B5- Homeostasis Flashcards
What is homeostasis?
Maintaining internal body conditions
Why is homeostasis important?
To maintain optimum conditions for enzymes and all cell functions
List three things controlled by homeostasis?
- > Body Temperature
- > Blood glucose
- > Water levels
Name the cells that detect a stimulus (change in the environment)?
Receptors
What are two types of effector?
Muscles and glands
Put the following in order for a nerve response:
Effector/stimulus/response/coordinator/receptor
Stimulus->receptor->coordinator->effector->response
A)What is the name given to the glands that produce hormones?
B)how do these hormones reach their target organ?
A) endocrine system
B) through the blood stream
Which part of the body coordinates blood glucose concentration?
Pancreas
Name the hormone that reduces blood sugar levels
Insuline
Describe how blood glucose is controlled if it gets too high?
- pancreas produces insuline
- insuline causes glucose to move from blood into cells
- in the liver and muscle cells, glucose is converted to glycogen for storage
What type of diabetes is inherited?
Type 1
Obesity is a risk factor of which type of diabetes?
Type 2 diabetes
What would a doctor prescribe someone with type 1 diabetes?
Insuline injections
What would a doctor prescribe someone with type 2 diabetes?
- regular exercise
* low carbohydrate diet
In which type of diabetes is no insuline produced?
Type 1 diabetes
In which type of diabetes is insulin still produced but no longer effective?
Type 2 diabetes
Explain how blood glucose concentration is controlled if blood glucose levels are too low.
- pancreas produces glucagon
- glucagon causes liver to convert glycogen back into glucose
- glucose is released back into the blood
Explain how glucagon and insulin interact in the negative feedback cycle.
- If blood glucose levels are too high, insulin is produced by the pancreas which removes glucose from the blood into the liver and muscle cells where it is converted to glycogen.
- If blood glucose levels are too low, pancreas releases glucagon, this stimulates the liver to convert glycogen back into glucose. Glucose is released back into the blood.
A) what three ways is water lost from the body?
B) what two ways are ions lost from the body?
C) what two ways are urea lost from the body?
A) lungs, sweat and urine
B) sweat and urine
C) sweat and urine
Explain the effects that osmotic changes have on cells.
- Osmotic changes cause cells to either gain or lose water
* If they gain or lose too much water they won’t function correctly
Describe how the kidneys maintain the water balance inside the body.
- They control the concentration of urine- controlled by ADH
- If water levels are too high, pituitary gland releases less ADH so that less water Is reabsorbed by the kidneys- more dilute urine.
- If water levels are too low, pituitary glad releases more ADH so more water is reabsorbed by the kidneys- more concentrated urine.
What’s a problem with losing ions, urea and water through the lungs or skin?
There’s no control over how much is lost
Describe how ammonia is produced in the body.
- Protein digestion results in excess amino acids
* In the liver these amino acids are deaminated to form ammonia
How and why does the body get rid of ammonia?
- ammonia is immediately converted to urea
* Because ammonia is toxic so our bodies need to get rid of it quickly
Describe how the kidneys work.
- Kidneys filter waste products out of the blood through filtration
- The right amount of some ions, water and glucose are reabsorbed back into the blood by a process called selective reabsorption.
- Kidneys produce urine containing waste products
Name three substances reabsorbed back in the kidneys.
- Water
- Ions
- Glucose
Describe how ADH controls the water levels in the blood when blood becomes too concentrated.
- ADH released by pituitary gland
* this causes more water to be reabsorbed back into the blood from kidney tubules
Explain why the control of blood water levels by ADH is a negative feedback process.
Higher levels of ADH will lead to the inhibitation of ADH
Explain how dialysis works.
- Patient connected to dialysis machine for 3-4 hours.
- Patients blood flows through a partially permeable membrane surrounded by dialysis fluid.
- Urea, Ions and water diffuse across the membrane into the fluid.
- Dialysis fluid contains the same concentration of ions, water and glucose as healthy blood to maintain appropriate concentration gradient between patients blood and dialysis fluid.
What are the advantages and disadvantages of treating kidney failure with mechanical device or transplant?
Mechanical device: Advantages: -Can keep patient alive until kidney transplant. Disadvantages: -each session takes hours -may cause blood clots -expensive for the NHS
transplant: Advantages: -long term solution and only cure Disadvantages: -risk of rejection -long waiting lists
Give the functions of the following parts of the eye: Cornea Iris Lens Ciliary muscles Suspensory ligaments Retina Optical nerve Sclera
- Cornea-Transparent front layer that bends light Into the eye.
- Iris-Contains muscles that control the shape of the pupil.
- Lens-Focus light on the retina.
- Ciliary muscle-Control the shape of the lens
- Suspensory ligaments-Control the shape of the lens.
- Retina-Contains light receptor cells-Where image is formed.
- Optical nerve-Carries impulses from retina to the brain.
- Sclera-Tough outer layer to protect the eye.
Name the sense organ containing receptors sensitive to light intensity and colour.
The eye
What does ‘accommodation’ mean in terms of eyesight?
The process of changing the shape of the lens to focus on near or far objects.
Describe what happens to the ciliary muscles, suspensory ligaments and lens when focusing on…
A)…near objects
B)…far objects
A) Near objects: Ciliary muscles contract, suspensory ligaments loosen and lens becomes thicker and refracts light strongly.
B) Distant objects: Ciliary muscles relax, suspensory ligaments tighten and lens becomes thinner and light is refracted slightly.
Give the name for the following eyesight conditions:
A) Short sightedness
B) Long sightedness
A) myopia
B) hyperopia
Give three ways in which short and long sightedness are treated.
- Spectacles or contact lenses that refract light to focus on the retina
- Laser eye surgery- changes shape of cornea
- Replacement eye lens
A) What’s the name of the eye condition that means light rays meet before hitting the retina?
B) How would you Correct this?
A) Myopia
B) wear glasses with concave lenses
A) What’s the name of the eye condition that means light rays would meet beyond the retina?
B) How would you correct this?
A) Hyperopia
B) Wear glasses with convex lenses
Name the plant hormone responsible for initiating seed germination.
Gibberellins
A) What is the plant response to light called?
B) What is the plant response to gravity called?
A) Phototropism
B) Geotropism
Name the plant hormone that coordinates and controls growth in plants.
Auxins
Explain how auxins control the growth of a shoot toward light.
- Auxins collect on the shaded side.
- Unequal distribution of auxins…
- …Causes unequal growth rates.
- Growth stimulated on shady side.
- shoot will bend towards the light.
What effect do auxins have on…
A)…Shoots
B)…Roots
A) Stimulates growth
B) Inhibits growth
Name the hormone that controls cell division in and fruit ripening in plants.
Ethene
What three things can auxins be used for in agriculture?
- weed killers
- rooting powder
- promoting growth in tissue culture
What three things can gibberellins be used for?
- End seed dormancy/initiate germination
- Promote flowering
- Increase fruit size
How does the eye change for…
A)…Very bright light?
B)…Dim light?
A) Circular muscles in the iris contract and the radial muscles relax. This causes the pupil to become smaller and reduce the amount of light that enters the eye.
B) Circular muscles relax and the radial muscles contract. This makes the pupil wider and increases the amount of light that enters the eye.
