health Flashcards
The following three steps:
1. A change in the body is detected (e.g.: a change in
temperature or glucose level).
2. A message is sent to a gland or organ. (Note: In
some cases this may be a multi-step process.)
3. A response is initiated. The response retu ns the
body to its no mal state.
is an example of
negative feedback
Conditions inside the human body remain fairly constant despite changes in the exte nal
environment, this is known as
homeostasis
In the retina of the eye, light is detected by
photoreceptors
The dark spot in the centre of your eye is called the pupil. Your pupil is simply a hole in the iris. Your iris
is the coloured part of your eye
The photoreceptors in the retina respond to the light stimuli by sending signals to
your _______________ which then fo wards them to your brain for interpretation.
optic nerve
There are three different types of neurons: senso y neurons, which ca y the impulse
generated by the stimulus to the central ne vous system; inte neurons, which then ca y the
impulse through the central ne vous system; and motor neurons, which
take the impulse to effectors such as muscles or glands.
An axon, which is a long st ucture through which the ne ve impulse passes along. There are
axon branches at the end of the axon. The axon is elect ically insulated by a sheath or
cove ing made of ____________.
myelin
Ne ve impulses travel along a neuron in one direction only — from
dend ite to axon branch
Photoreceptors in the retina of the eye detect light. There are two types of photoreceptor:
rods and cones. Rods cannot detect colour, but only low light is needed to t igger a ne ve
impulse from rod cells. Cones are involved in colour vision. In humans cone cells respond to
_______, _______ and ________ light respectively.
blue, red and green
Describe an example of negative feedback to maintain homeostasis
If the temperature drops, the body shivers to bring up the temperature and if it is too warm, the body will sweat to cool down due to evaporation.
Outline the role of the kidneys in maintaining water balance.
The kidneys can regulate water levels in the body; they conserve water if you are dehydrated, and they can make urine more dilute to expel excess water if necessary.
Recall the 4 main types of receptor cells.
chemoreceptors, thermoreceptors, photoreceptors and mechanoreceptors.
Describe the structure of the eye.
The outermost coat consists of the cornea and the sclera; the middle coat contains the main blood supply to the eye and consists, from the back forward, of the choroid, the ciliary body, and the iris.
Outline the function of the endocrine system
The endocrine hormones help control mood, growth and development, the way our organs work, metabolism , and reproduction. The endocrine system regulates how much of each hormone is released. This can depend on levels of hormones already in the blood, or on levels of other substances in the blood, like calcium.
What is the role of the Hypothalamus in the endocrine system?
This organ connects your endocrine system with your nervous system. Its main job is to tell your pituitary gland to start or stop making hormones.
What is the role of the Pituitary gland in the endocrine system?
The pituitary gland is called the ‘master gland’ as the hormones it produces control so many different processes in the body. It senses the body’s needs and sends signals to different organs and glands throughout the body to regulate their function and maintain an appropriate environment.
What is the role of the Pineal gland in the endocrine system?
This gland makes a chemical called melatonin. It helps your body get ready to go to sleep.
