Nerve impulse conduction at synapse

 

Synapse is junction between two Cell in which one cell is neuron and another cell may be nerve, muscle or gland.

In Cardiac muscle, Junction between muscle and muscle is synapse.The neuron Sending the signal is called presynaptic neuron while neuron receiving the message is Called post synaptic neuron.

synapse may be;

• Axodendritic: From axon to dendrite.

• Axosomatic: From axon to Cell body.

• Axoaxonic: From axon to axon.

The pre-synaptic cell is generally a neuron while postsynaptic  cell may be neuron, muscle or gland.

The synapses are essential for homeostasis because they allow information to be filtered and integrated. During learning, the structure and function of a synapse Changes new synapses are formed and previous synapses are destroyed.

synapse are of two types;  Chemical synapse and electrical synapse.

Nerve impulse: Generation and conduction

 

Nerve impulse Conduction:

The propagation of action potential in nerve is called nerve impulse Conduction. The nerve Impulse (electrical impulses) propagates in the form of wave of depolarisation and repolarisation.

The cell membrane of neuron (nerve Cell) consists of pump and Channels. They are:

 

• Na-k pump: also called Na-k ATPase. It is an enzyme that moves sodium and potassium ions across Cell membrane. This pump uses energy from ATP to move 3 sodium ions out of Cell and two potassium ions into the Cell. This helps to maintain concentration gradient of sodium and potassium across cell membrane. This gradient helps to generate resting membrane potential. @ NOKIA

Human Nervous System: Brain

 Brain: It is central processing unit of body and acts as command and Control system of body. It regulates all processes of body.

process of formation of brain: It is formed from neural tube and the neural crests make Peripheral nervous system. the spinal Cord is also formed from posterior part of neural tube.

Human Arterial System

 

 Human Arterial system :

consists of two main arteries :

1. pulmonary artery and

2. Aorta

pulmonary artery :

Arises from top Left  region of Rt. ventricle and divides into two branches : Rt. pulmonary artery and Lt. pulmonany artery. Rt- Pulmonary artery Carry deoxygenated blood to Rt lungs. Lt. pulmonary artery Carry deoxygenated blood to Lt lungs.

Human Excretory System: Urine and Micturition

 Urine and micturition

urine is liquid and Consists of 96% - water, 2 % urea, 2% other substances. Other substances includes organic and inorganic Substances like Uric acid, creatinine, Hippuric acid, Na, K, Ca, Mg, Chloride etc.

About 1.5 to 2  ltrs urine is formed each day. It is transparent light yellow coloured due to pigment urochrome.

Human Excretory System : Counter current Mechanism

 

Counter Current Mechanism

The countercurrent mechanism is a  process that occurs in the kidneys, enabling them to concentrate urine and maintain water and electrolyte balance in the body. It primarily takes place in the loop of Henle, and involves the countercurrent multiplier system in the loop of Henle and the countercurrent exchanger in the vasa  recta (the parallel network of capillaries around LOH).

Human Excretory System: Mechanism of urine formation

 

Mechanism of urine formation or Process of urine formation:

The process of formation of   Urine is called Uropoiesis. It takes place in nephron. Each nephron is independent and Can Produce miniscule amount of urine. This process gets completed in 3 steps; Ultrafiltration, selective reabsorption and tubular secretion.

• Ultrafiltration: It is process in which blood is filtered under pressure in malphigian body of nephron.

The main driving pressure for it is hydrostatic pressure of blood in glomerulus (A) which is about (60-70) mmHg. However, this pressure is opposed by osmotic pressure of plasma protein or Blood Colloidal osmotic pressure (B) which is about 30mmHg and also opposed by capsular hydrostatic pressure or hydrostatic pressure of nephric filtrate in Cavity of Bowmans Capsule (C) which is about 20 mmHg.