B5
- Created by: doowaD
- Created on: 03-11-17 17:12
View mindmap
- B5
- Homeostasis
- Homeostasis is the maintenance of a constant internal environment in response to external conditions. The nervous system and hormones are responsible for this.
- The body has a lot of control systems that keep the conditions in your body steady. These control systems are automatic. They control conditions through three main parts.
- Receptors, Coordination Centres, Effectors
- How a Control System Works: A receptor detects a stimuli(A change in the environment). It sends information to the coordination centre. The coordination centre recieves and processes the information. It then organises a response. An effector produces a response.
- The Nervous System
- The nervous system reacts to stimuli and coordinate the behaviour. The nervous system is mad up of different parts.
- Central Nervous System (CNS): This consists of the brain and spinal cord. The CNS is connected to the body by sensory neurones and motor neurones.
- The CNS is a coordination centre. It receives information from the receptors and then coordinates a response. The response is carried out by effectors.
- Stimulus Receptor--Sensory Neurone--CNS-- Motor Neurone-- Effector--Response.
- The CNS is a coordination centre. It receives information from the receptors and then coordinates a response. The response is carried out by effectors.
- Receptors: Receptors are the cells that detect stimuli. Different receptors detect different stimuli. For example, receptors in the ears detect sound.
- Motor Neurone: These carry electrical impulses from the CNS to effectors.
- Effectors: Effectors respond to electrical impulses and bring about a change. Muscles and glands are effectors. They respond in different ways-muscles contract and glands release hormones.
- Central Nervous System (CNS): This consists of the brain and spinal cord. The CNS is connected to the body by sensory neurones and motor neurones.
- The nervous system reacts to stimuli and coordinate the behaviour. The nervous system is mad up of different parts.
- Synapses & Reflexes
- Information is passed between neurones really quickly, especially when there is a reflex involved.
- A synapse is a structure that permits a neuron to pass an electrical or chemical signal to another neuron. The electrical impulse is passed from one neurone to the next by chemicals. These chemicals move across the gap. The chemicals start off a new electrical impulse in the next neurone.
- Reflexes are automatic responses-you don't have to think about them. This makes them really quick. They can help you from getting injured. The passage of information in a reflex is called a reflex arc. The neurons in reflex arcs go through the spinal cord or through an unconscious part of the brain.
- Here's what would happen if you got stung by a bee: 1) Cheeky bee stings your finger. Bee sting is detected by receptors. 2) Impulses are sent along a sensory neurone to the CNS. 3) In the CNS , a relay neurone passes on the impulses from the sensory neurone to a motor neurone. 4) Impulses are sent along the motor neurone to the effector. 5) The effector here is a muscle. It contracts to move your hand away from the bee.
- Information is passed between neurones really quickly, especially when there is a reflex involved.
- The Endocrine System
- Hormones are chemicals released by glands. They're released directly into the blood. These glands are carried in the blood to other parts of the body. They only effect particular cells in particular organs.(Target Organs)
- Hormones & Nerves have differences. Nerves: Very fast reaction. Act for a very short time. Act on a very precise area. Hormones: Slower reaction. Act for a long time. Act in a more general way.;
- Examples of Glands: The Pituitary Gland:sometimes called the master gland. This is because it produces many of the hormones that regulate body conditions. These hormones act on other glands. They make the glands release hormones that bring about change.
- Ovaries:-Females Only- These produce oestrogen which is involved with the menstrual cycle .
- The Pancreas: Produces insulin which is used to regulate blood and glucose level.
- Hormones are chemicals released by glands. They're released directly into the blood. These glands are carried in the blood to other parts of the body. They only effect particular cells in particular organs.(Target Organs)
- Controlling Blood Glucose
- Eating carbohydrates puts glucose into the blood. Glucose is removed from the blood by cells. When you exercise, a lot more glucose is removed from the blood. Changes in the blood concentration are monitored by the pancreas. If blood glucose concentration gets too high the pancreas releases the hormone insulin. Insulin causes glucose to move into cells. Glucose can be stored as glycogen. Glucose is converted to glycogen in liver and muscle cells.
- Diabetes: With diabetes you cant control your blood sugar. There are two types.
- Type 1: This is were the pancreas produces little or no insulin. This means a person's blood sugar level can rise to a level that can kill them. People with type one diabetes need insulin injections throughout the day. This makes sure that glucose is removed from the blood quickly after the food is digested.
- Type 2: This is where a person becomes resistant to their own insulin. This means they still produce insulin, but there body's cells don't respond properly to it. This can cause a person's blood sugar level to rise to a dangerous level. Being obese can increase you chance of developing type 2 diabetes. It is controlled by eating a carbohydrate-controlled diet. It can also be controlled by taking regular exercise.
- Puberty & Menstrual Cycle:
- At puberty your body starts releasing sex hormones. These sex hormones trigger secondary sexual characteristics. For example, the development of facial hair in men and breasts in women. Female sex hormones also cause eggs to mature in women, In men, the main reproductive system hormone is testosterone. It's produced by the testes. It stimulates sperm production. In women, the main reproductive hormone is oestrogen. It's produced by the ovaries. Oestrogen is used in involved in the menstrual cycle.
- The Menstrual cycle has four stages.
- Stage 1: Day 1 is when menstruation starts. The uterus lining breaks down for about four days. Stage 2: the uterus lining builds back up again from day 4-14. It builds into a thick spongy layer full of blood vessels. Stage 3: An egg develops and is released from the ovary at day 14. This is called ovulation. Stage 4: They wall is then maintained for about 14 days until day 28, the spongy lining starts to break down. The whole cycle begins again.
- The Menstrual Cycle is controlled by four hormones.
- FSH(Follicle-Stimulating Hormone): Causes an egg to mature in one of the ovaries.
- LH(Lutenising Hormone): Causes the release of the egg(ovulation).
- Oestrogen & Progesterone: These hormones are involved in the growth and maintenance of the uterus lining.
- Controlling Fertility
- Fertility is how easy it is for a women to get pregnant. Contraceptives are things that prevent pregnancy. Hormones can be used in contraceptives-these are called hormonal contraceptives.
- Oral Contraceptives: Oral contraceptives are taken through the mouth as pills. They stop the hormone FSH from being released. They stop eggs maturing. Oral contraceptives are over 99% effective at preventing pregnancy. But they can have bad side effects. For example, they can cause headaches and make you feel sick.
- Some hormonal contraceptives work by slowly releasing progesterone which stops the egg from maturing or being released from the ovaries. Some examples are, Contraceptive patch, contraceptive implant and contraceptive injection.
- An intrauterine device (IUD) is a T-shaped device that is inserted into the uterus. It can stop fertilised eggs from implanting in the uterus wall. Some types of IUD release a hormone.
- Barrier Methods: Non hormonal contraceptives stop the sperm from getting to the egg. Barrier methods are one type of non-hormonal contraceptive. For example: Condoms, Female condoms. They are the only form of contraceptives that will protect against STD's. A Diaphragm is a shallow plastic cup that fits over the entrance to the uterus. It has to be used with spermicide.
- Homeostasis
- More drastic ways to stop pregnancy
- Sterilisation: Sterilisation in females involves cutting or tying the Fallopian tubes. In males it involves cutting or tying the sperm ducts. Sterilisation is permanent.
- Avoiding sexual intercourse when a women is at the stage of the menstrual cycle where she is most likely to get pregnant.
- Abstinence: The only way to be sure that sperm doesn't meet egg is to not have intercourse. This is called abstinence.
- Barrier Methods: Non hormonal contraceptives stop the sperm from getting to the egg. Barrier methods are one type of non-hormonal contraceptive. For example: Condoms, Female condoms. They are the only form of contraceptives that will protect against STD's. A Diaphragm is a shallow plastic cup that fits over the entrance to the uterus. It has to be used with spermicide.
Comments
No comments have yet been made