• Author: admin
  • Published: 26th March, 2012
  • Category: Diet
  • Comments: None


Tags: | | | | | | | | | | | | | | |



Keeps skin and mucous membranes healthy. For night vision. Too much damages hair, skin, liver, bone and can cause birth defects Dark green leafy vegies, yellow fruit, liver, milk, eggs.


To release and use energy from carbohydrate foods. Lost with heat, air, cooking, water, meat drippings, when grains are refined. Lost in cooking if bicarb soda is added. Important for heavy drinkers or if a lot of sugar is eaten. Wheatgerm, wholegrains, pork, yeast extract, nuts, legumes.


Growth of new body tissues, healthy skin and eyes. Lost with light (eg. milk bottle left in sun). Lost in cooking if bicarb soda is added. Makes urine bright yellow. Important for heavy drinkers. Milk, liver, kidney, eggs, yeast extract, wholegrain cereals.


For using protein, making red blood cells (RBC). Lost in light, high heat, cooking water. Important for pregnancy, elderly, heavy drinkers, people on certain medications. More than 500mg/day can damage nerves. Banana, avocado, peanuts, meat, chicken, fish, milk, yoghurt, cheese, yeast extracts.


To form RBC, for healthy nervous system. Important for heavy drinkers, people taking large amounts of vitamin C, people who eat no animal products at all (and their breast fed babies). Liver, sardines, oysters, egg yolk, lean meat, milk, dairy products. Only animal products have large amounts of B12.

(Ascorbic acid)

For absorbing iron; healthy teeth, gums, blood vessels. Lost with heat, air, cooking water. Lost in cooking if bicarb soda added. Too much causes diarrhoea, stomach cramps. Citrus fruits, green vegetables, potatoes, tomatoes, paw paw, berry fruits.


Growth and development of bones and teeth. Too much causes vomiting, thirst, headache, hardening of tissues. Important for bedridden elderly and infants not exposed to unfiltered sunlight. Sunlight on the skin makes the body produce its own Vit D. Also found in fatty fish, liver, egg yolks.


Protects cell walls from chemical injury. Keeps RBC healthy. Lost when exposed to light and high heat. Too much causes minor stomach upsets, fatigue, weakness and affects anti-clotting medications. Wheatgerm, vegetable oils, nuts, egg yolk, leafy green vegies, wholemeal cereals.


For normal clotting of blood. Breast milk is a poor source, newborns can’t make their own so an injection is often given at birth to cover them until they can. Cabbage, spinach, cauliflower. Also made in the gut

(Nicotinic acid, Nicotinamide)

To convert food into energy; healthy skin. Lost if food is overcooked. Important for heavy drinkers. Too much causes flushing, tingling, dizziness. Lean meats, fish, poultry, peanuts, wholemeal, cereals, yeast extracts.

(Pantothenic acid)

Healthy nervous system; release of energy from food. Too much causes occasional diarrhoea. Liver, egg yolk, most fish, broad beans, nuts.
Folic Acid


To form RBC, to use protein. Lost with heat, light, cooking water. Lost in cooking if bicarb soda added. Important for pregnancy, elderly, heavy drinkers, people on certain medicines. Spinach, cabbage, avocado, root vegies, grains, nuts.


Helps make fatty acids and glucose. Important for people who eat 8 – 10 raw egg whites daily, people taking long-term high dose antibiotics, heavy drinkers, people with chronic health conditions. Egg yolks, soya beans, wholemeal bread, avocado
Calcium For strong bones and teeth. Needed in blood for healthy functioning of muscles and nerves. Important for children, pregnant and breastfeeding women. Milk, dairy products, sardines, kidney beans, nuts, wholemeal pasta.
Iron Enables RBC to carry more oxygen. Not having enough causes anaemia. Important for adolescent girls, pregnant women, athletes, vegetarians. Breast milk, lean red meat, fish, chicken, green vegetables, cereals


Gastro-Intestinal System (Digestive System)

Tags: | | | | | | | | | | | | | | | | | | | | | | | |

Digestive System organs fall into 2 main groups:

  1. Alimentary canal (GIT) (digesting and absorbing food stuff)
    • Mouth
    • Pharynx
    • Oesophagus
      • About 25cm long
      • Starts at laryngopharynx – passes through diaphragm and ends at stomach
      • Top 1/3 – skeletal muscle
      • Middle 1/3 – mix of skeletal and smooth muscle
      • Bottom 1/3 is smooth muscle only
    • Stomach
      • Varies in size from 15–25 cm long depending on contents
      • The superior (top portion) is continuous with the oesophagus while the inferior (bottom portion) empties into the duodenum
      • Is separated from the small intestine by the pyloric sphincter
      • Divided into 4 regions:
        1. The Cardia – contains mucous cells with some lysozyme secretion
        2. Fundus
        3. Body – 2 cell types: cells that secrete main gastric enzyme – pepsinogen. Cells that secrete HCl and Intrinsic Factor (IF)
        4. Pylorus
      • The rate at which the stomach empties is determined by both the contents of the stomach and the processing that is occurring in the small intestine.
      • a temporary storage tank where the chemical breakdown of proteins is initiated and food is converted to chyme.
    • Small intestine (re-absorption process)
      • Duodenum – approx 25cm long
      • Villi (modified mucosa) increases surface area for absorption
      • Jejunum – approx 1m in length. Joins the duodenum to the ileum (approx 1.6m in length)
      • Is the site of the completion of digestion and absorption of nutrients.
      • Small intestine ends just above the caecum
      • Food takes 3 to 6 hours to complete its digestive path through the small intestine, the site of virtually all nutrient absorption.
      • Most substances required for chemical digestion within the small intestine are imported from the pancreas and the liver.
      • Optimal digestive activity in the small intestine depends on a slow, measured delivery of chyme from the stomach
      • Is the sole site for lipid digestion
      • Absorbs dietary vitamins
    • Large intestine
      • Absorbs water from indigestible food residues and eliminates them as faeces.
      • Has the following subdivisions: cecum, appendix, colon, rectum, and anal canal.
      • Absorbs vitamins B and K
  2. Accessory digestive organs (helpers):
    • Teeth
    • Tongue
    • Gall Bladder - stores and concentrates bile that is not needed immediately for digestion.
    • Salivary glands
    • Liver
    • Pancreas

Function: To convert food into small molecules for transport across the cell membrane, to be used as an energy source by cells.

Digestive System



6 Processes occur:

  1. Ingestion – taking in of food into the mouth
  2. Propulsion – moving food from mouth through the tract
  3. Chemical secretion – from exocrine glands. They secrete enzymes important for:
  4. Digestion – the conversion of large molecules to smaller molecules for:
  5. Absorption – across the wall of the GI tract to blood or lymph vessels, then to other cells of the body
  6. Elimination – undigested materials, eliminated by defecation


2 sorts of digestion:

  1. Chemical digestion - causes the breakdown of large carbohydrates, lipids and proteins
  2. Mechanical digestion – helps chemical digestion. i.e. food is broken up by teeth, swallowed, churned by smooth muscles in stomach and intestine and mixes with enzymes for further breakdown.

Both processes occur in the oral cavity but chemical digestion only really begins there.

Nasal and oral cavity


Tongue and teeth are involved in mechanical digestion. Also involved in taste via taste buds.


  • 8 incisors
  • 4 canines (for cutting and tearing)
  • 8 premolars
  • 12 molars (for crushing and grinding)

Salivary Glands

3 pairs of large salivary glands that secrete saliva:

  • Parotid
    • Located under and in front of ears, between skin and masseter muscle (large muscle involved with chewing)
    • Secretion contains a high content of amylase (enzyme) which begins carbohydrate breakdown
  • Submandibular
    • Beneath the base of the tongue
    • Ducts run either side of the midline of the floor of the mouth, opening just behind the central incisors
    • Secretion has a weak amylase activity but high lysozyme content (enzyme active against bacteria)
  • Sublingual
    • Found under tongue
    • Ducts open into floor of the mouth

Each has its own blood, lymph and nervous supply.


  • 99.5% water, 0.5% solutes (salts such as: chlorides, phosphates, bicarbonates, urea, uric acid, mucin, lysozyme)
  • 1 -1.5L secreted each day


  • Water – dissolves food so it can be tasted, beginning the digestive process
  • Chlorides – activates amylase
  • Bicarbonates and phosphates – act as buffers to keep pH slightly acidic (pH 6.35 – 6.85)
  • Urea and uric acids – are wastes from salivary glands
  • Mucin (+ water) – gives mucous which lubricates the bolus of food
  • Lysozyme – destroys bacteria, therefore protecting against infection and protecting teeth from bacterial decay


  • Once chewed the bolus is moved by contraction of skeletal and smooth muscle from mouth → pharynx → oesophagus → stomach
  • Mouth → pharynx → oesophagus takes approximately 1 second by skeletal muscle

The Act of Swallowing:

  • Tongue pushes food up against hard palate and food then rolls toward the back of the tongue
  • Bolus (food mixture) is forced into pharynx by skeletal muscle
  • Breathing stops briefly as soft palate lifts and closes airways to the nose
  • The larynx (voice box) lifts while the glottis (opening of vocal chords) closes
  • The epiglottis closes over the glottis
  • As these structures close the muscles of the pharynx contract and force the bolus down the oesophagus, over the epiglottis towards the stomach
  • Once the bolus is in the oesophagus, the upper oesophageal sphincter closes behind the bolus
  • The glottis opens and breathing starts again
  • Peristalsis pushes the bolus down the oesophagus until it reaches just before the stomach

It takes a solid/semi solid to pass from mouth → stomach is about 4 – 8 seconds. Liquid take about 1 second

If the lower oesophageal sphincter (tight circular muscle just prior to stomach) does not close the hydrochloric acid (HCl) can enter the oesophagus causing reflux. The oesophageal wall is burnt by the HCl resulting in heartburn.

Vascular Supply of the GIT

Arterial blood to the gut is via vessels branching from the abdominal aorta.

Venous blood leaves the gut carrying nutrients absorbed across the gut wall and is transported to the liver before returning to the right side of the heart. Called the Hepatic Portal Circulation. The blood enters the liver through the hepatic portal vein and leaves the liver through the hepatic veins, going to the inferior vena cava.


  • Large organ weighing approx 1.5kg
  • Divided into 4 lobes
  • The digestive function of the liver is to produce bile, which is a fat emulsifier.

Bile (emulsifies fats)

  • Mainly water, with bile salts, cholesterol, lecithin and some ions with bile salts involved with the emulsification of fats.
  • If there is not enough bile salts or lecithin, or too much cholesterol, or the gall bladder becomes inflamed then gallstones form.
  • A yellow-green, alkaline solution containing bile salts, bile pigments (primarily bilirubin), cholesterol, neutral fats, phospholipids, and a variety of electrolytes.


  • An exocrine and endocrine gland approx 12cm long and 2.5cm thick
  • Lies behind the stomach
  • Secretes a number of enzymes, bicarbonates and some salts which are all dissolved in water
  • Approx 1 – 1.5 L of pancreatic juice is secreted each day
  • Secretion of pancreatic juice is regulated by local hormones and the parasympathetic nervous system.


Pancreatic amylase

  • Breaks down starches (polysaccharides) to maltose (disaccharide).


  • Breaks down fats (triglycerides) already emulsified by the bile salts and converts them to fatty acids and monoglycerides.

Trypsin (produced in pancreas in an inactive form otherwise it would digest the pancreas)

  • Secreted as trypsinogen and activated by the enzyme enterokinase.
  • Converts proteins to peptides.

Chymotrypsin (produced in pancreas in an inactive form otherwise it would digest the pancreas)

  • Secreted as chymotrypsinogen and activated by trypsin.
  • Converts proteins to peptides.

Carboxyploypeptidase (produced in pancreas in an inactive form otherwise it would digest the pancreas)

  • Secreted as procarboxypolypeptidase and activated by trypsin.
  • Digests peptides to smaller peptides and amino acids


  • Convert substrates to pentoses and nitrogen bases
  • Produced by the pancreas and small intestine
  • Act on ribonucleic acid nucleotides


  • Convert substrates to pentoses and nitrogen bases
  • Produced by the pancreas and small intestine
  • Act on DNA nucleotides

Endocrine Pancreas

Islets of Langerhans contain 3 cell types:

  1. Alpha – secrete glucagon
  2. Beta – secrete insulin
  3. Delta – secrete Growth Hormone Inhibiting Factor (Somatostatin). Somatostatin inhibits the secretion of insulin and glucagon.

Glucagon – increases blood sugar by speeding up the conversion of glycogen (storage form of sugar) back to glucose and converting amino acids, glycerol and lactic acid to glucose (in the liver).

Insulin - opposite action to glucagon.  Decreases blood sugar by speeding up the transport of glucose into cells (particularly liver and skeletal muscle).  Also decreases glycogen breakdown and decreases the conversion of metabolites to glucose, stimulates conversion of glucose to fat and stimulated protein synthesis.



NSAID’s (Non-Steroidal Anti-Inflammatory Drugs)

  • Salicylates
  • Aspirin
  • Indoles
  • Indomethacin
  • Fenamates
  • Diclofenac
  • Cox 2 Inhibitors
  • Celecoxib

Adverse Effects: Loss of mucous lining in stomach → Gastritis


  • Osteoarthritis
  • RH Arthritis
  • Ankylosing spondylitis
  • Gout
  • Dental Pain
  • Acute and Chronic inflammation pain
  • Headache
  • Post op bone pain

Precautions: GI Bleeding/disorders, hypertension.

Interactions: Anti-hypertensive agents, diuretics, methotrexate, anti-coag’s, Lithium, Digoxin.

Must be taken with food.

The Heart

Tags: | | | | | | | | | | | | | | | | |

Heart Anatomy

Size, Location and Orientation

  • Size of a fist and weighs 250-300 grams
  • Found in the mediastinum and two-thirds lies left of the midsternal line
  • Base is directed toward the right shoulder and the apex points towards the left hip


  • Enclosed in a double-walled sac called the pericardium
  • Deep to the pericardium is the serous pericardium
  • The parietal pericardium lines the inside of the pericardium
  • The visceral pericardium (or epicardium), covers the surface of the heart

Layers of the Heart Wall

  • The myocardium is composed mainly of cardiac muscle
  • The endocardium lines the chambers of the heart


  • The right and left atria are the receiving chambers
  • The right ventricle pumps blood into the pulmonary trunk; the left ventricle pumps blood into the aorta

Blood Circuits

  • The right side of the heart pumps blood into the pulmonary circuit (heart→ lungs → heart).
  • The left side of the heart pumps blood into the systemic circuit (heart → rest of body → heart)

Heart Valves

  • The tricuspid and bicuspid valves prevent back-flow into the atria when the ventricles contract
  • When the heart is relaxed the AV valves are open and when the heart contracts the AV valves close
  • The aortic and pulmonary semilunar valves prevent back-flow of blood into the ventricles
  • When the heart is relaxed the semilunar valves are closed and when it contracts the semilunar valves are open

Cardiac Muscle Fibres

  • Striated
  • Cells are short, fat, branched and interconnected by intercalated discs
  • Contract as a whole unit or not at all

Heart Physiology

Electrical Events

  • Electrical impulses pass through the autorhythmic cardiac cells in the following order:
    • Sinoatrial node → atrioventricular node → atrioventricular bundle → right and left branches → Purkinje fibres
  • The autonomic nervous system modifies the heart beat
  • The sympathetic centre increases rate and depth of heart beat
  • The parasympathetic centre slows the heart beat

Heart Sounds

  • First heart sound – LUB – corresponds to the closure of the AV valves and occurs during ventricular systole
  • Second heart sound – DUP – corresponds to the closure of the semilunar valves and occurs during ventricular diastole
  • Heart murmurs are due to backflow of blood through a valve that does not close tightly
  • Systole is the contractile stage; diastole is the relaxation phase

Cardiac Output

  • Defined as the amount of blood pumped out of a ventricle per beat

Regulation of Heart Rate

  • Adrenaline, thyroxine and calcium influence heart rate
  • Age, gender, exercise and body temp all influence heart rate

Homeostatic Imbalance

  • Congestive heart failure occurs when the pumping efficiency of the heart is so low that blood circulation cannot meet tissue needs
  • Pulmonary congestion occurs when one side of the heart fails, resulting in pulmonary edema


  • Sclerosis and thickening of the valve flaps occur over time in response to constant pressure of the blood against the valve flaps
  • Atherosclerosis is the gradual deposit of fatty plaques in the walls of the systemic vessels

Blood Vessel Structure and Function

Blood Vessel Walls

The walls of all but the smallest blood vessels consist of 3 layers:

  1. Tunica interna
    • Reduces friction between the vessel walls and blood
  2. Tunica media
    • Controls vasoconstriction and vasodilation of the vessel
  3. Tunica externa
    • Protects, reinforces and anchors the vessel to surrounding structures

Arterial System

  • Elastic arteries contain large amounts of elastin which enables vessels to withstand and smooth out pressure fluctuations due to heart action
  • Arterioles are the smallest arteries and regulate blood flow into capillary beds through vasoconstriction and vasodilation
  • Capillaries are the smallest vessels and allow for exchange of substances between the blood and interstitial fluid


Blood Flow – the volume of blood flowing through a vessel, organ or entire circulation in a given period. Expressed as mL/min.

Blood Pressure - the force per unit area exerted by the blood against a vessel wall. Expressed as mmHg.

Resistance - a measure of friction between blood and the vessel wall. Arises from 3 sources:

  • Blood viscosity
  • Blood vessel length
  • Blood vessel diameter

If BP increases = blood flow increases.

If peripheral resistance increases = decreased blood flow


What causes fainting?

Tags: | |

Fainting usually happens when your blood pressure drops suddenly, causing a decrease in blood flow to your brain. This is more common in older people. Some causes of fainting include

  • Heat or dehydration
  • Emotional distress
  • Standing up too quickly
  • Certain medicines
  • Drop in blood sugar
  • Heart problems

Fainting is usually nothing to worry about, but it can sometimes be a sign of a serious problem. If you faint, it’s important to see your health care provider and find out why it happened.


Ref: http://www.nlm.nih.gov/medlineplus/fainting.html

Accessed 23/02/2012

Central Nervous System


The Central Nervous System (CNS) comprises the brain and the spinal cord.


The central cavity of the CNS consists of the ventricles of the brain and the central canal of the spinal cord. They are lined with ependymal cells and are filled with cerebrospinal fluid (CSF).

4 continuously connected ventricles are found within the brain:

  • The paired lateral ventricles lie deep within each cerebral hemisphere
  • The third ventricle lies within the diencephalon
  • The fourth ventricle lies in the hindbrain

The brain can be divided into 4 regions:


The cerebral hemispheres comprise about 83% of the brain mass and are characterised by ridges and grooves called gyri and sulci. The hemispheres are separated along the midline by the longitudinal fissure, and are separated from the cerebellum along the transverse cerebral fissure.

One hemisphere (usually the left) dominates language abilities, math and logic while  the other hemisphere (usually the right) dominates visual-spatial skills, intuition, emotion and artistic and musical skills.

The 5 lobes of the brain separated by specific sulci are:

  • Frontal lobe - responsible for voluntary somatic functions, olfaction, intellect, cognition, learning, memory and personality.
  • Parietal lobe – responsible for skin sensory and muscle sensory organ inputs.
  • Temporal lobe – responsible for auditory function and olfaction.
  • Occipital lobe – responsible for vision
  • Insula – responsible for vestibular function (balance) and visceral sensation

Each cerebral hemisphere has 3 regions:

  1. Cortex of grey matter
  2. Internal region of white matter
  3. and Islands of grey matter called basal nuclei deep within the white matter

Cerebral Cortex

  • Location of the conscious mind
  • Allows up to communicate, remember and understand
  • Comprises 40% of the brain mass and consists largely of grey matter

3 kinds of functional areas within the cerebral cortex:

  1. Motor areas – located in the frontal lobes, which control voluntary movement
  2. Sensory areas – in the parietal, temporal and occipital lobes. Concerned with conscious awareness of sensation
  3. Association areas – these communicate with motor and sensory areas to analyse and act on sensory inputs. Also responsible for intellect, cognition, recall and personality.

Cerebral White Matter – responsible for communication between cerebral areas and between the cerebral cortex and lower CNS centres.

Basal Nuclei (basal ganglia) – play a role in motor control and the regulation of attention and cognition.



A set of grey matter areas at the centre of the forebrain and consists of the:

  • Thalamus
    • Makes up 80% of the diencephalon.
    • Contains about a dozen nuclei and plays a role in mediation sensation, motor activities, cortical arousal, learning and memory.
  • Hypothalamus
    • Located below the thalamus
    • Control centre of the body
    • Regulates ANS activity eg. Emotional response, body temp, food intake, sleep-wake cycles and endocrine function
  • Epithalamus
    • Most dorsal position and includes the pineal gland which secretes melatonin and regulates the sleep-wake cycle



Consists of the midbrain, pons and medulla oblongata

  • Produces rigidly programmed, automatic behaviours necessary for survival
  • Midbrain
    • Contain large motor tracts descending toward the spinal cord
    • A number of nuclei are also embedded within the white matter
  • Pons
    • Contain fibre tracts that complete conduction pathways between the brain and spinal cord.
    • Controls breathing
  • Medulla Oblongata
    • Controls heart and respiratory rates
    • Controls vomiting, hiccupping, swallowing, coughing and sneezing



  • Comprises 11% of brain mass
  • Located dorsal to the pons and medulla
  • Processes inputs from several structures and co-ordinates skeletal muscle contraction to produce smooth movement
  • Cerebellar activity is unconscious



The Limbic System

  • Found in each cerebral hemisphere and the diencephalon
  • Involved with emotions
  • Causes emotional reactions to events


The Reticular Formation

  • Extends through the brain stem
  • Acts as a filter for sensory inputs we receive
  • Helps avoid sensory overload



The brain is protected by the skull, meninges, the cerebrospinal fluid and the blood-brain barrier.


  • 3 connective tissue membranes that cover and protect the CNS, protect blood vessels and enclose venous sinuses, contain cerebrospinal fluid and partition the brain.

Cerebrospinal Fluid (CSF)

  • Fluid found within the ventricles of the brain and surrounding the brain and spinal cord.
  • Gives buoyancy to the brain, protects the brain and spinal cord from impact damage
  • Delivers nutrients and chemical signals
  • Monitored by the medulla and hypothalamus

Blood-Brain Barrier

  • Protective mechanism that helps maintain a protective environment for the brain, by allowing only hormones and amino acids required by the brain to enter



Enclosed in the vertebral column and extend from the foramen magnum of the skull to either L1 or L2

  • Major reflex centre
  • 2-way conduction pathway
  • Protected by bone, meninges and CSF



Nerve Function

Tags: | | | | | | | | | | | | | | | | | | | | |


  • Typically about -70mV
  • Generated by differences between intracellular fluid (ICF) and extracellular fluid (ECF):
    • ICF has high K⁺ and low Na⁺
    • ECF has low K⁺ and high Na⁺
    • ICF anions mainly proteins
    • ECF anions mainly Cl⁻
    • Maintained by sodium-potassium pump
    • Ions enter and leave cells through ion channels:
      • Passive or leakage channels always open
      • Active or gated channels can be opened or closed
      • Chemically gated or ligand gated channels controlled by neurotransmitters
      • Voltage-gated channels respond to changes in membrane potential
      • Mechanically-gated channels respond to physical deformation



Used as communication signals. Can be:

  • Depolarisations, or
  • Hyperpolarisations

Graded potentials – local, short-lived changes in membrane potential. In a sensory neurone these are generator potentials.

Action potentials (AP) – (Nerve impulses)

Generation involves:

  • Transient increase in Na⁺ permeability
  • Restoration of Na⁺ impermeability
  • Short-lived increase in K⁺ permeability

Phases of an AP:

  • Resting phase – membrane potential maintained at ~-70mV
  • Depolarising phase – Na⁺ gates open causing depolarisation. This becomes runaway at the threshold level, producing spike AP
  • Repolarising phase - Na⁺ gates close and K⁺ gates open causing repolarisation.
  • Hyperpolarisation – Repolarisation overshoots. Sodium-potassium pumps then restore ionic balance.


  • Are all or none. Stimulus intensity is coded by AP frequency, not size.
  • Travel faster in large axons and myelinated axons

Refractory periods – during an AP, a neurone cannot respond to another stimulus.

  • Absolute refractory period
  • Relative refractory period



A junction between 2 neurones or a neurone and an effector. 2 Types:

  1. Electrical synapses – direct cell-cell contact via ion channels
  2. Chemical Synapses – communication involves neurotransmitters. Synapse comprises:
    1. Axon terminal knob – containing synaptic vesicles
    2. Synaptic cleft – fluid-filled space between cells
    3. Postsynaptic membrane – containing neurotransmitter receptors

Events at the Synapse

  • Depolarisation causes Ca²⁺ to enter the cell
  • High Ca²⁺ causes synaptic vesicles to release neurotransmitter
  • Neurotransmitter binds to protein receptors in post-synaptic membrane
  • Ion channels open, causing change in membrane potential
  • Neurotransmitter is removed
  • Slow process – synaptic delay

Post-synaptic potentials

  • Excitatory (EPSP):
    • Causes depolarisation
    • Generate an EPSP which helps trigger an AP in the post-synaptic cell.
  • Inhibitory (IPSP):
    • Causes hyperpolarisation
    • Generate an IPSP which helps prevent a AP in the port-synaptic cell.



  • Acetylcholine (Ach) – neurotransmitter junctions, preganglionic fibres of the ANS and parasympathetic postganglionic fibres.
  • Noradrenaline – postganglionic fibres of the sympathetic division of the ANS



Major Endocrine Organs

Tags: | | | | | | | | | | | | | | | | |



  • Located at the base of the brain – below the hypothalamus
  • Sometimes called “the master” gland
  • Pea shaped with 2 lobes and a stalk
  • Has 2 lobes:
    • Posterior Pituitary
      • Consists of nerve tissue with direct nerve connections to the hypothalamus
      • 2 polypeptide neurohormones are synthesised by the hypothalamus:
        • Oxytocin
          • acts on smooth muscle of the uterus and breast to cause uterine contractions during childbirth and milk let-down during nursing.
        • Antidiuretic hormone (ADH)
          • acts on kidney tubules to promote increased water reabsorption
          • at high concentrations it causes vasoconstriction and high blood pressure (called a vasopressin)
          • ensures the body does not excrete too much fluid
    • Anterior Pituitary
      • The hypothalamus controls the anterior pituitary by means of releasing and inhibiting hormones sent through the hypophyseal portal system.
      • There are 6 anterior pituitary hormones:
        • Growth hormone (GH)
          • stimulates cell division
        • Thyroid Stimulating Hormone (TSH)
          • stimulates normal development and secretion of the thyroid gland
        • Adrenocorticotrophic Hormone (ACTH)
          • stimulates the adrenal cortex to release corticosteroid hormones
          • helps the body to resist stress
        • Follicle Stimulating Hormone (FSH)
          • stimulates sperm and egg cell production
        • Leuteinizing Hormone (LH)
          • promotes ovulation in females and production of gonadal hormones
        • Prolactin
          • stimulates milk production



  • Located in the brain
  • Helps regulate the body’s internal environment
  • Helps control heart rate, temperature, water balance and controls the pituitary gland



  • Located on the trachea just below the larynx
  • thyroid hormone acts on all body cells to increase basal metabolic rate and body heat production
  • Calcitonin hormone lowers blood calcium by inhibiting osteoclast activity and stimulating Ca ²+ uptake – decreases rate of bone breakdown



  • Located on the surface of the thyroid glands
  • Contain chief cells that secrete parathyroid hormone – which increases blood Ca²+ levels
  • Increases Vit D synthesis
  • Maintains normal calcium levels


  • Located on top of the kidneys
  • 2 separate glands
    • Adrenal Medulla
      • located at the centre of the adrenal gland
      • derived of nerve tissue and is under nervous control – sympathetic NS
      • secretes adrenaline and noradrenaline (fight or flight response)
      • increases or decreases heart rate and pressure
    • Adrenal Cortex
      • outer layers of the adrenal gland
      • its hormones are steroids aka corticosteroids – and are synthesised from cholesterol
      • steroid groups:
        • Mineralocorticoids – mostly aldosterone – are essential for electrolyte balance of extracellular fluids.
        • Glucocorticoids – are released in response to stress and inflammation through the action of ACTH
        • Gonadocorticoids – weak androgens which are converted to testosterone and oestrogens in the tissue cells.



  • Both insulin and glucagon hormones involved in blood glucose level regulation
  • Insulin – lowers blood sugar levels by enhancing membrane transport of glucose into body cells
  • Glucagon – targets the liver where it releases glucose to the blood = increased blood sugar levels (BSL)
  • Composed of both endocrine and exocrine gland cells
  • The islets of Langerhans produce pancreatic hormones



  • Testes and ovaries produce the steroid hormones testosterone, oestrogens and progesterone – which its release is controlled by FSH and LH
  • Involved in the development of reproductive organs, gamete production and regulation of sexual cycles



  • Maintains melatonin in blood



  • Important for the normal development of lymphocytes (T cells) – important for immune response




Tags: | | | | | | | | | | | | | |

Tissue – many cells similar in structure and function.

4 Types:

  1. Epithelial
    1. Tissue which forms the surface of a structure
    2. Covering Epithelia
      1. Closely packed cells with no intercellular spaces
      2. Outer surface free; inner surface bounded by basement membrane
      3. Defined by cell type and cell layers:
        1. Cell types:  squamous (flat),  cuboidal (cube-shaped),  columnar (longer than they are broad)
        2. Cell layers: simple (cells same height), pseudostratified (one layer, different heights) or stratified (in several different layers)
    3. Glandular Epithelia
      1. Tissue producing a secretion
      2. Exocrine glands: secretion to a body surface eg. sweat glands
      3. Endocrine glands: secretion into the blood eg. thyroid gland
  2. Connective
    1. Cells widely spaced and embedded in a non-cellular matrix
    2. Ordinary Connective Tissue
      1. Areolar tissue:  matirx soft, fibres arranged as loose network eg. adipose tissue
      2. Dense fibrous tissue:  fibres predominate eg. tendons, ligaments, dermis
      3. Function – holding many body parts together and some of the cells protect the body from infections.
    3. Skeletal Connective Tissue
      1. Cartilage:  Matrix semi-solid & flexible, cells in fluid-filled spaces
        1. Found where strength and flexibility are needed eg. pinna of the ear and trachea.
        2. Covers bone at movable joints making surface smooth to reduce friction.
      2. Bone:  Matrix solid and rigid
        1. Give the body shape and support
        2. Acts as levers for movement and form protective casing for delicate structures (eg. brain)
    4. Blood & Lymphatic Connective Tissue
      1. Haemopoietic tissue:  Lymphoid tissue in spleen, thymus and lymph nodes.
      2. Blood & Lymph:  Cells in a liquid matrix of colloidal proteins and solutes.
  3. Muscular
    1. Contractile cells (muscle fibres) bound as sheets or bundles. 3 types:
      1. Skeletal Muscle
        1. Generally attached to bone
        2. Under voluntary control
        3. Strongly striated
        4. Cells long, tapering and multinucleate
      2. Cardiac Muscle
        1. Forms the myocardium of the heart
        2. Under autonomic control
        3. Visible striations
        4. Cells elongated, branches and one nucleus
        5. Intercalated discs at cell junctions
      3. Smooth Muscle
        1. Found in internal organs
        2. Under autonomic control
        3. No visible striations
        4. Cells spindle-shaped, arranged in sheets
        5. One cell nucleus
  4. Nervous
    1. Allows rapid communication within the body
    2. Makes up the brain, spinal cord, peripheral nerves and ganglia
    3. Includes neurones, neuroglia and supporting cells eg. Schwann Cells


Organ: A structure within a differentiated role in the body and containing different tissues. The largest organ is the skin

Organ System:  A collection of organs working together for a particular purpose.

Organism:  A collection of organ systems capable of maintaining itself indefinately.


[ © 2007 - 2016 | my:WorldConfusion.com (www.worldconfusion.com) ]