Gastrointestinal anatomy and physoilogy, intro to medical pathalogy and histology, cardiovascular physical examtination and ECG

What is the gastrointestinal (GI) tract and what are its main regions and functions?

The GI tract is a continuous, muscular tube that extends from the mouth to the anus. Its main function is digestion and absorption. Main regions include: Mouth (mechanical and chemical digestion), Oesophagus (transports food), Stomach (acid and enzyme breakdown), Small Intestine (digestion and absorption), and Large Intestine (water absorption and faeces formation).

What are the four layers of the GI tract wall and their roles?

1. Mucosa: Absorption and secretion; 2. Submucosa: Contains vessels and nerves; 3. Muscularis externa: Smooth muscle that moves content; 4. Serosa: Protective outer covering.

Describe the role of the mouth and oesophagus in digestion.

The mouth performs mechanical digestion (chewing) and chemical digestion (salivary amylase). The oesophagus moves food to the stomach via peristalsis. The epiglottis prevents food from entering the trachea. Sphincters regulate food movement.

What functions does the stomach perform during digestion?

The stomach mixes food with gastric juices, secretes hydrochloric acid and pepsin for protein digestion, and controls food entry and exit using sphincters.

What are the three parts of the small intestine and their specific functions?

Duodenum receives bile and enzymes; Jejunum absorbs most nutrients; Ileum absorbs vitamin B12 and bile salts.

What are the functions of the large intestine?

The large intestine reabsorbs water and electrolytes, forms and stores faeces, and contains gut microbiota. It includes the caecum, colon, rectum, and anus.

What are the main accessory digestive organs and their roles?

The liver produces bile and processes nutrients. The gallbladder stores and releases bile. The pancreas secretes digestive enzymes and hormones like insulin and glucagon.

How is GI motility regulated and what are peristalsis and segmentation?

GI motility is regulated by the enteric nervous system and autonomic input. Peristalsis is the wave-like motion that moves food. Segmentation mixes contents locally.

How are carbohydrates digested and absorbed?

Digestion starts in the mouth with salivary amylase and continues in the small intestine using pancreatic amylase. Carbohydrates are broken down into monosaccharides and absorbed into the bloodstream.

Describe lipid digestion and how fats are absorbed.

Bile emulsifies fats into micelles. Pancreatic lipase breaks down fats. Fatty acids are absorbed, reassembled into triglycerides, and transported as chylomicrons into lymph.

How is protein digested and absorbed in the GI tract?

Protein digestion begins in the stomach with pepsin and continues in the small intestine with enzymes like trypsin and brush border enzymes. Amino acids are absorbed into the blood.

What is medical pathology and why is it important?

Medical pathology involves the study and diagnosis of disease using tissue and fluid samples. It is crucial for accurate diagnosis and guiding treatment.

What are assays and how are they classified?

Assays are lab tests that measure the presence or function of substances. They are classified as colorimetric (based on color changes) or molecular (detect DNA/protein).

What are examples of colorimetric assays and how do they work?

The BCA assay measures total protein via color change. ELISA uses antibodies and enzymes to detect specific targets based on binding.

What are examples of molecular assays and what do they detect?

PCR amplifies DNA sequences to detect specific genes. Western blot identifies proteins based on size and antibody recognition.

What is histology and how are tissue samples prepared?

Histology is the microscopic study of tissues. Tissues are fixed (preserved), sectioned (sliced), and stained for examination under a microscope.

Why are staining techniques important in histology?

Staining provides contrast to identify cells and tissue structures, which is crucial for diagnosis and research.

Describe Haematoxylin & Eosin (H&E) staining.

Haematoxylin stains acidic structures (e.g., nuclei) blue-purple. Eosin stains basic structures (e.g., cytoplasm) pink-red. This is the most common histological stain.

What are Nissl and cresyl violet stains used for?

These stains highlight neurons in nervous tissue by binding to rough endoplasmic reticulum. They differentiate neurons from glial cells.

What is Leishman or Wright-Giemsa stain used for?

These stains are used for blood smears to differentiate types of blood cells and can detect parasites.

How do specialised stains and antibodies work in histology?

Specialised stains use antibodies to bind specific proteins or cell markers, enhancing identification of diseases or cellular structures.

How are antibodies produced in the body?

B cells respond to antigens by mutating and producing specific antibodies that bind and neutralise those antigens.

What is immunohistochemistry and why is it powerful?

It uses antibodies to detect specific proteins in tissue samples. It helps visualize disease markers like tau in Alzheimer’s.

What are the basic steps in a cardiovascular physical exam?

1. Inspection; 2. Palpation; 3. Auscultation (Percussion is often omitted in cardiovascular exams).

What do you assess during inspection in a cardiac exam?

Look for chest shape, breathing pattern, ability to speak, hand color, clubbing of fingers, and limb swelling.

What valve areas do you palpate during a cardiovascular exam?

Mitral: 5th intercostal, midclavicular; Tricuspid: left 4th–5th costosternal; Pulmonary: left 2nd ICS; Aortic: right 2nd ICS.

What are “thrills” in cardiac palpation?

Thrills are vibrations felt over the chest wall, suggesting abnormal blood flow, often due to valve dysfunction.

What other assessments are done during palpation?

Check temperature of hands, capillary refill (press fingertip for 3–5 seconds), and radial pulse using index and middle fingers.

What is auscultation and what areas are listened to?

Auscultation involves using a stethoscope to listen to heart sounds over the same valve areas used in palpation.

What is an ECG and what are its types?

An ECG records the heart’s electrical activity. Common types include 3-lead, 5-lead, and 12-lead ECGs.

Where are ECG electrodes placed?

Limb leads: RA (right arm), LA (left arm), RL (right leg), LL (left leg). Chest leads are placed at specific intercostal spaces around the chest.