Human Nutrition Chapter 3

Chapter 3 of human nutrition

Atoms

what are the basic building blocks of matter?

Elements

these are substances that cannot be broken down into simpler substances

Molecules

the smallest units of a substance that retain the chemical properties of that substance and can be composed of one or more atoms of the same or different elements

Organelles

specialized structures within a cell that preform special functions such as energy production

Tissues

collections of similar cells that perform a specific function in the body

Organs

Structures composed of two or more types of tissue that work together to perform a specific function

Organ systems

a collection of organs that work together to perform a specific function or functions in the body

Digestion and Absorption

what are the two main functions of the Gastrointestinal system?

Digestion

breaking down food into smaller particles that can be used by the body. Facilitated by the release of enzymes

Absorption

the GI system takes nutrients into the bloodstream, this occurs primarily in the small intestine

Mechanical Digestion

the physical breakdown of food into smaller pieces to prepare it for further digestion

Chemical Digestion

the process by which food is broken down through the action of digestive enzymes

the mouth

where does mechanical digestion primarily take place?

The stomach and small intestine

where does chemical digestion primarily take place?

Carbohydrates

the mouth is the first part of the GI tract and is where ___________ first start to be digested?

Esophagus

a muscular tube that connects the mouth to the stomach and uses a series of contractions known as peristalsis to move food along

Stomach

a large muscular sac that mixes and grinds food with digestive enzymes to further break the food down

small intestine

a long narrow tube that is the main site of nutrient absorption. It is lined with tiny finger-like projections called villi

Large intestine

a wide short tube that absorbs water and excretes indigestible food in the form of feces

Gut wall

the inner lining of the GI tract that is composed of several layers of tissue

absorbing nutrients into the bloodstream

what is the first layer of the gut wall responsible for?

structural support

what is the second layer of the gut wall responsible for?

contractions and relaxation

what is the third and outermost layer of the gut wall responsible for?

Transit time

the amount of time it takes food to travel through the gastrointestinal system

Diet, age, hydration, medications, activity level, medical conditions

what are some things that affect transit time?

Enzymes

these break down specific types of nutrients such as carbs, proteins and fats

amylase

what enzymes digests carbohydrates?

protease

what enzyme digests protein?

lipase

what enzyme digests fats?

Bicarbonate

this helps to neutralize stomach acid and protect the lining of the stomach

Mucus

this helps to lubricate the wall of the gut and protect it from digestive juices

Electrolytes

includes sodium, potassium, chloride with help maintain the correct acid-base balance

Hormones

secretin, cholecystokinin, and gastrin are what?

water

this helps to dilute digestive juices and make them less concentrated

Antimicrobial substances

these help to protect the gut from harmful bacteria and other pathogens

Mucosal cells

mucus is a thick slippery substance that is secreted by what?

protect the gut wall

what is the main function of mucus?

biological catalyst

an enzyme is a type of protein that acts as a _____ ______ increasing the amount of time it takes for chemical reactions to occur in the body

speed up reactions

what does a catalyst do?

Salivary amylase

what enzyme breaks down carbs and is secreted by the salivary glands in the mouth

Rennin

this enzyme is involved in the coagulation of milk, it is found in the stomach

Pepsin

an enzyme that breaks down proteins, secreted by the stomach

Trypsin

an enzyme that breaks down proteins is is secreted by the pancreas

Chymotrypsin

an enzyme that breaks down proteins it is secreted by the pancreas

Pancreatic amylase

this enzyme breaks down carbs

pancreatic lipase

this enzyme breaks down fats

sucrase

this enzyme breaks down sucrose (table sugar)

lactase

this enzyme breaks down lactose into glucose and galactose

glucose and galactose

lactase breaks down lactose into what?

Maltase

this enzyme breaks down maltose into glucose it is secreted by the small intestine

Gastrin

this hormone is produced by G cells in the stomach lining. It stimulates the release of gastric acid

Somatostatin

a hormone produced by D cells in the stomach and small intestine. It regulates the secretion of gastrin

Secretin

a hormone produced by S cells in the small intestine it stimulates the release of bicarbonate. This hormone also stimulates the release of water into the small intestine

Cholecystokinnin (CCK)

a hormone produced in the small intestine that stimulates the release of bile from the gallbladder, as well as stimulates contraction of the gallbladder

epiglottis

a flap of cartilage located at the base of the tongue that helps prevent food from entering the trachea and lungs when we swallow

esophageal sphincter

a valve which prevents contents in the stomach from flowing back up into the esophagus

saliva

this is produced by glands in the mouth and contains water, mucus and electrolytes. It helps to moisten food and make is softer. Making it easier to chew and swallow

Lysozyme

an enzyme found in saliva its primary function is to protect the body against infection by breaking down the cell wall of bacteria

burst

when a lysozyme encounters a bacteria it severs the bond between the amino acid and the sugar causing the bacteria to do this

nervous system

what system is esophageal peristalsis regulated by?

a temporary storage reservoir for food

the stomach serves this function (other than digestion)

HCL

pepsin is activated by this (in the stomach)

intrinsic factor

a protein produced by the stomach lining that is responsible for the proper absorption of vitamin b12

smooth muscles

the role of these in the stomach is to help contract and mix food during the digestive process

chyme

partially digested food is known as this

Type of food, medical conditions, amount of food, hormones.

What can affect gastric emptying?

diabetes

medical conditions such as this can affect gastric emptying

insulin and glucagon

give an example of a hormone that may affect the rate of gastric emptying

Bile

this helps in the digestion of fats and fat soluble vitamins. The liver produces this continuously

emulsifies them

bile does this to fats

duodenum, jejunum and illeum

what are the three main parts of the small intestine?

duodenum

receives digestive secretions from the pancreas and the liver via the bile duct and the stomach

jejunum and illeum

the longest and final section of the small intestine where the majority of nutrient absorption occurs

villi

the walls of the small intestine is lined with tiny finger like protrusions called what?

villi and microvilli

______ __and__ _______ work by increasing the surface area of the small intestine to help absorb more nutrients

Bicarbonate, mucus, pancreatic amylase, lipase, trypsin, chymotrypsin

what are the secretions found in the small intestine?

the circular folds (plicae ciculares)

structural features of the small intestine that help to increase its surface area for more efficient absorption of nutrients (other than villi/microvilli)

segmentation

a series of rhythmic contractions and relaxations of the muscles in the intestinal wall that knead and mix food, bile and digestive juices to promote thorough mixing and maximize absorption

diffusion

the passive movement of molecules from high to low concentration

facilitated diffusion

involved the movement of molecules down a concentration gradient and is facilitated by transport proteins

active transport

movement of molecules against a concentration gradient from low to high concentration

co-transport

involves the simultaneous movement of two or more substances across the cell membrane with the energy generated by the primary transport of one substance being used to move other substances

absorb water, waste storage and elimination

what are some functions of the colon?

Microbiota

the collective community of microorganisms including viruses, bacteria, fungi and protozoa that live in the human body

Production of vitamins and other essential nutrients, competition with pathogens, regulation of immune system, metabolic regulation

what are some of the functions of the Microbiota?

Probiotics

support digestive health and are often found in the gut. They may be referred to as “good bacteria”

prebiotics

a type of dietary fiber that serves as food for the beneficial bacteria in the gut.

Dysbiosis

an imbalanced state of the gut microbiome characterized by a decrease in beneficial microoganisms and an increase in harmful ones.

IBD,IBS, Obesity, allergies, Depression, Anxiety, Autoimmune diseases

what are some diseases associated with dysbiosis?

H. Pylori

what is the main causative factor of peptic ulcers?

peptic ulcers

open sores that form in the inner lining of the stomach and the first part of the small intestine known as the duodenum

NSAID’s

the excessive use of these drugs can contribute to the formation of peptic ulcers

bleeding or perforation of the stomach wall, malnutrition and death

what can happen if peptic ulcers are left untreated?

Antibiotics and acid reducing medications

what are some common treatments for peptic ulcers?

Hiatus hernia

a condition in which part of the stomach bulges up into the chest through an opening in the diaphragm

sliding hiatus hernia

the entire stomach herniates into the chest

paraoesophgeal hiatus hernia

only a part of the stomach herniates into the chest

Xerostomia

dry mouth is also known as

Dry mouth (xerostomia)

a condition in which the salivary glands of the mouth do not produce enough saliva to keep the mouth moist

GI tract cancers

High intake of red meats and processed meats, low intake of fruit and veggies, high calorie, high fat, alcohol and tabbacco use have been associated with an increased risk of what disease?