Biology 20 - Digestive, Circulatory, and Respiratory Systems

Anatomy

The study of the structure of living organisms, including their systems and organs

Physiology

The study of the functions an organism performs

Constraints on Animal Form

• Physical laws

• Evolutionary history

• DNA/developmental

Body Tissues

• Epithelial tissue

• Connective tissue

• Muscle tissue

• Nervous tissue

Epithelial Tissue

Covers the body and lines the organs, providing protection

Glandular Epithelia

Epithelia that absorbs or secretes chemicals as part of establishing a barrier

Mucous Membranes

Tissue that secretes mucus to lubricate and moisten organs/organ systems

Simple Epithelium

Epithelial tissue that is one cell thick

Stratified Epithelium

Epithelial tissue that is multiple cells thick

Connective Tissue

Tissue that binds and supports other tissues

Collagenous Fibres

Inelastic connective tissue composed of collagen

Elastic Fibres

Stretchy connective tissue composed of elastin

Reticular Fibres

Branching, woven fibers composed of collagen

Fibroblasts

Secretes the proteins of extracellular fibers

Macrophages

Amoeboid cells that remove foreign particles and dead cells via phagocytosis

Muscle Tissue

Tissue composed of cells capable of contraction

Nervous Tissue

Tissue that senses stimuli and sends signals

Mesenteries

Sheets of connective tissue that suspends organs in fluid-filled body cavities

Thoracic Cavity

Cavity housing the heart and lungs in mammals

Abdominal Cavity

Cavity housing the digestive and reproductive organs in mammals

Bioenergetics

The flow of energy through an organism

Metabolic Rate

The amount of food an organism uses for energy in a fixed amount of time

Endotherm

An organism that warm itself through metabolic processes

Ectotherm

An organism that is warmed by the environment

Basal Metabolic Rate (BMR)

The rate of metabolism for a resting, non-growing endotherm

Standard Metabolic Rate (SMR)

The rate of metabolism for a resting, non-growing ectotherm at a fixed temperature

Metabolic Rate Factors

• Age

• Sex

• Body/environmental temperatures

• Quantity & quality of food

• Oxygen availability

• Time of day

• Hormone balance

Homeostasis

The bodily state of balance

Digestive System

The system responsible for breaking down food and absorbing nutrients into the bloodstream

Suspension Feeder

An organism that filters small food particles out of water

Substrate Feeder

An organism that lives in or on their food source and consumes it throughout the duration of its life

Fluid Feeder

An organism, often parasite, that sucks nutritious fluids from a host organism

Bulk Feeder

An organism that ingests large chunks of food

Malnourished

When an organism does not have enough access to essential nutrients

Vitamins

Organic molecules that the body needs in small amounts

Minerals

Inorganic molecules that the body needs in small amounts

Ingestion

Process of bringing food into the digestive system

Digestion

Breaking down food small enough to be absorbed, achieved through enzymatic hydrolysis

Intracellular Digestion

Digestion occurring within cells when vacuoles containing food particles fuse with lysosomes

Extracellular Digestion

Digestion that occurs outside of cells in specialized body compartments

Gastrovascular Cavity

A simple digestive system with a single opening where food enters and exits

Alimentary Canal

A digestive system with a separate entrance and exit

Mechanical Digestion

Physically breaking up food (e.g. mastication)

Peristalsis

Mechanical digestion from the squeezing of muscles

Chemical Digestion

Digestion of food with chemicals such as enzymes and acids

Oral Cavity

The entrance to the digestive system (often the entrance to the alimentary canal)

Salivary Amylase

An enzyme prevalent in saliva for the digestion of starch and glycogen

Tongue

A muscle for the manoeuvring of food in the mouth to form a bolus

Bolus

A chewed and lubricated mass of food that passes through the digestive system after the mouth

Epiglottis

A cartilaginous flap that prevents food from entering the trachea

Esophagus

A tube that moves food from the oral cavity to the stomach through peristalsis

Stomach

An organ composed of strong muscles for mechanical digestion, which also employs chemical digestion with hydrochloric acid and pepsin

Peptic Ulcer

An open sore in the stomach or small intestine

Upper Esophageal Sphincter

A muscular ring at the top of the esophagus that helps to prevent air from entering the esophagus

Lower Esophageal Sphincter

A muscular ring at the bottom of the esophagus that helps to prevent stomach acid from entering the esophagus

Pepsin

An enzyme part of the gastric juice in the stomach that plays a role in hydrolyzing proteins, functioning in an ideal pH of 2 where it is activated by hydrochloric acid

Pepsinogen

The inactive form of pepsin which is produced by chief cells for employment in the stomach

Acid Chyme

The nutrient-rich fluid that is produced from the mechanical and chemical digestion of food

Pyloric Sphincter

A muscular ring where the stomach connects with the small intestine

Mucus Cells

Cells within the stomach that secrete mucus for the moistening and lubrication of the stomach

Chief Cells

Cells within the stomach that produce pepsinogen

Parietal Cells

Cells within the stomach that produce hydrochloric acid (HCl)

Gastric Rugae

Folds along the stomach lining that increases the surface area of the stomach, also allowing for the expansion and contraction of the muscles

Small Intestine

The organ where most nutrients are absorbed into the circulatory system

Duodenum

The first section of the small intestine, which is about ~25 cm long

Bile

An alkaline fluid containing bile salts that aid in the emulsification of fats, produced by the liver

Bile Salt

A steroid acid produced from cholesterol integral in the digestion of lipids

Bile Duct

A canal which carries bile from the liver to the gall bladder

Villi

Fingerlike projections lining the small intestine for increasing surface area for nutrient absorption

Pancreas

An organ that secretes digestive chemicals into the duodenum, such as trypsinogen

Liver

An organ that cleanses blood and produces bile for aiding in the chemical digestion of acid chyme

Gall Bladder

An organ that stores and secretes bile produced by the liver

Gall Stone

A hardened stone of digestive fluids that can form in the gall bladder

Secretin

A hormone produced by the pancreas that is activate by hydrochloric acid that when released into the bloodstream triggers the release of bicarbonate ions (HCO3-) for neutralizing hydrochloric acid

Prosecretin

An inactive form of secretin that is activated by hydrochloric acid

Trypsin

An enzyme produced by the pancreas that breaks down peptide chains into smaller amino acid chains

Trypsinogen

An inactive form of trypsin activated by enteropeptidase

Enteropeptidase

An enzyme responsible for activating trypsinogen into trypsin; AKA enterokinase

Erepsin

An enzyme that breaks down short polypeptide chains into individual amino acids

Lipase

An enzyme that breaks down fats and lipids

Lacteal

A lymphatic vessel in the small intestine which absorbs digested fats

Large Intestine

The organ where remaining nutrients and water is removed while waste is consolidated and compacted for release, also known as the colon

Rectum

The terminal portion of the large intestine that connects the colon to the anus

Anus

The end of the large intestine where food waste is removed from the alimentary canal

Ghrelin

A hormone that causes hunger

Insulin

A hormone that regulates blood sugar levels

Circulatory System

A closed system that distributes nutrients across body cells are removes waste materials, while also regulating heat and fighting foreign organisms

Artery

A blood vessel that carries blood away from the heart, most frequently carrying oxygenated blood with thick walls made of connective tissue, smooth muscle, and the endothelium

Endothelium

A single layer of specialized cells that regulates blood flow and clotting, composing the inner layer of arteries and veins

Atherosclerosis

The degeneration of blood vessels from accumulations of fat deposits on the inner walls

Arteriosclerosis

A group of disorders where blood vessels thicken, harden, or lose elasticity

Coronary Embolism

The blockage of the coronary artery, which can contribute to heart attacks

Aneurysm

A bulge in a weakened blood vessel, usually being an artery

Stroke

An aneurysm that occurs in the brain

Arteriole

A smaller artery that typically branches into capillaries

Autonomic Nervous System (ANS)

The aspect of the nervous system responsible for controlling the diameter of blood vessels

Vasoconstriction

The narrowing of blood vessels by the autonomic nervous system

Vasodilation

The widening of blood vessels by the autonomic nervous system

Precapillary Sphincter

A muscular ring of tissue that regulates blood flow, causing not all arterioles to be fully open at all times

Capillary

A blood vessel that is a single cell thick, where the exchange of nutrients between blood and tissues occur