(I)GCSE Topic 2.85

Describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object

Receptor: Heat sensor in the skin
- The impulse travels to the spinal cord along the sensory nerve.
- In the spinal cord the impulse is passes on to the relay nerve.
- This passes the impulse on to the MOTOR NERVE. 

Effector: Arm muscles
- The motor nerve carries the impulse to the muscle in the arm.

Response: Muscles 

- Contract to remove the hand from the hot surface.  

(I)GCSE Topic 2.84

Understand that Stimulation of Receptors in the sense organs sends electrical impulses along nerves into and out of the Central Nervous System(CNS), resulting in rapid responses.

- Nervous system sends electrical messages along nerves to and from different parts of your body and they tell your body what to do.

- Sense Organs act as Receptors to detect change. They send messages to the CNS along the sensory nerves. 

- Nerve cels are different from other cells. They both have cell membranes; cytoplasms and nucleus but they are of a different shape. 

- Part of the cell is stretched out to form the AXON which can be over a metre long. 

- The messages that nerves carry are called NERVE IMPULSES which are electrical signals that pass very quickly along the axon of the nerves. 

- 

(I)GCSE Topic 2.83

Recall that the Central Nervous System consists of the Brain and Spinal Cord and is linked to sense organs by nerves.

- The main parts of the Nervous System consist of the Brain and Spinal Cord; forming the Central Nervous System (CNS). 

- Both are made of delicate nervous tissues. 

- The Brain is protected by the skull. 

- The Spinal Cord is protected by you back bone. 

- The CNS is connected to difference parts of the body by nerves; each nerve is made up of lots of Nerve Cells/ Neurons. 

(I)GCSE Topic 2.82

How responses can be controlled by Nervous or by Hormonal Communication and the differences between the two systems

The Nervous System 

- Controls your actions and co-ordinates the different parts of your body so that they are able to bring around the correct responses. 

- Co-ordinates our muscles so we able to do things such as blink, breath, or swallow. 

The Hormonal System 

- Chemicals produced by glands in the body and are carried around by the blood.

- They also tell the body how to respond. 

Differences

- Nervous System passes along information as electrical impulses. 

- Hormonal System passes information as chemical messengers in the blood.

- Nervous System effects are rapid and short-lived. 

- Hormonal System effects are usually slow and long-lasting. 

- Nervous System effects particular organs. 

- Hormonal Systems effects the whole of the body.

- Nervous Systems often involve reflexes. 

- Hormonal Systems involve the control of growth, development, metabolism and reproduction.

(I)GCSE 2.77 c) Osmoregulation

- Regulation of body water content = Homeostasis

 - Homeostasis is maintaining constant conditions

- Regulation is of body water content, largely making up Plasma and Tissue Fluids

- Homeostasis of water body content = OSMOREGULATION

- Major receptor in water body content = hypothalamus of the brain

- Stimulus to Hypothalamus = blood

- Effector = kidney

- Output of kidney = filtered blood

(I)GCSE 2.77 b) Thermoregulation

- Negative feedback loop = control and maintaining constant conditions

- Co-ordinator = body temp of 37 - 38 d.c.

- Receptor of body temperature = Hypothalamus of the brain

- Hypothalamus responds to temperature of the body/ blood

- Change in temperature brought about by receptor = skin

- Response = increase/ decrease in body temperature

(I)GCSE 2.76 Sensitivity

- Organisms are able to respond to changes in the environment. 

- MRS. NERG S = Sensitivity

- Sensitivity = characteristic when organisms respond to changes in the environment.

Types of changes in the environment: 

: light level 

: temperature 

: pressure level 

:chemicals 

- Organisms are required to have receptors in order to detect the changes.

- Organisms have effecters such as muscles or glands to respond.

- Response show that organisms are able to survive the changes in the environment. 

(I)GCSE 2.69 Urinary System

- Each kidney (left and right) would have its own blood supply carrying out the process of excretion and flitration. 

- Ureter = tube carrying the urine from the kidney to the bladder.

- Urine is excreted through the Urethra down through the vagina or penis. 

(I)GCSE 2.68 b) Osmoregulation

How the kidney carries out its roles of Osmoregulation

- The tissue layers surrounding each cell must be isotonic with the cytoplasm of the cells. This means that the amount of water going into and out of the cell is equal and the cells will remain the same size shape and function. 

- The danger to the tissue is the blood circulating into the tissue would be concentrated - causing a hypertonic tissue fluid. 

- It could also be very dilute causing a hypotonic tissue fluid.

- Both hypertonic and hypotonic tissue fluids are undesirable - Hypertonic removes too much water

                                                                                         - Hypotonic adds too much water

- The tissue fluid is Isotonic to the cell cytoplasm by controlling the composition of blood - blood controls the tissue fluid. 

- It is the job of the kidney to control the composition of our blood.

By controlling the content of water and salts in the blood, the kidney can keep the blood and therefore the tissue fluid Isotonic with the cells cytoplasm, maintaining the function of the cells. 

(I)GCSE 2.68 a) Excretion

How kidneys carry out its roles of excretion and osmoregulation.

- Urea contains Nitrogen which is toxic to the body and cannot be stored. 

- The original form of Nitrogen circulating in our blood stream are the Amino Acids.

- Amino acids are normally used for growth but extra amino acids must be removed - TOXIC this is the rule of both the liver and the kidneys. 

1. Blood circulates to the liver and the amino acid is broken down into molecules called the Urea. 

2. It then circulates to both of the kidneys. 

3. The kidneys will then filter the Urea from the bottom and the Urea will be added with water to form Urine. 

4. Urine will drain down the orators to collect down in the bladder.

5. Urea is now in the bladder in the form of Urine - it is removed from the body.

6. The filtered blood returns to the circulation with the toxic amino acids and urea removed. 

This is an example of excretion.  

(I)GCSE 2.67 b) Human Organs of Excretion

- Lungs, kidneys, and skin are organs of excretion. 

- Lungs excrete Carbon-dioxide

- Kidneys excrete Excess Water; Molecule Urea - hydrogen waste from amino acids; Salts 

- Skin excretes Water and Salts through sweat; Urea

(I)GCSE 2.67 a) Excretion in Plants

- PHOTOSYNTHESIS involves leaf absorbing light energy

- In this process, it combines CO2 and H2O to form a molecule such as C6H12O6(glucose) whilst giving off the gas O2

- The O2 gas is actually a wasted gas so this is an example of excretion = The release of Metabolic Waste.

- RESPIRATION 

- C6H12O6 + O2 (through a series of enzyme reactions, the glucose molecule is broken down) ATP(what is produced in the process) + CO2 + H2O

Plants excrete CO2 and O2 depending on whether they are doing Photosynthesis or Respiration.

(I)GCSE 3.34 Causes of Mutation

(I)GCSE 3.33 Antibiotic Resistance

(I)GCSE 3.32 Types of Mutation

(I)GCSE 3.31 Sexual and Asexual Reproduction

(I)GCSE 3.30 Mutation

(I)GCSE 3.29 Species Variation

(I)GCSE Topic 3.12 Amniotic Fluid

*The developing Embryo is protected by the Amniotic Fluid*

- Protection of the developing Embryo comes from comes from the fact that the fluid (largely water) cannot be compressed.

- Fluid Absorbs the pressure - prevent damage to the unborn child. 

(I)GCSE Male and Female

Primary -> Secondary FEMALE    

Begin to develop at the age of 13/14

Hips Widen 

Weight / Fat 

Facial Structure 

Breast 

Height

Period 

Body Hair 

Primary -> Secondary MALE    

Begin to develop at the age of 14/15

Voice

Facial Hair 

Weight 

Chest Hair 

Bone Widen / Grow 

Increase in Muscle