Ch.3: The Human Body

Levels of Organization (smallest-biggest)

• cell

• tissue

• organ

• organ system

• organism

Anabolism

metabolic pathways that use small, simple compounds to build larger, more complex compounds (requires energy)

Catabolism

metabolic pathways that break down larger compounds into smaller compounds (releases energy)

Aerobic

with oxygen

Anaerobic

without oxygen

Cardiovascular System

Major components

• Heart 

• Blood vessels

• Blood

Functions

• Carries blood

• Regulates blood supply

• Transports nutrients, waste products, hormones, and gases (oxygen and carbon dioxide) throughout the body

• Regulates blood pressure

Lymphatic System

Major Components

• Lymph

• Lymphocytes

• Lymphatic vessels

• Lymph nodes

Functions

• Aids fat absorption

• Maintains tissue fluid balance

• Supports immune system

Difference between Blood & Lymph

• Blood is the fluid of the cardiovascular system. It mainly consists of plasma, red blood cells, white blood cells, and platelets.

• Lymph is the fluid of the lymphatic system. It mainly consists of white blood cells and some fluid that has leaked out of the cardiovascular system.

Hepatic Portal Vein

large vein that carries nutrient-rich blood from the gastrointestinal tract directly to the liver

Urinary System

Major components

• Kidneys

• Urinary bladder

• Ducts that carry urine

Functions

• Removes waste products from the blood and forms urine

• Regulates blood acid/base (pH) balance, overall chemical balance, and water balance

• Kidneys participate in activation of vitamin D (important for bone health)

• Kidneys can convert amino acids to glucose during times of fasting or starvation

Nervous System

Major components

• Brain

• Spinal cord

• Nerves

• Sensory receptors

Functions

• Senses information about food

• Directs actions related to selection, preparation, and intake of food

• Neurotransmitters are made of amino acids.

• Sodium and potassium are involved in the transmission of nerve impulses

• relies on glucose to function

Endocrine System

Major components

• Endocrine glands (pituitary, thyroid, and adrenal glands)

• Hypothalamus

• Pancreas

Functions

• Regulates metabolism, growth, reproduction, and many other functions by producing and releasing hormones

Cholecystokinin

regulates the movement of food through the GI tract and stimulates the release of bile and pancreatic juice into the small intestine

Insulin & Glucagon

regulate blood glucose level

Ghrelin

helps to regulate energy intake and body weight by stimulating hunger

Leptin

helps to regulate energy intake and body weight by reducing hunger

Immune System

Major components

• White blood cells

• Lymph vessels and nodes

• Spleen

• Thymus gland

• Other lymph tissues

Functions

• Provides defense against pathogens

• Formation of white blood cells

Accessory Organs to the GI Tract

• liver

• gallbladder

• pancreas

Lower Esophageal Sphincter (cardiac sphincter)

prevents backflow of stomach contents into the esophagus

Pyloric Sphincter

controls the passage of chyme from the stomach into the small intestine

Sphincter of Oddi

controls the flow of pancreatic juice and bile from the pancreas and gallbladder, respectively, into the small intestine

Ileocecal Sphincter

prevents the backflow of feces from the large intestine into the small intestine

Anal Sphincter

controls the excretion of feces from the large intestine

Mechanical Digestion

chewing, mixing

Chemical Digestion

breakdown of food matter into smallest components so that it can be absorbed

Motility

in general, movement of food matter through the GI tract

Peristalsis

a coordinated muscular contraction used to propel food down the gastrointestinal tract (from the top of the esophagus to the anus)

Chyme

mixture of partially digested food and digestive juices in the stomach or small intestine

Small Intestine

• Duodenum: first section; bile and pancreatic juice are secreted into this segment of the small intestine

• Jejunum

• Ileum

Function of Liver

produces bile, which contains emulsifiers and some waste products, removes some metabolic waste products

Function of Gallbladder

stores bile

Function of Pancreas

• Endocrine functions: manufactures insulin and glucagon, which are two hormones that regulate the amount of glucose in the blood

• Exocrine (digestive) functions

  • Produces digestive enzymes that digest carbohydrates, lipids, and proteins

  • Produces bicarbonate, which neutralizes chyme as it moves from the stomach into the small intestine

Large Intestine

• Cecum

• Ascending colon

• Transverse colon

• Descending colon

• Sigmoid colon

Microbiota

community of microorganisms living in a particular region, such as the GI tract (the gut microbiota)

Microbiome

entire collection of microorganisms, their genes, and their environment

Probiotic

live microorganisms that, when administered in adequate amounts, confer health benefits on the host (i.e., human)

Prebiotic

food for the microorganisms that reside in the large intestine; administering prebiotics can change the composition and/or activity of the gut microbiota to benefit the host

Symbiotic

combination of pro- and prebiotics taken to confer health benefits on the host

Postbiotics

metabolic byproducts of the microorganisms that colonize the human body; some postbiotics influence human health

Paraprobiotics

inactivated cells or cell extracts of probiotic microorganisms that may confer health benefits for humans

Major sites of Nutrient Storage

• Adipose tissue: fat (in the form of triglycerides)

• Bone: minerals

• Liver: vitamins, minerals, glycogen, fat

• Muscles: glycogen, fat

• Glands: minerals

• Blood: small amounts of glucose, amino acids, fatty acids, vitamins, and minerals

Constipation

• infrequent bowl movements

• alleviate by taking fiber and fluid