4.5 Homeostasis And Response Flashcards
What is homeostasis?
The regulation of the internal conditions of a cell or organism to maintain optimum conditions for functions in response to internal and external changes
What does homeostasis maintain in the human body?
Optimal conditions for enzyme action and all cell functions such as blood glucose concentration, body temperature,water levels
What are receptors and what do they do?
Cells that detect stimuli
What is a stimulus?
Changes in the internal or external environment
What are coordination centres and what do they do?
Areas such as the brain , spinal cord and pancreas that receive and process information from receptors
What are effectors and what do they do ?
Areas such as muscles and glands which bring about responses which restore optimum levels
What 2 things do the automatic control systems include ?
Nervous responses in your nervous system and chemical responses in your hormone system
What does the nervous system enable humans to do ?
To react to their surroundings and to coordinate their behaviour
How does the nervous system work ?
-information from receptors passes along sensory neurons () as electrical impulses to the centra nervous system (CNS). The CNS is the brain and spinal cord . The CNS coordinates the responses of effectors which may be muscles contracting or glands secreting hormaones
What are reflexes ?
Rapid automatic responses of the nervous system that do not involve conscious thoughts
What neurones do simple reflexes often have?
Sensory neurons,motor neurone,relay neurons-these connects a sensory neurone and a motor neurone and are found in the CNS
What is the reflex arc?
Bring about a reflex action . They involve the sense organ , sensory neurone relay neurone and motor neurone
Explain the reflex arc ?
Stimulus: A change in the environment is detected by receptors (e.g., skin).
Sensory Neuron: The receptor sends an electrical impulse to the spinal cord via a sensory neuron.
Relay Neuron: The impulse is passed to an interneuron in the spinal cord.
Motor Neuron: The interneuron sends the impulse to a motor neuron.
Effector: The motor neuron signals an effector (muscle or gland) to respond.
Response: The effector carries out the response (e.g., muscle contracts to move your hand away from a hot object).
What is the brain made up of and what does it do?
It controls complex behaviour and is made up of billions of interconnected neurones and has different regions that carry out different functions
What is the cerebral cortex and what does it control?
A regional of the brain which controls memory consciousness,language and intelligence
What is the cerebellum and what does it control?
It is a region in the brain which controls the coordination of muscular activity
What is the medulla nd what does it control?
A regional in the brain which controls unconscious activities such as breathing
What are some of the difficulties of investigating brain functions and treating brain damage and disease?
- brain is complex and delicate
- Most processes involve different neurones in different areas
- Range of chemicals released
- Brain can be easily damaged and destroyed
- Dugs do not always reach the brain through the membranes
- Not completely sure of what each area of the brain actually does
- Easy to cause unintended damage
What is the eye?
A sense organ containing receptors sensitive to light intensity and colour
What is the sclera and what does it do?
The white out layer of the eye , it is fairly tough and strong so the ball is not easy to damage
What is the cornea and what does it do
Thetransparent area at the front of the eyeball which help refract light rays towards the retina
What is the retina and what does it do?
The retina is the light-sensitive layer at the back of the eye. It contains rods (for low light) and cones (for color and bright light). It converts light into electrical signals, which are sent to the brain via the optic nerve to create visual images.
What is the optic nerve and what does it do?
The optic nerve carries electrical signals from the retina to the brain, where the signals are processed to form visual images.
What is the Iris and what does it do?
The iris is the colored part of the eye that controls the size of the pupil, regulating the amount of light entering the eye.
What is the ciliary muscle and what does it do?
Muscles that contract and relax to change the shape of the lens of the eye
What is the suspensory ligament and what does it do?
The ligaments that connect the lens of the eye to the ciliary muscles
What is accommodation?
The process of changing the shape of the lens to focus on near or distant
What happens to the eye if it needs to focus on a near object?
-the ciliarymuscles contract
- the suspensory ligaments loosen
-the lens is then thicker and refracts light rays strongly
What does the eye do if it needs to focus on a distant object?
-The ciliary muscles relax
-the suspensory ligaments are pulled tight
-the lens is the pulled thin and only slightly refracts light rays
What are the 2 common defects of the eyes?
Myopia(short sightedness)and hyperopia (long sightedness) in which rays of light do not focus on the retina
How can myopia and hyperopia treated?
With spectacle lenses which refracts the light rays so that they do focus on the retina
How do u treat myopia ?
To wear glasses with a concave lens that spread out the light from distant objects before it reaches the eye . This means the thicker lens can bring it into perfect focus on the retina
How can u treat hyperopia?
With glasses with a convex lens . They bring the light rays together more before they reach the eye itself . Now the thinner lens can bring the rays of light into perfect focus on the retina
What are the new technology’s used on the eye
Contact lenses
Laser eye surgery
Replacement lenses
What are contact lenses and what do they do ?
Lenses that are placed on the surface of the eye but
What is laser eye surgery?
Lasers are used to treat myopia by reducing the thickness of the cornea slit refracts the light less strongly to treat hyperopia lasers are used to change the curve of the cornea so it refracts light from close objects more effectively
What are replacement lenses?
A permanent contact lens is implanted into the eye and the natural lens is left in place .
Another way is the faulty lens is replaced by an artificial lens .
What is the body temperature monitored and controlled by?
The thermoregulatory centre in the brain
What does the thermoregulatory centre contain?
Receptors sensitive to the temperature of the blood
What does receptors does the skin contain and what do they do?
Temperature receptors and sends nervous impulses to the thermoregulatory centre
What happens if body temperature is too high?
Blood vessels dilate (vasodilation) and sweat is produced from the sweat glands and these cause a transfer of energy from the skin to the environment
What happens if body temperature is too low?
Blood vessels constrict (vasoconstriction) sweating stops and skeletal muscles contract (shiver)
How does vasodilation lower your body temperature ?
Vasodilation lets more blood flow through the capillaries and your skin flushes so u transfer more energy by radiation to ur surroundings, cooling you down
How does sweating cools down down your body?
Sweating cools your body down as water evaporates from your skin transferring energy to the environment
How does vasoconstriction help raise your body temperature?
Reduces blood flow through capillaries so it reduces the energy transferred by radiation through the surface of your skin
How does lower sweat production help raise your body temperature?
Less water from sweat evaporates so less energy is transferred to the environment
How does shivering raise your body temperature?
Shivering needs a lot of respiration ,an exothermic process. The energy from these exothermic reactions raises your body temperature until shivering stops
What is the endocrine system?
The glands that produce the hormones that control many aspects of the development and metabolism of the body and the hormones they produce
What doe the glands from the endocrine system secrete and what do they do?
Hormones which go directly into the bloodstream . The blood then carries the hormone to a target organ where it produces an effect , compared to the nervous system the effects are slower but act for longer
What is the master gland in the brain
Pituitary gland
What does the pituitary gland do?
Secretes several hormones in turn act on other glands to stimulate other hormones to released to bring about effects
What is blood glucose concentration monitored and controlled by?
Pancreas
What happens if the blood glucose concentration is too high?
The pancreas produces the hormone insulin that causes glucose to move from the bloodstream into the cells.
What happens to excess glucose in the liver and muscle cells?
Excess glucose is converted to glycogen for storage
How does insulin control blood glucose levels in the body ?
causes glucose to move from the blood into the cells
What is type 1 diabetes?
A disorder in which the pancreas fails to produce sufficient insulin characterised by by uncontrolled high blood glucose levels
How is type 1 diabetes normally treated?
With insulin injections
What is type 2 diabetes?
A disorder in which the body cells no longer respond to insulin produced by the pancreas
How can type 2 diabetes be treated?
A carbohydrate controlled diet and an exercise regime are common treatments
What is a risk factor for type 2 diabetes?
Obesity
What happens if the blood glucose concentration is tool low?
The pancreas produces the hormone glucagon to be converted into glucose and released into the blood
How to cure type 1 diabetes?
Pancreas transplant and pancreatic cells transplant
How can u treat type 2 diabetes?
Eating a balanced diet
Losing weight
Doing regular exercise
Medication
How does glucagon react with insulin in a negative feedback cycle to control blood glucose levels in the body?
Glucagon travels to the liver in the blood and causes the break-down of glycogen into glucose
How is water lost during exhalation?
Water leaves the body via the lungs during exhalation
What is lost through sweat?
Water , mineral ions and urea are lost through the skin in sweat
What is urea?
The nitrogenous waste product by the breakdown of excess amino acids in your liver
What is lost by no control?
Water through the lungs and water mineral ions and urea by the skin
How is excess water , ions and urea removed?
Via the kidneys in the urine
What happens if body cells lose or gain too much by osmosis?
They do not function properly
What does the digestion of proteins from the diet result in?
Excess amino acids which need to be excreted safely
What happens in the liver to the amino acids?
They are delaminated to form ammonia
What happens once ammonia is formed?
Ammonia is toxic so it is immediately converted to urea for safe extraction
How does the kidney produce urine?
By filtration of the blood and selective re absorption of useful substances such as glucose, some ions and water
What is ADH?
Anti diuretic hormone helps control the water balance of the body and effects the amount of urine produced by the kidney
What is selective reabsorption?
The process in the kidney where the materials needed in the body such as glucose , some mineral ions and water are reabsorbed back into the blood filtrate
What hormone is the water level in the body controlled by?
ADH which acts on the kidney tubules
What is ADH released by and when and what does it do?
By the pituitary gland when the blood is too concentrated and it causes more water to be reabsorbed back into the blood from the kidney tubules
How can kidney failure be treated?
By organ transplant or by using kidney dialysis
What is dialysis?
The process of cleansing the blood through a dialysis machine when the kidney fails
What happens ina dialysis machine?
The concentration of dissolved substances in the blood is restored to normal levels
What does reproductive hormones during puberty cause?
Secondary sex characteristics to develop
Where is oestrogen produced?
In the ovaries
What is ovulation?
At puberty eggs begin to mature and one is released approximately every 28days
Where is testosterone produced and what does it do?
Testosterone isthe main male reproductive hormone produced by the testes and it stimulates sperm production
What are some hormones involved in the menstrual cycle?
Follicle stimulating hormone (FSH)Luteinising hormone (LH)
Oestrogen and progesterone
What does FSH do?
Causes maturation of an egg in the ovary
What does LH do ?
Stimulates the release of the egg
What does oestrogen and progesterone do?
Involved in maintaining the uterus lining
How can fertility be controlled?
By a variety of hormonal and non hormonal methods of contraception
What are some methods of contraception?
Oral contraceptives
Injections implant or skin patch
Barrier methods aka condoms and diaphragms
Intrauterine devices
Spermicidal agents
Abstaining from intercourse
Surgical methods
How do oral contraceptives work?
They contain hormones to inhibit FSH production so that no eggs mature
How do injections implants or skin patches work?
The slowly release progesterone to inhibit the maturation and release of eggs for a number of months or years
How do barrier methods work?
They prevent the sperm reaching the egg
How do intrauterine devices work?
Prevent the implantation of an embryo or release a hormone
How do spermicidal agents work?
It kills or disables sperm
What is IVF?
In VitroFertilisation?
How does IVF work?
Giving a mum FSH and LH to stimulate the maturation of several eggs
The eggs are collected from the mother and fertilised by sperm from the dad in the lab
The eggs develop into embryos
When they are tiny balls of cells 1 or 2 embryos are inserted into the mothers uterus womb
What are some disadvantages to IVF?
It is very emotional and physically stressful
The success rates are not high
It can lead to multiple births which are a risk to both the babies and mum
Where and when is adrenaline produced?
By the adrenal glands in times of fear or stress
What does adrenaline do?
It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for fight or flight
Where is thyroxine produced and what does it stimulate?
The thyroid gland and I stimulates the basal metabolic rate and it plays an impor role in growth and development
What is thyroxine controlled by?
Negative feedback
Why do plants produce hormones?
To coordinate and control growth and responses to light (phototropism)and gravity (geotropism)
What is auxin?
A plant hormone that controls the responses of plants to light and gravity
What are gibberellins?
Plant hormones that are important in initiating seed germination
What are gibberellins important for?
Initiating seed germination
What does ethane control?
Cell division and ripening of fruits
What are plant hormones used in?
Agriculture and horticulture
What are auxins used for?
As weed killers
As rooting powders
For promoting growth in tissue culture
What is ethane used in?
The food industry to control ripening of fruit during storage and transport
What can gibberellins be used for?
End seed dormancy
Promote flowering
Increase fruit size
