Homeostatis and Response

• dendrites collect impulses from receptor cells
• axons pass through impulses to other neurons
• features and adaptions that neurons have?

  neurons have a fatty myelin sheath -> so it can insulate the neuron and so the electrical impulse cannot cross the myelin sheath to travel to neighbouring neurons they have lots of dendrites -> so they can communicate with other impulses

  long axon -> so they can carry nerve impulses in long distances to other parts of the body
• flow diagram of how the nervous system works?

  stimulus -> receptor -> central nervous system -> effector -> response
• reflex actions help avoid danger and harm and they control basic functions such as breathing
• reflex actions are automatic and rapid and they don't involve the conscious part of the brain
• the nervous system enables humans to react to their surroundings and to coordinate their behaviour
• (process) how do nerve impulses get transmitted from one neurone to the next?

  • when an electrical impulse arrives at the end of the membrane of the presynaptic neuron, the chemical messenger (neurotransmitter) is released into the synapse
• neurones do not touch each other, so there is a tiny gap called the synapse
• • nerve impulses cannot cross synapses, so the info is passed from 1 neuron to the next using chemical messengers (neurotransmitters) and through the process of diffusion - advantages is that it works in one direction and it allows 1 nerve impulse to produce impulses in several other neurons -disadvantages is that its slower than nerve impulses
• receptors are found in the sense organs (e.g tongue, eyes,skin) and they stimulate electrical charges in response to the change in environment
• what are the components in a control system?

  receptor , coordination centre (brain and spinal cord and pancreas) and effector (muscles and glands)
• Homeostatis uses automatic control systems involving nervous responses ( nervous system ) and chemical responses (endocrine system)
• what 3 things in the body are controlled by homeostatis?

  body temperature, glucose concentration and water levels
• Homeostatis also relies on a system of negative feedback where if the level of something rises, control systems reduce it again and vice versa (e.g body temperature)
• the menstrual cycle (process) ?

  Day 1 is when bleeding starts - where the lining of the uterus (womb) begins to break down which takes around 4-5 days Day 4 -14 is when the womb begins to thicken - once completed its ready to recieve a fertilised egg Day 14 is ovulation - where the egg is released from the ovary Day 14-28 is when the wall of the uterus is maintained for 14 days until day 28 - there is 2 options that could potentially occur in this stage
• What are the 2 options during the last stage of the menstrual cycle?

  -if a fertilised egg is recieved = pregnancy will continue - if no egg is recieved = the lining will break down and the cycle begins again
• what are the 4 hormones involved in the reproductive system ?

  FSH (follicle stimulating hormone) , Oestrogen , LH (luteinising hormone) and Progesterone
• What does the hormone FSH do? Where is it located?

  FSH causes maturation (development ) of an egg in the ovary, it also stimulates the production of oestrogen and its produced in the pituitary glands
• what does the hormone oestrogen do? where is it produced?

  Oestrogen causes the lining of the uterus to thicken and grow, it stimulates the production of LH and inhibits (slows down) the production of FSH , its the main female reproductive hormone thats produced in the ovary
• what does the hormone LH do? where is it produced?

  Luteinising Hormone stimulates ovulation at Day 14, its also stimulates the production of testerone and inhibits the production of progesterone, its produced at the pituitary glands
• what does the hormone progesterone do?

  progesterone maintains the lining of the uterus and inhibits the production of LH, when the progesterone levels fall - the lining breaks down and its produced at the ovaries
• Oral Contraceptive / Contraceptive Pill - advantages and disadvantages?

  Advantages: 99% Effective in preventing pregnancy if used correctly , easy to use, can regulate menstrual cycles and cramps Disadvantages: Can have side effects such as nausea, weight gain, , Requires daily use and may not protect against sexually transmitted infections.
• male condom - advantages and disadvantages?

  Advantages: Protection against sexually transmitted infections (STIs) , 98% effective if used correctly and its cheap Disadvantages: Can slip off, break or split
• female condom advantages and disadvantages?

  Advantages: Protection against STIs, can be inserted before sex Disadvantages: not as effective as male condoms (80%), single use
• diaphragms - advantages and disadvantages?

  Advantages: reusable, 92-96% effective with correct use and can insert before sex Disadvantages: spermicide only works for a certain amount of time
• implant - advantages and disadvantages?

  Advantages: 99% effective with correct use and lasts for 3 years Disadvantages: only removed by medical professional
• IUD - advantages and disadvantages?

  Advantages: 99% effective , last for up to 10 years Disadvantages: only inserted by medical professional and more painful periods
• injection - advantages and disadvantages?

  advantages : 99% effective with correct use , lasts for 8-12 week timeframe disadvantages : cannot remove from the body so side effects may remain longer
• vaginal ring - advantages and disadvantages?

  Advantages: 99% Effective with correct use, lasts for 3 weeks Disadvantages: you must be comfortable with inserting and removing it
• patch - advantages and disadvantages?

  Advantages: 99% effective with correct use, lighter and less painful periods Disadvantages: seen in your skin, can cause skin irritation
• IUS - advantages and disadvantages?

  advantages: 99% effective with correct use , works up to 5 years , lighter periods disadvantages : only inserted by medical professional and irregular bleeding