Homeostatis And Response Flashcards
What is the function of the iris?
Controls size of pupil and amount of light reaching retina
What is the function of the ciliary muscles and suspensory ligaments?
Can change the shape of the lens to focus on near or distant objects
What is accommodation?
Process of changing the shape of the lens to focus on near or distant objects
To focus on near objects?
^Ciliary muscles contracting
^Suspensory ligaments loosen
^Lens becomes thicker
^Lens strongly refracts light rays
What does the eye do to focus on distant objects?
👁 Ciliary muscles relax
👁Suspensory ligaments are pulled tight
👁Lens is pulled thin
👁Lens slightly refracts light rays
What are the 2 common defects of the eye?
👁Myopia - short sightedness
👁Hyperopia - long sightedness
What does it mean if your eye has a common defect?
When rays of light do not focus on the retina
How can myopia and hyperopia treated?
With spectacle lenses that refract the light rays so they can focus on the retina
Why does our pupil become smaller when exposed to bright light?
To protect the retina from damage
Name some new eye treatment technologies?
*Contact lenses
*Laser eye surgery (changes cornea shape)
*Eye lens replacement
What is the endocrine system?
Made up of glands which secrete hormones directly into the bloodstream
What are hormones?
Chemical messengers carried in the blood
What do hormones do?
Hormones target organs where they produce an effect
What is the difference between the effects of hormones and the nervous system?
Compared to the effects of the nervous system, hormones are slower and act for longer
What is the pituitary gland?
It’s the master gland
Where is the pituitary gland found?
In the brain
What is the function of the master gland?
Secrete hormones in response to body conditions, some of the hormones act on other glands to stimulate other hormones to be released to bring about effects
What does adrenaline do?
●Produced by adrenal glands in times of fear or stress
●Increases heart rate which increases the delivery of oxygen and glucose to the brain and muscles
●Preps body for fight or flight
Where is thyroxine produced?
In the thyroid gland
What is the function of thyroxine?
£Increases metabolic rate
£Controls growth and development in young animals
How is the release of thyroxine controlled?
By negative feedback
Why might the endocrine glands be called ductless glands?
Enzymes from glands (like the salivary gland) pass into tubes called ducts, the endocrine system can be called ductless because the hormones pass into the blood
Where is blood glucose concentration monitored and controlled?
The pancreas monitors and controls the blood glucose concentration
What happens when blood concentration is too high?
Pancreas releases more insulin (hormone)
#Insulin causes glucose to move from the body into cells like fat and muscle cells so they can use glucose for energy
#Liver and muscle cells convert excess glucose into glycogen for storage
What happens when blood glucose concentration is too low?
<Pancreas releases glucagon
<Glucagon stimulates glycogen to be converted into glucose and released into thr blood
<Negative feedback
Describe type 1 diabetes?
*Caused by pancreas failing to produce enough insulin
*Results in uncontrolled high blood glucose levels
*Usually treated with insulin injections
What is negative feedback?
Action taken by the body to return something in the body back to normal/optimum level when that something wasn’t at the right level
State the 3 ways water leaves the body?
Water leaves the body from the lungs during breathing, skin when sweating and urine
When concentration of blood changes, what happens to the body cells?
If concentration of blood changes, body cells will LOSE OR GAIN TOO MUCH WATER BY OSMOSIS (high concentration to low concentration )
Where is the balance of water and ions in the body regulated?
In thr KIDNEYS AND THEY ALSO EXCRETE UREA
What is urea?
A WASTE PRODUCT PRODUCED BY THE LIVER FROM THE BREAKDOWN OF PROTEINS and contains nitrogen
What does the digestion of proteins result in?
The digestion of proteins from food results in EXCESS AMINO ACIDS
What happens to the excess amino acids produced from the digestion of proteins from food?
CONVERTED INTO AMMONIA IN A PROCESS CALLED DEAMINATION
What is deamination?
BREAKDOWN OF EXCESS AMINO ACIDS
Is ammonia toxic?
YES
Ammonia is toxic, so what happens to it in the body?
IMMEDIATELY CONVERTED TO UREA AND SWNT TO THE KIDNEYS FOR SAFE EXCRETION
What is the control of the water level in the body an example of?
NEGATIVE FEEDBACK
The three steps the kidneys produce urine?
1) Filter the blood
2) Selective reabsorption of useful substances such as glucose, some ions and water
3) Leaves urea and excess water and ions to form urine
Where does the process of the kidneys producing urine take place?
These processes take place in MILLIONS OF SMALL TUBES IN THE KIDNEYS CALLED TUBULES
What is selective reabsorption?
Process of active transport (low to high) that reabsorbs useful molecules back into the blood from kidney tubules
What hormone controls water level?
The water level in the body is controlled by the hormone ADH
How does the hormone ADH work?
*ADH IS RELEASED BY THE PITUITARY GLAND WHEN THE BLOOD IS TOO CONCENTRATED (high concentration of red blood cells)
*IT PASSES, IN THE BLOOD, TO THE KIDNEY TUBULES WHERE IT CAUSES MORE WATER TO BE REABSORBED BACK INTO THE BLOOD
How are people who suffer from kidney failure treated?
BY ORGAN TRANSPLANT OR BY USING KIDNEY DIALYSIS
How does dialysis work?
TAKES OVER THE ROLE OF KIDNEYS , USED TO REMOVE WASTE PRODUCTS FROM THE BLOOD, THREE TIMES A WEEK
What play many roles in human reproduction?
Hormones
What do sex hormones cause to happen during puberty?
During puberty, sex hormones cause SECONDARY SEXUAL CHARACTERISTICS TO DEVELOP (OESTROGEN+TESTOSTERONE)
What is the main female sex hormone?
Oestrogen
Where is oestrogen from?
Ovaries
What happens for females when they hit puberty?
Eggs begin to mature and be released = ovulation
What is the main male sex hormone?
Testosterone
Where is testosterone produced and what does it do?
●Produced by testes
●Stimulates sperm production
What is the difference between the production of sex hormones in men and women?
After puberty, MEN PRODUCE SPERM CONTINOUSLY, WOMEN HAVE A MONTHLY CYCLE OF EVENTS (menstrual cycle)
How many hormones are involved in a woman’s menstrual cycle?
Four hormones
Name the four hormones involved in a woman’s menstrual cycle?
♡Follicle stimulating hormone(FSH)
♡Oestrogen
♡Lutenising hormone (LH)
♡Progesterone
Where is the follicle stimulating hormone (FSH) secreted during the menstrual cycle?
By the pituitary gland
What does the follicle stimulating hormone cause during the menstrual cycle?
■Causes egg to mature in ovaries in the first part of thr cycle
■Stimulates ovaries to produce oestrogen
Where is oestrogen secreted during the menstrual cycle?
By ovaries
What does the oestrogen hormone cause during the menstrual cycle?
♡Inhibts (prevents) FSH release
♡Stimulates LH release
♡Makes uterus lining grow again after menstruation
Where is the lutenising hormone secreted by during the menstrual cycle?
●Secreted by pituitary gland
What does the liutenising hormone do during the menstrual cycle?
Stimulates release of egg from the ovary (ovulation)
Where is progesterone secreted by during the menstrual cycle?
Secreted by an empty follicle (egg sac) in the ovaries
What is the function of progesterone during the menstrual cycle?.
♡Maintains lining of uterus during the second half of the cycle
♡Inhibts (prevents) FSH release and LH release
What is a follicle in a woman?
An egg sac
What do contraception and fertility treatments raise concerns of ?
Ethical issues
Can plants respond to changes in their external environment?
Yes
How do plants respond to changes in their external environment?
🌻Roots and shoots growing towards or away from a particular stimulus (anything that triggers a change)
🌻Plants flowering at a particular time
🌻Ripening of fruits
Are plants responses to changes faster or slower than animal responses?
Slower than animal responses
What is it called when a plant responds by growing in a particular direction?
Tropism
What is tropism?
When a plant responds by growing in a particular direction
How many types of tropism are there?
2, Gravitropic and Phototropic
Describe gravitropic in terms of the shoots?
🌸Growth of the shoots is negatively gravitropic (geotropic)🌸Stem grows against force of gravity = upwards
Describe gravitropism is terms of the roots?
🌸Growth of roots is positively geotropic as the roots grow in the direction of gravity = downwards
What is gravitropic?
When the stimulus (change) is gravity. For example the plant is placed on its side. Shoots are negative and roots are positive geotropic
What is phototropism?
The stimulus (change) is light
Describe phototropism in terms of the plant shoots?
Plant shoots grows towards the light = positively phototropic
Describe phototropism in terms of the roots?
Roots grow away from the light = negatively phototropic
What are auxins?
A plant hormone which controls tropisms
What plant hormone controls tropisims?
Auxins
What happens to auxin in response to light?
1) Auxin diffuses down the shoots stimulating growth
2) One side of the shoot is in the light so auxin diffuses away into the shade
3) Shoot in the shade has more auxin so grows faster causing the shoot to be more elongated and bends towards the light
Describe how the roots change in a response to gravity?
Auxin moves to the bottom of the root, causes less elongation so root grows downwards, growth inhibited (reduced)
Define homeostasis?
The regulation of the internal conditions of a cell or organism in response to internal or external changes
Why is homeostasis important?
Important as it keeps conditions constant for enzyme action and cell functions
What is thr function of the cerebellum?
Coordinates movement and balance
What does the medulla control?
Controls automatic/conscious actions like heart bear and breathing
What is the function of the optic nerve?
Carries impulses from the retina to the brain
What is the sclera?
Forms a tough outer layer, transparent region at the front called the cornea
What organ is the eye?
A sense organ
What does the retina contain?
Contains receptors cells that are sensitive to brightness and light
What is negative feedback?
An important type of control, responds when conditions change from ideal so returns conditions back to ideal, continuous cycle
What temperature should the human body be?
Around 37.c
Why should the body be at 37.c ?
Its an optimum temperature for enzymes to work
What sort of behaviour does the brain control?
Complex behaviour
What is the brain made from?
Billions of inter connected neurones and has different regions thar carry out different functions
What happens when the body temperature gets too high?
●Blood vessels widen, directing more blood to the surface of skin ( Vasolidation)
●More sweat produced from sweat glands and evaporates
What is the function of the thermoregulatory centre?
●monitors and controls body temp
How does the thermoregulatory center know when to act?
●Receptors that monitor the temp of blood flowing through the brain
●Recieves info (impulses) from temperature receptors in skin
Where is the thermoregulatory center located?
In the brain
Why are thr temperature receptors in the skin useful?
Give thr brain an early warning of changes in external temperature, allows temperature to be adjusted to stop body temperature changing, like putting on more clothes
Blood vessels in the skin can’t move so what happens to change energy transferred to surroundings?
They narrow or widen to adjust how much energy is transferred to the outside
Homeostasis includes the control of …?
●Blood glucose
●Body temperature
●Water and ion levels (like potassium and calcium)
What control systems does homeostasis control?
●Responses using nerves
●Chemical responses using hormones
What are the 3 stages og negative feedback?
1) receptors detects a change in stimulus
2) the coordinating centre compares the stimulus to a set point
3) an effector produces a response to correct any difference from the set point
What are control systems?
Cells called receptors detect stimulus (change in environment)
What do coordinating centres do and name some?
Recieve and process info from receptors. Brain, spinal cord, pancreas
What are efffectors and give an example?
They are muscles or glands which bring about responses that restore optimum levels
What is the cerebal cortex responsiblefor?
Responsible for consciousness, intelligence, memory and language
How are neuroscientists able to map out the brain regions to particular functions?
●Studying patients with brain damage
●Electrically stimulate different parts of the brain
●MRI scanning techniques
Why is investigating the brain difficult?
Because of its complexity and delicacy
What are the 5 step of the reflex actions?
1) pain stimulus detected by receptors
2) impulses from receptors pass along the sensory neurone to the CNS
3) impulse passes through a relay neurone
4) motor nuerone carries an impulse to the effector
5) effector (usually muscle) responds ie by removing hands from source of pain
Do reflex actions involve the brain?
No, don’t involve the conscious part of thd brain
How do neurones communicate?
Communicate via synapses
What are the three main brain regions?
☆Cerebal cortex
☆Cerebellum
☆Medulla
What is the function of the nervous system?
Allows humans to react to their surroundings and coordinate their behaviour
What is thr CNS?
The centeral nervous system
Where is the CNS located?
Brain and spinal cord
What is the function of thr CNS?
Coordinates the response of the effectors. For example muscles contracting or sweat glands secreting hormones
What happens if body temp is too low?
● blood vessels narrow directing blood away from surface of skin (vasconstriction)
●Sweating stops
●Skeletal muscles contracting and relax quickly shiver (which transfers more heat to the blood)
What happens when skeletal muscles contracting and relax quickly when body temp is too low?
shiver which transfers more heat to the blood)
Where does deamination happen?
In the LIVER
What are reflex actions?
Automatic and rapid so they can protect the body from danger
