Regulation of Body Temperature

The process by which the body maintains a stable internal temperature.

Specialized nerve endings that detect changes in temperature.

A region in the brain that plays a key role in regulating body temperature and other vital functions.

The network of sensors, pathways, and effectors involved in maintaining internal temperature.

The pathway that carries signals from sensors to the control center.

The vagal nerve stimulates the salivary glands, causing a release of saliva. This process helps lubricate the mouth and food for swallowing.

The stimulation triggers the release of saliva from the salivary glands. Saliva helps break down food and lubricates the mouth for swallowing.

There are two types: intrinsic glands (found within the mouth) and extrinsic glands (outside the mouth). Both contribute to saliva production.

Intrinsic glands, located within the mouth, provide a constant low rate of saliva secretion for lubrication.

Extrinsic glands, located outside the mouth, provide bursts of saliva when needed, such as during chewing or swallowing.

Hormones are chemical messengers that travel through the bloodstream and regulate various bodily functions.

The four main types are:

1. Peptide/Protein Hormones: Made from amino acids, like insulin.
2. Steroid Hormones: Derived from cholesterol, like testosterone.
3. Amines: Derived from amino acids, like epinephrine.
4. Eicosanoids: Derived from fatty acids, like prostaglandins.

A pre-hormone is an inactive precursor molecule that gets converted into an active hormone.

These describe how hormones reach their target cells:

• Endocrine: Hormone travels through the bloodstream to distant targets.
• Paracrine: Hormone acts on nearby cells, not through bloodstream.
• Autocrine: Hormone acts on the same cell that released it.
• Neurocrine: Hormone released by a neuron, travels to target cells through nerve fibers.

These are water-soluble hormones that cannot pass through cell membranes. They bind to receptors on the cell surface.

These are lipid-soluble hormones that can pass through cell membranes and bind to receptors inside the cell.

Hydrophilic hormones bind to receptors on the cell surface, while hydrophobic hormones bind to receptors inside the cell, often in the nucleus.

Insulin is a peptide/protein hormone that regulates blood sugar levels.

A condition, usually caused by impaired salivary secretion, characterized by an abnormally dry mouth.

An autoimmune disorder that primarily affects the salivary and lacrimal glands, resulting in dry mouth (xerostomia) and dry eyes (keratoconjunctivitis sicca).

There are three main types of salivary glands: parotid glands (largest), submandibular glands, and sublingual glands. They all contribute to saliva production.

Salivary glands play a crucial role in swallowing by producing saliva, which lubricates the mouth and food, aiding in bolus formation and passage through the esophagus.

The act of swallowing involves 3 phases: Oral, Pharyngeal, and Esophageal.

A rhythmic muscular contraction that moves food through the esophagus, primarily initiated by the swallowing reflex.

A rare esophageal disorder characterized by incomplete relaxation of the lower esophageal sphincter (LES), leading to difficulty swallowing.

The stomach plays a vital role in digestion by: 1. Storage of food, 2. Mechanical and chemical breakdown of food, 3. Production of intrinsic factor for vitamin B12 absorption.

Gastric glands are found in the stomach lining and consist of several cell types: mucous cells, parietal cells, chief cells, and endocrine cells.

Parietal cells secrete hydrochloric acid (HCl) and intrinsic factor. HCl helps break down food and kill bacteria, while intrinsic factor aids in vitamin B12 absorption.

A hormone produced by endocrine cells in the stomach. It stimulates parietal cells to release gastric acid.

A chemical released from mast cells in the stomach that stimulates parietal cells to increase acid secretion.

Gastric secretion is regulated by a complex interplay of neural, hormonal, and paracrine factors. Vagal nerve stimulation and gastrin increase acid release, while somatostatin and secretin decrease acid release.

The myenteric plexus is a network of nerves located between the muscle layers of the digestive tract. It contains sensory neurons, interneurons, and motor neurons.

The myenteric plexus regulates gastrointestinal motility (muscle contractions) and transit of food through the digestive tract.

The breakdown of proteins into smaller peptides and amino acids, which are then absorbed into the bloodstream.

Protein that originates from within the body, such as from sloughed intestinal cells or digestive enzymes.

The process by which amino acids and peptides are transported from the gut lumen into the bloodstream.

A protein transporter in the intestinal wall that moves dipeptides and tripeptides into the cell.

Specialized tissues in the small intestine that play a key role in immune response and protection against harmful substances in the gut.

Lipase is an enzyme that breaks down fats into fatty acids and glycerol, making them easier to digest and absorb.

Peptidases are a group of enzymes that break down proteins into smaller peptides and amino acids, which can be absorbed by the body.

Chymotrypsin is a digestive enzyme that specifically breaks down proteins into smaller peptide chains. It's produced in the pancreas and activated in the small intestine.

Pancreatic amylase is an enzyme that breaks down complex carbohydrates (starches) into simpler sugars like maltose, which can be absorbed by the body.

The small intestine is the primary site for digestion and absorption of nutrients. It's where most of the breakdown of food happens and where digested nutrients enter the bloodstream.

The four motility functions are: (1) mixing, (2) propulsion, (3) segmentation, and (4) peristalsis. These movements help mix food with digestive juices, move it along the intestine, and increase the surface area for absorption.

Brunner's glands secrete alkaline mucus that helps neutralize the acidic chyme from the stomach, protecting the small intestine lining.

Paneth cells release lysozyme, an antimicrobial enzyme that helps protect the small intestine from harmful bacteria.

The ileocecal valve controls the flow of digested material from the small intestine to the large intestine. It prevents backflow and helps keep the contents moving forward.

The large intestine primarily absorbs water and electrolytes, compacts waste material, and stores feces before elimination. It also plays a role in the production of vitamins and the regulation of water content in the body.

The hypothalamus acts like the body's thermostat, receiving input from temperature sensors and triggering responses to maintain a stable internal temperature. It controls shivering, sweating, and other mechanisms to keep the body within a safe range.

Thermoreceptors are specialized nerve endings that detect changes in temperature, both internally and externally, and send signals to the brain.

The resting metabolic rate (RMR) is the amount of energy the body uses at rest to maintain basic functions like breathing, heart beating, and brain activity.

Heat production mainly occurs through metabolic processes, particularly during muscular activity, but also during other basic functions.

Heat elimination primarily occurs through the skin via sweating, radiation, convection, and conduction. These processes help dissipate excess heat, preventing overheating.

The digestive tract has four main layers: mucosa, submucosa, muscularis, and serosa. Each layer has a specific function in digestion and absorption.

The innermost layer of the digestive tract. Comprises an epithelium, lamina propria, and muscularis mucosae. Its role includes absorption, secretion, and protection.

The uppermost layer of the mucosa, composed of specialized cells that are crucial for absorption and secretion.

Epithelial cells of the small intestine, responsible for absorbing nutrients from digested food.

Finger-like projections (villi) and small pockets (crypts) within the small intestine that increase surface area for absorption.

A layer of loose connective tissue beneath the epithelium, containing blood vessels, nerves, and lymphatic tissue.

A thin layer of smooth muscle within the mucosa, responsible for subtle movements that aid digestion and absorption.

The outermost layer of the digestive tract, a protective membrane that covers the organ and reduces friction.

Salivary glands are organs that produce saliva, a fluid crucial for digestion and oral hygiene. There are three main types: parotid, submandibular, and sublingual.

Saliva lubricates the mouth and food, aiding in the formation of a food bolus, which is easier to swallow and transport to the esophagus.

The myenteric plexus is a network of nerves located in the walls of the digestive tract. It controls the movement of food through the digestive system.

The stomach stores food, mixes it with gastric juices, and breaks down proteins into smaller molecules. It also produces intrinsic factor, essential for vitamin B12 absorption.

The large intestine primarily absorbs water and electrolytes. It also compacts waste material and stores feces before elimination.

Endocrine: through bloodstream to distant targets. Paracrine: acts on nearby cells. Autocrine: acts on the same cell that released it. Neurocrine: released by a neuron, travels to target cells through nerve fibers.

The process of creating hormones from precursor molecules, often involving multiple steps and enzymes.

Lipids that are produced within the body, such as phospholipids and cholesterol.

Pancreatic enzymes, such as lipase, break down fats into smaller molecules like fatty acids and glycerol, allowing for easier absorption.

Fatty acids are absorbed by the small intestine, forming micelles, which are then transported into the lymphatic system and eventually into the bloodstream.

Pancreatic nucleases break down nucleic acids (DNA and RNA) into smaller units like nucleotides, which are then absorbed.

Bases from nucleic acid digestion are absorbed through active transport, requiring energy to move them across cell membranes.

Vitamin D helps regulate calcium absorption in the small intestine, ensuring sufficient calcium for bone health and other functions.

Parathyroid hormone (PTH) activates vitamin D, increasing calcium absorption in the gut and bone resorption.

Factors influencing vitamin D absorption include sunlight exposure, dietary intake, and the regulation of PTH.

A cluster of three structures found in the liver: the portal vein, the hepatic artery, and the bile duct. These structures are essential for the liver's functions.

Sinusoids are blood-filled spaces in the liver that allow blood from the portal vein and hepatic artery to mix and come into contact with hepatocytes (liver cells). This facilitates exchange of nutrients, oxygen, and waste products.

Kupffer cells are specialized macrophages located within the liver sinusoids. They engulf and destroy bacteria, parasites, and other foreign substances in the blood, acting as the liver's immune defense.

Bile is a fluid produced by the liver that helps in the digestion of fats. It is composed of bile salts, cholesterol, and bilirubin.

Primary bile acids are produced in the liver from cholesterol. These acids are then converted into secondary bile acids by bacteria in the small intestine.

The gallbladder is a small organ that stores and concentrates bile produced by the liver. It releases bile into the small intestine when needed.

A liver lobule is a functional unit of the liver. It is divided into three zones based on blood flow and oxygen concentration. Zone 1 is closest to the portal triad and receives the highest concentration of oxygen, while zone 3 is furthest from the portal triad and has the lowest oxygen concentration

A condition where toxins from the liver, normally processed by the liver, build up in the bloodstream and affect the brain, leading to confusion, lethargy, and other neurological symptoms.

The liver plays a crucial role in detoxifying harmful substances in the blood. It breaks down drugs, alcohol, and other toxins through various metabolic processes, making them less harmful.

Primary bile acids are produced in the liver from cholesterol. They are then converted into secondary bile acids by bacteria in the small intestine.