digestion in the stomach The lining of the stomach contains millions of glands that secrete a mixture of chemicals called gastric juice Gastric juice contains pepsin & hydrochloric aced Pepsin = an enzyme that begins the chemical digestion of proteins in food

Chemical Digestion in the stomach

The lining of the stomach contains millions of glands that secrete a mixture of chemicals called gastric juice

Gastric juice contains pepsin & hydrochloric aced

Pepsin = an enzyme that begins the chemical digestion of proteins in food

The lining of the stomach secretes mucus that forms a protective layer b/t it and the acidic environment of the stomach Food remains in stomach for about 2-4 hrs When food leaves it is the consistency of tomato soup (YUMMY!)

The lining of the stomach secretes mucus that forms a protective layer b/t it and the acidic environment of the stomach

Food remains in stomach for about 2-4 hrs

When food leaves it is the consistency of tomato soup (YUMMY!)

 The Small Intestine - Small intestine = a muscular tube about 6 m long Called “small” because of how narrow it is (only 2.5 cm in diameter) - Digestion is COMPLETED here - First 25 cm of the small intestine called the duodenum

- Small intestine = a muscular tube about 6 m long

Called “small” because of how narrow it is (only 2.5 cm in diameter)

- Digestion is COMPLETED here

- First 25 cm of the small intestine called the duodenum

Secretions of the Pancreas Pancreas = soft, flattened gland that secretes both digestive enzymes & hormones The mixture of enzymes it releases break down carbs, proteins, & fats

Secretions of the Pancreas

Pancreas = soft, flattened gland that secretes both digestive enzymes & hormones

The mixture of enzymes it releases break down carbs, proteins, & fats

Secretions of the Liver Liver = large, complex organ that produces bile Bile = chemical substance that helps break down fats Made by the liver, but stored in the gallbladder From the gallbladder, bile passes into duodenum Bile causes further digestion by breaking large drops of fat into smaller droplets Gallstones form when bile in the gallbladder becomes too concentrated due to high levels of cholesterol in you diet

Secretions of the Liver

Liver = large, complex organ that produces bile

Bile = chemical substance that helps break down fats

Made by the liver, but stored in the gallbladder

From the gallbladder, bile passes into duodenum

Bile causes further digestion by breaking large drops of fat into smaller droplets

Gallstones form when bile in the gallbladder becomes too concentrated due to high levels of cholesterol in you diet

LIVER

Absorption of Food Liquid food stays in the intestine for 3-5 hrs. as it is moved through As food moves it passes over thousands of tiny fingerlike structures called villus = a single projection on the lining of small intestine that function in the absorption of food Now that food is in the form of small molecules, it can be absorbed directly into the cells of the villi (plural for villus) Food then diffuses into blood vessels of the villus & enter the bloodstream * Villi are the link between the digestive system & the circulatory system

Absorption of Food

Liquid food stays in the intestine for 3-5 hrs. as it is moved through

As food moves it passes over thousands of tiny fingerlike structures called villus = a single projection on the lining of small intestine that function in the absorption of food

Now that food is in the form of small molecules, it can be absorbed directly into the cells of the villi (plural for villus)

Food then diffuses into blood vessels of the villus & enter the bloodstream

* Villi are the link between the digestive system & the circulatory system

 The Large Intestine - All indigestible material from a meal then moves into the large intestine = a muscular tube that is also called the colon - Large intestine is only about 1.5 m long, but it is much wider that the small intestine ( about 6.5cm in diameter)

- All indigestible material from a meal then moves into the large intestine = a muscular tube that is also called the colon

- Large intestine is only about 1.5 m long, but it is much wider that the small intestine ( about 6.5cm in diameter)

Water Absorption As indigestible mixture passes through the large intestine, water and salts are absorbed by the intestinal walls, leaving behind a more solid material This way water in NOT wasted

Water Absorption

As indigestible mixture passes through the large intestine, water and salts are absorbed by the intestinal walls, leaving behind a more solid material

This way water in NOT wasted

Bacteria in the large intestine make some B vitamins and Vitamin K, which are absorbed as needed by the body These bacteria also stop harmful bacteria from colonizing, reducing the risk of intestinal infections

Bacteria in the large intestine make some B vitamins and Vitamin K, which are absorbed as needed by the body

These bacteria also stop harmful bacteria from colonizing, reducing the risk of intestinal infections

Elimination of Wastes After 18-24 hrs in the large intestine, the remaining indigestible material, now called feces, reaches the rectum Rectum = the last part of the digestive system

Elimination of Wastes

After 18-24 hrs in the large intestine, the remaining indigestible material, now called feces, reaches the rectum

Rectum = the last part of the digestive system

YOUR ENTIRE MEAL’S JOURNEY THOUGH THE DIGESTIVE TRACT HAS TAKEN BETWEEN 24-33 HOURS !

mouth esophagus stomach liver gall bladder pancreas small intestine large intestine appendix rectum anus colon

Ch. 35.2: Nutrition  The Vital Nutrients - Six basic kinds of nutrients can be found: 1. Carbohydrates Main source of energy 2. Fats Used to store energy 3. Proteins Form part of muscles and many cell structures, including the cell membrane

Ch. 35.2: Nutrition

 The Vital Nutrients

- Six basic kinds of nutrients can be found:

1. Carbohydrates

Main source of energy

2. Fats

Used to store energy

3. Proteins

Form part of muscles and many cell structures, including the cell membrane

4. Minerals Serve as structural materials 5. Vitamins Needed for growth and metabolism 6. Water Facilitates chemical reactions, helps dissolve materials and helps maintain the body’s temperature Ca B 12 Cr Mg Vitamin C Vitamin D

4. Minerals

Serve as structural materials

5. Vitamins

Needed for growth and metabolism

6. Water

Facilitates chemical reactions, helps dissolve materials and helps maintain the body’s temperature

USDA Food Guide Pyramid

The Endocrine System Control of the Body Internal control of the body is directed by 2 systems: The Nervous System The Endocrine System

Control of the Body

Internal control of the body is directed by 2 systems:

The Nervous System

The Endocrine System

The Endocrine System is made up of a series of glands called endocrine glands These glands release chemicals directly into the bloodstream The chemicals act as messengers, relaying information to other parts of the body

The Endocrine System is made up of a series of glands called endocrine glands

These glands release chemicals directly into the bloodstream

The chemicals act as messengers, relaying information to other parts of the body

Interaction of the Nervous & Endocrine Systems The endocrine system and the nervous system work together to maintain homeostasis within the body Hypothalamus = the portion of the brain that receives messages from other areas of the brain & internal organs When a change in homeostasis is detected, the hypothalamus stimulates the pituitary gland

Interaction of the Nervous & Endocrine Systems

The endocrine system and the nervous system work together to maintain homeostasis within the body

Hypothalamus = the portion of the brain that receives messages from other areas of the brain & internal organs

When a change in homeostasis is detected, the hypothalamus stimulates the pituitary gland

pituitary gland = the main gland of the endocrine system and is located in the skull just beneath the hypothalamus The pituitary gland releases its own chemicals or stimulates other glands to release theirs

pituitary gland = the main gland of the endocrine system and is located in the skull just beneath the hypothalamus

The pituitary gland releases its own chemicals or stimulates other glands to release theirs

Endocrine Control of the Body Hormones = the chemicals secreted by endocrine glands Hormones are chemicals released in one part of an organism that affects another part of the organism They convey information to other cells in your body, giving them instructions regarding your metabolism, growth, development, and behavior

Endocrine Control of the Body

Hormones = the chemicals secreted by endocrine glands

Hormones are chemicals released in one part of an organism that affects another part of the organism

They convey information to other cells in your body, giving them instructions regarding your metabolism, growth, development, and behavior

Hormones travel in the bloodstream and attach to specific binding sites of target cells These binding sites are called receptors

Hormones travel in the bloodstream and attach to specific binding sites of target cells

These binding sites are called receptors

Lock and Key Analogy Hormone = key Receptor = lock Like a key with a lock, hormones only fit certain receptors. Even a close fit won’t turn the lock.

Example of Endocrine Control (hGH) Human growth hormone (hGH) is a good example of an endocrine system hormone When your body is growing, blood glucose levels are slightly lowered as the growing cells use up the sugar in your cells The low blood glucose level is detected by the hypothalamus, which stimulates the production & release of hGH from the pituitary gland into the bloodstream

Example of Endocrine Control (hGH)

Human growth hormone (hGH) is a good example of an endocrine system hormone

When your body is growing, blood glucose levels are slightly lowered as the growing cells use up the sugar in your cells

The low blood glucose level is detected by the hypothalamus, which stimulates the production & release of hGH from the pituitary gland into the bloodstream

hGH binds to receptors on liver cells, stimulating liver cells to release glucose into the blood Your cells need this glucose in order to continue growing LOW GLUCOSE detected by hypothalamus (endocrine system) Pituitary gland releases hGH hGH stimulates liver to release extra glucose Homeostasis restored  glucose level is NORMAL

hGH binds to receptors on liver cells, stimulating liver cells to release glucose into the blood

Your cells need this glucose in order to continue growing

1. Hypothalamus tells pituitary to release hGH 2. hGH signals liver to release stored glucose 3. Higher glucose level signals hypothalamus that homeostasis is restored

Negative Feedback Control When homeostasis is disrupted the regulation of the endocrine system is controlled most often through one type of internal feedback mechanism called a negative feedback system In this system the hormones, or their effects, are fed back to inhibit the original signal (normal signal) Once homeostasis is reached, the signal is stopped & the hormone is no longer released

Negative Feedback Control

When homeostasis is disrupted the regulation of the endocrine system is controlled most often through one type of internal feedback mechanism called a negative feedback system

In this system the hormones, or their effects, are fed back to inhibit the original signal (normal signal)

Once homeostasis is reached, the signal is stopped & the hormone is no longer released

Feedback Control of Hormones The majority of endocrine glands operate under negative feedback systems Information regarding the hormone level or its effect on target cells is “fed back” to the hypothalamus or pituitary gland to regulate the production of the hormone

Feedback Control of Hormones

The majority of endocrine glands operate under negative feedback systems

Information regarding the hormone level or its effect on target cells is “fed back” to the hypothalamus or pituitary gland to regulate the production of the hormone

Control of Blood Glucose Levels (sugar) When you have just eaten & your blood glucose levels are high, your pancreas releases the hormone insulin Insulin signals liver & muscle cells to take in glucose, thus lowering blood glucose level When blood glucose levels become too low, the pancreas releases the hormone glucagon Glucagon binds to liver cells, signaling the release of stored glucose

Control of Blood Glucose Levels (sugar)

When you have just eaten & your blood glucose levels are high, your pancreas releases the hormone insulin

Insulin signals liver & muscle cells to take in glucose, thus lowering blood glucose level

When blood glucose levels become too low, the pancreas releases the hormone glucagon

Glucagon binds to liver cells, signaling the release of stored glucose

Glucose Feedback Loop Blood Glucose Blood Glucose HIGH LOW Glucagon Insulin pancreas liver Glucose Target tissue Glucose release secrete secrete stimulates stimulates stimulates absorption absorption

Hormone Action 2 Basic types of Hormones: 1. Steroid hormones = made from lipids (fats) Diffuse freely into cells thru the plasma membrane Then travel to the cell nucleus where thy activate the production of mRNA mRNA then produces the required proteins

Hormone Action

2 Basic types of Hormones:

1. Steroid hormones = made from lipids (fats)

Diffuse freely into cells thru the plasma membrane

Then travel to the cell nucleus where thy activate the production of mRNA

mRNA then produces the required proteins

Steroid Hormones

2. Amino Acid hormones = made from amino acids Don’t diffuse easily through the plasma membrane Must bind to receptors in the plasma membrane of target cells to enter the cell Once inside they activate enzymes which will alter the behavior of other molecules in the cell

2. Amino Acid hormones = made from amino acids

Don’t diffuse easily through the plasma membrane

Must bind to receptors in the plasma membrane of target cells to enter the cell

Once inside they activate enzymes which will alter the behavior of other molecules in the cell

Amino Acid Hormones

Adrenal Hormones and Stress Adrenal glands play an important role in preparing your body for stressful situations. Adrenal glands are located on top of the kidneys and consist of two parts 1. Outer Portion : secretes steroid hormones that help the body combat stresses by raising blood pressure Ex: fright, temperature extremes, bleeding, infection, even test anxiety

Adrenal Hormones and Stress

Adrenal glands play an important role in preparing your body for stressful situations.

Adrenal glands are located on top of the kidneys and consist of two parts

1. Outer Portion : secretes steroid hormones that help the body combat stresses by raising blood pressure

Ex: fright, temperature extremes, bleeding, infection, even test anxiety

2. Inner Portion : secretes two amino acid hormones Epinephrine (sometimes called “adrenaline”) & Nonepinephrine These hormones increase heart rate, blood pressure, & rate of respiration They increase efficiency of muscle contraction & increase blood sugar levels * You may have experienced these symptoms if you have ever had to perform in front of a large audience and had an “adrenaline rush”

2. Inner Portion : secretes two amino acid hormones

Epinephrine (sometimes called “adrenaline”) & Nonepinephrine

These hormones increase heart rate, blood pressure, & rate of respiration

They increase efficiency of muscle contraction & increase blood sugar levels

* You may have experienced these symptoms if you have ever had to perform in front of a large audience and had an “adrenaline rush”

Thyroid and Parathyroid Hormones The Thyroid Gland: Located in the neck Regulates metabolism, growth, and development Main metabolic & growth hormone of the thyroid is thyroxine Thyroxine affects the rate at which the body uses energy and determines your food intake requirements Thryroid also secretes calcitonin Calcitonin regulates calcium levels in the blood by causing an increase in the release of calcium when necessary

Thyroid and Parathyroid Hormones

The Thyroid Gland:

Located in the neck

Regulates metabolism, growth, and development

Main metabolic & growth hormone of the thyroid is thyroxine

Thyroxine affects the rate at which the body uses energy and determines your food intake requirements

Thryroid also secretes calcitonin

Calcitonin regulates calcium levels in the blood by causing an increase in the release of calcium when necessary

The Parathyroid Hormones Parathyroid glands: are attached to the thyroid gland and are involved in mineral regulation Ex: they regulate the absorption of calcium, phosphate, magnesium, etc.

The Parathyroid Hormones

Parathyroid glands: are attached to the thyroid gland and are involved in mineral regulation

Ex: they regulate the absorption of calcium, phosphate, magnesium, etc.

* Hormones that are associated with the endocrine system are responsible for controlling many different functions in your body. * Different hormones may play more important roles during some periods in your life than others.

* Hormones that are associated with the endocrine system are responsible for controlling many different functions in your body.

* Different hormones may play more important roles during some periods in your life than others.