Human Organ System Basics Notes-According to 8th Class AKUEB Slos

Human Nervous System

4.1.1 Recognize the basic components of the nervous system and describe their function. U

The nervous system consists of two main parts:        

 1.The central nervous system                                        

2.Peripheral nervous system:                                                                           The central nervous system is made up of the brain and spinal cord. The peripheral nervous system is made up of the nerve fibers that branch off from the spinal cord and extend to all parts of the body.

Brain: Receiving information from the rest of the body, interpreting that information, and then guiding the body's response to it.

Also helps perform vital operations such as breathing, maintaining blood pressure, and releasing hormones.

Spinal Cord: Transmission of neural signals between the brain and the rest of the body.

Nerves : A bundle of fibers that uses electrical and chemical signals to transmit sensory and motor information from one body part to another.

4.1.2 Describe the function of different types of nerves. U

Sensory Nerves: Sensory neurons are nerve cells that transmit sensory information (sight, sound, feeling, etc.). Conduct sensory information (nerve impulse) from receptor towards CNS. They have one dendrite and one axon

Motor Nerves: Carry information from the CNS towards the EFFECTORS (Muscles or Glands). They have many dendrites but no only one axon.

Interneuron: These form Brain and Spinal Cord. They receive information, interpret them and stimulate motor neurons. They have many dendrites and axons.

4.2.1 Differentiate between voluntary and involuntary actions. U

4.2.2 Categorize different actions as voluntary and involuntary actions. U                                                                                                                     

Voluntary Action	Involuntary Action
An action that is done by your wish or happens with your permission	An action that happens itself and you can not control it
You can stop it or start it when required and is completely controlled by yourself	You can neither start it by yourself nor you can stop it by yourself
These include Reading, writing, cycling, swimming, fighting, talking, walking, running.	These include Breathing, respiration, heart beat, circulation of blood, excretion, digestion

4.2.3 Justify reflex action as an involuntary action U

Reflex action is a quick response to a stimulus and it does not involve the higher centers of brain, such responses are not under conscious control and are called involuntary actions.

An example of reflex action is : When your hand touches a hot cup of tea, you move away the hand suddenly and that action without your control is reflex action or involuntary action

4.3.1 Explain the different modes of excretion i.e through lungs, skin and kidneys U

Through lungs: Our cells produce Carbon dioxide as a waste product of respiration and this carbon dioxide is harmful for us. From cells, carbondioxide diffuse into tissue fluid and then blood carries this carbon dioxide to the lungs, which excrete it out in exhalation

Through Skin: It helps in the excretion of heat, water, and salts. Dead cells constantly flake off and living cells directly below make the top layer. Excess body heat is released by evaporation and sweat, which in result provide cooling effect to the body

Through Kidney :  The kidneys excrete a variety of waste products produced by metabolism. These include the nitrogenous wastes called "urea", from protein catabolism, as well asuric acid, from nucleic acid metabolism. Formation of urine is also the function of the kidney

4.3.2 Recognize the basic components of excretory system and describe their function U

Kidneys:  The kidneys are the waste filtering and disposal system of the body

Ureters: Ureters are muscular ducts that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually 25–30 cm (10–12 in) long.

Bladder: The urinary bladder is the organ that collects urine excreted by the kidneys prior to disposal by urination. It is a hollow muscular and elastic organ, and sits on the pelvic floor. Urine enters the bladder via the ureters and exits via the urethra.

Urethra: A tube that carries urine from the bladder to the outside of the body.

4.3.3. Describe the structure of kidney U

>Kidneys are dark-red, bean shaped organs. Each kidney is 10 cm long, 5 cm wide and 4 cm thick and weighs about 120 grams.

 >They are placed against the back wall of abdominal cavity just below diaphragm, one on either side of vertebral column. They are protected by the last 2 ribs. The left kidney is a little higher than the right.

>The concave side of kidney faces vertebral column. There is a depression, called hilus, near the centre of the concave area of kidney. This is the area of kidney through which ureter leaves kidney and other structures including blood vessels, lymphatic vessels and nerves enter and leave kidney.

Kidney has two regions

> Renal cortex is the outer part of kidney and it is dark red in colour.

>Renal medulla is the inner part of kidney and is pale red in colour. Renal medulla consists of several cone shaped areas called renal pyramids.

 >Renal pyramids project into a funnel-shaped cavity called renal pelvis, which is the base of ureter.

4.3.4 Outline the role of kidney in excretion of wastes U

The kidneys control the amount of liquid in our bodies. Wastes are called urine and include urea, water and inorganic salts. The cleansed blood goes into veins that carry the blood from the kidneys and back to the heart. And the waste in form of urine is excreted out from the body

4.3.5 Identify the possible causes of malfunctioning of kidneys  K

Diet  (containing more green vegetables, salts, vitamins C and D)

Urinary tract infections

Less intake of water 

Alcohol consumption

Diabetes mellitus

Hypertension