Medical Practice Notes

Physiology and Anatomy

• Physiology: Study of the body's functions, including individual structures and organs.
• Anatomy: Study of the body's structures, form, and relationships.
  • Macro-anatomy: Study of structures visible without a microscope, either by system or location.
  • Micro-anatomy: Study of tissues and cells using a microscope.

Systems of the Body

• Skeleton: Bones providing firmness.
• Articulatory system: Joints.
• Muscles: Coordinate with the skeleton for locomotion.
• Digestive system: Specializes in digestion.
• Respiratory system: Supplies oxygen and removes carbon dioxide.
• Urinary system: Maintains chemical composition of blood and eliminates by-products.
• Reproductive system: Specializes in species survival.
• Cardio-vascular system: Heart and blood vessels ensuring food reaches tissues.
• Nervous system: Regulates bodily activities.
• Skin: Protective cover.
• Endocrine glands: Produce hormones to control body chemistry.

Terminology

• Uses international and Latin terms.
  • Anterior: On the front side.
  • Posterior: At the back side.
  • Lateral: Away from the midline.
  • Median: On the midline.
  • Superior: At the top side.
  • Inferior: At the bottom side.
  • External: On the outside.
  • Internal: On the inside.
  • Proximal: Nearer to the body.
  • Distal: Further away.
  • Palmar: Palm of the hand.
  • Plantar: Sole of the foot.
  • Abduction: Moving away from the body.
  • Adduction: Moving towards the body.
  • Flexion: Bending.
  • Extension: Extending.
  • Supination: Turning palm upward.
  • Pronation: Turning palm downward.

Skeleton Terms

• Condyle: Round enlargement at bone ends, usually covered with cartilage.
• Crista: A ridge on a bone.
• Fossa: Excavated area on bone.
• Facet: Articulating surface.
• Foramen: Opening in a bone.
• Process: Projecting part.

Cuttings of the Body

• Sagittal: Divides body into left and right.
• Coronal: Divides body into anterior and posterior.
• Transverse: Divides body into upper and lower.

Body Cavities

• Cranial and vertebral: Contain brain and spinal cord.
• Thoracic: Contains pericardial (heart) and pleural (lungs) cavities.
• Peritoneal: Abdominal (stomach, liver, pancreas, intestinal channel) and pelvic parts, divided from the thoracic cavity by the diaphragm.

Cells and Tissue

• Cells: Basic building units of the body.
• Tissue: Group of similar cells.
• Organ: Formed by a certain amount of tissue.
• System: Formed by a number of organs.
• Cell membrane: Selective transmissible membrane surrounding the cell.
• Environment: Tissue liquid containing glucose, fatty acids, amino acids, mineral salts (sodium, potassium, calcium, chloride), gases (oxygen, carbon dioxide), hormones, enzymes, and residual products (ureum and urinal acid).
• Protoplasm: Basic component of the cell, consisting of nitrogen, sodium, potassium, chloride, carbon, iron, nitrogen, phosphate, and calcium.
• Cytoplasm: Contains the cell nucleus, necessary for life, growth, and reproduction.
• Cell nucleus: Controls cell activities and contains nucleoprotein.
• Chromosomes:
  • Located within the cell nucleus.
  • Number 46 in each cell, except gender cells (spermatozoa).
  • After fertilization, the number of chromosomes is divided into two equal parts, making a total of 46.

Characteristics of a Living Cell

• Assimilation of nutrition.
• Growth and recuperation.
• Reproduction.
• Excretion of residue.
• Ability to move (some cells).

Tissues

• Epithelium tissues: Line or cover organs, offering protection, secretion, or absorption.
  • Simple epithelium tissues: Single layer of cells on a basal membrane.
    • Pavement or flat epithelium: Single layer of flat cells, found in the oesophagus and superficial skin layer. Keratinized in the skin for waterproofing.
    • Stratified cylinder epithelium: Found in the gut, serving as absorbent tissue and secretion of slime.
    • Ciliated epithelium: Found in the trachea (catches dust particles) and Fallopian tubes.
    • Transitional epithelium:
    • Cylinder epithelium: Cells are cylindrical; goblet cells secrete slime, found in the gut.
    • Cubic epithelium: Found in certain glands, such as sweat glands.
  • Compound epithelium tissues: More than one cell layer thick, with the same function as simple epithelium.
    • Stratified or compound epithelium: Cells rest on the basal membrane, with the outer layer depressed. Found in the bladder.
    • Gland epithelium: Secretes saliva, enzymes, etc. Cubic epithelium found in sweat glands.
• Connective tissue:
  • Bone:
    • Forms the skeleton and contains calcium for hardness.
  • Blood:
    • Connective tissue with cells floating in a fluid part.
    • Not stationary and in continuous movement.
  • Tendons and ligaments:
    • Tendons attach muscles to bone.
    • Ligaments support joints.

Muscular Tissue

• Voluntary/striped: Skeleton muscles; contraction is short and powerful.
• Involuntary or smooth: Small muscles with slow contraction; found in the gut and blood veins.
• Heart muscle (miocardium): Powerful contractions, involuntary.

Nerve Tissue

• Consists of nerve fibers and nerve cells.
• Nerve cells: Convey impulses from the brain.
• Nerve stimuli: Conduct in one direction.

Digestive System

• Organs constructed out of tissues with the same function.
• Consists of teeth, saliva glands, oesophagus, liver, stomach, spleen, pancreas, duodenum, transverse colon, jejunum and ileum, ascending colon, appendix, rectum, anal sphincter, anus.
• Additional digestive organs: Pancreas, liver, and saliva glands.
• Begins in the mouth where teeth process food.
• Two sets of teeth:
  • Milk teeth (temporary) without roots, substituted by permanent set at 4-7 years.
  • Permanent teeth: 32 teeth classified as incisors, eye teeth, front molar teeth (premolars), back molar teeth (molars).
• Teeth formula is written as:
  • $\frac{I 2/2, C 1/1, P 2/2, M 3/3} {I 2/2, C 1/1, P 2/2, M 3/3}$
• Incisors cut food, eye teeth tear/undermine food, molars chew food.
• Saliva stimulates muscles for swallowing.
• Food bolus enters the stomach and then the duodenum via the pyloric sphincter.
• Passes to the jejunum and then the ileum, which joins the colon via the ileocecal sphincter.
• Vomiting: Opposite movement, contraction of diaphragm and abdominal muscles.
• Peristalsis: Rhythmic wave-like motion that decelerates when there is food in the gut to increase the mixing of food or forward movement

Digestion and Diet

• Balanced diet consists of:
  • Proteins: Building blocks found in meat, fish, and pods.
  • Carbohydrates: Found in starchy and sugary foods, source of energy.
  • Fats: Animal and plant fats, stored in special fat cells. Can be converted from carbohydrates and proteins.
  • Mineral salts: Necessary for body function (sodium, calcium, potassium for pH balance; calcium for muscle functioning and bone strengthening; iodine for thyroid function).
  • Water: Largest part of body mass, replenished continually.
• Body loses an average of 1200 ml fluid per day.
• Fibre: Helps normalize peristalsis, found in wheat, vegetables, and fruit.
• Vitamins: Necessary for enzyme systems.
  • Vitamin A (Retinol): Found in milk, butter, egg yolk, fish oils, produced in the liver from carotene, found in spinach and carrots. Deficiency causes night-blindness and eye infections.
  • Vitamin B Complex:
    • Vitamin B1 (Aneurine or Thiamine): Found in peas, beans, whole wheat bread, yeast, raw carrots, and cabbage. Deficiency causes nervous system problems and beri-beri.
    • Vitamin B2 (Riboflavine/Lactoflavin): Present in liver, kidneys, and milk. Deficiency causes tenderness of lips and redness of eyes.
    • Vitamin B3 (Nicotinic acid/Nicotinamide/Niacin): Found in the same sources as B1. Deficiency causes pellagra, characterized by disturbances of the skin and psychological disturbances.
    • Vitamin B12 (Cinocobalamin):
  • Vitamin C (Ascorbic acid): Found in acidic fruit, fresh vegetables, and tomatoes.
  • Vitamin D (Calciferol): Occurs naturally in cod liver oil, butter, and eggs. Plays a role in calcium metabolism. Deficiency leads to malformation of bones.
  • Vitamin E (Tocopherol): Present in liver, spinach, and green-colored vegetables. Deficiency leads to premature birth and abortion.
  • Vitamin K (Menaphtone): Necessary for prothrombin formation; deficiency leads to bleeding or haemophilia.

Digestion in the Stomach

• Gastric juice has a low pH due to hydrochloric acid, secreted by some cells.
• Pepsin breaks down protein to polypeptides.
• Food is mixed thoroughly by peristaltic movement.
• Particles of food are released into the duodenum via the pyloric sphincter.

Digestion in the Small Intestines

• Duodenum: Neutralizes acid of gastric juice with gall and alkaline pancreas juice.
• Enzymes obtained from intestinal juice (succus entericus) and pancreatic juice.
• Pancreatic juice: contains trypsin (breaks down raw and cooked starch to amino-acids); pancreas amylase (breaks down to maltose); lipase (breaks down fats to fatty acids and glycerol).
• Intestinal juice: contains invertase (breaks down cane-sugar to glucose); maltase (maltose to glucose); aminopeptidases or erepsin (peptones to amino-acids).

Absorption of Digested Food

• Glucose and amino acids are absorbed directly into the bloodstream via the mucosa and conveyed to the liver.
• Fatty acids and glycerol are absorbed into lacteal tubes, changed to triglycerides, and taken to the veins near the heart via the lymphatic system.
• Excess fat is stored in special fat cells.
• Excess proteins and carbohydrates are also changed to fat and stored.
• Absorption occurs in the duodenum and large intestine.
• Water is absorbed in the large intestine.
• Faeces stimulate the walls of the rectum to contract and the anal sphincter to relax (relieve reflex).

The Breathing System

• Main function is to supply oxygen and remove carbon dioxide.
• External respiration: Exchange of oxygen and carbon dioxide between the lungs and the blood.
• Internal or tissue respiration: Exchange of gases between blood and tissues.

Air Passages

• Nasal cavities, pharynx, larynx, and trachea.
• Bronchi branch out from the trachea in the lungs and further branch into bronchioli.
• Alveoli are air sacs for gas exchange.
• Trachea consists of C-formed cartilage rings.
• Vocal chords are situated in the larynx.

The Lung

• Left lung consists of two lobes; the right lung has three lobes.
• Each lung is surrounded by the pleura.

Respiratory Movements

• Inhaling (inspiration): Diaphragm contracts, inter-rib muscles contract, enlarging the thoracic cavity.
• Exhaling (expiration): Opposite happens.

Unusual Respiratory Movements

• Sighing and yawning are lengthened inspiratory movements.
• Coughing is a powerful expiration.
• Hiccup is a loud inspiration caused by muscle spasms of the diaphragm.

Physiology of Respiration

• Functions of the lungs:
  • Gas exchange between blood and atmosphere.
  • Secretion of hydrogen and other volatile substances.
  • Provision of air to the vocal chords.
• Differences between atmospheric and exhaled air:
  • Atmospheric air: Oxygen 20%, Carbon dioxide 0.4%, Nitrogen 79%.
  • Exhaled air: Oxygen 16%, Carbon dioxide 4%, Nitrogen 79%.
• Gas exchange occurs through diffusion.
• Oxygen is taken up by haemoglobin.
• Carbon dioxide is conveyed in the blood as carbaminohemoglobin and as bicarbonate in the plasma.
• Carbon monoxide is taken up more easily by haemoglobin than oxygen, causing carboxyhemoglobin.

Air Changes in the Nose

• Air becomes 100% saturated with moisture.
• Air is heated up to body temperature.
• Dust particles are removed from the air.