SB7 Flashcards
Animal coordination, control and homeostasis
What are hormones
Chemical messengers
How are hormones transported
Through the blood
What is meant by the endocrine system
The various glands that secrete hormones into the blood
What is the difference between the endocrine and nervous system
- ES uses chemical messengers, NS electrical impulses
- ES is slower and lasts longer, NS is quick and lasts shorter
- ES act generally, NS is precise
What are the endocrine glands, hormones and location
- Pituitary - FHS, LH, ADH, TSH, TRH -brain
- Adrenal - Adrenaline - Above kidneys
- Thyroid - Thyroxine - Neck
- Pancreas - Insulin + Glucagon - Abdomen
- Ovaries - Oestrogen + Progesterone - Pelvis
- Testes - Testosterone - Pelvis
Define homeostasis
The regulation of the internal conditions to maintain optimum conditions
Define target cells/organs
Tissues that have receptors for specific hormones - allowing hormones to trigger sudden changes
Why is it important to maintain homeostasis
To ensure the survival and function of all cells and the body
What is negative feedback response
The body’s attempt to counteract and reverse any external or internal stimuli to maintain homeostasis
Why is adrenaline produced
- The body has an increased demand for oxygen
- To prepare the body for action/ ‘fight or flight’
State the target organs of adrenaline
- Heart
- Liver
State the effects of adrenaline
- Increase blood pressure to increase oxygen + energy supply to muscles
- Increases blood sugar level - break down of glycogen stores
- Increased breathing rate (bronchioles widen)
- Increased heart rate
- Redirects blood flow to digestive system
- Pupil dilation
Why is thyroxine produced
- To regulate metabolism
- To control body’s energy production
State the target organs of thyroxine
- All cells
- Digestive system
What is the negative feedback response loop of thyroxine
- Hypothalamus detects low level of thyroxine and releases TRH
- TRH stimulates pituitary to release TSH
- TSH stimulates thyroid to release more thyroxine
- Thyroxine levels become too high
- Inhibits release of TRH + TSH
What is it called when you have too little thyroxine
Hypothyroidism
What are the effects of hypothyroidism
- Weight gain
- Increased heart rate
- Loss of appetite
- Reduced fertility
What is it called when you have too much thyroxine
Hyperthyroidism
What are the effects of hyperthyroidism
- Weight loss
- Palpitations
- Irregular menstrual cycle
- Irritability
State the target organs of insulin
- Most cells (respiration)
- Muscles
- Liver
What is the target organ of glucagon
- Liver
What are the effects of insulin
Tells tissues to absorb excess glucose (which then produces glycogen)
What are the effects of glucagon
Tells tissues to break down glycogen to form glucose
What is glycogen
The long term storage form of glucose
How is glucose absorbed into the bloodstream
Through the consumption of carbohydrates
What happens when the blood glucose levels are too high
- Pancreas detects this
- Releases Insulin
- Insulin binds to liver, muscles and most cells
- They absorb glucose and store it as glycogen
- Blood glucose levels fall back to normal
In what ways can blood glucose levels fall
- Vigorous exercise
- Skipping meals
What happens when the blood glucose levels are too low
- Pancreas detects this
- Releases glucagon
- Glycogen breaks down to form glucose
- Glucose released into bloodstream
- Blood glucose levels rise back to normal
What is the cause and effect of Type 1 diabetes
- Autoimmune disease
- Pancreatic cells are killed
- Little - no insulin produced
What is the cause and effect of Type 2 diabetes
- Lifestyle
- Body cells become resistant to insulin
- Not enough insulin is produced
How is Type 1 diabetes controlled
- Injecting insulin into the subcutaneous tissue of the thigh or abdomen
- Exercising a lot - muscles absorb more glucose
- Low carb/sugar diet
How is Type 2 diabetes controlled
- Low carb/sugar diet
- Exercising a lot
What are the four hormones involved in the menstrual cycle
- FSH
- Oestrogen
- LH
- Progresterone
What are the stages of the menstrual cycle
- Stage 1: Day 1-5, menstruation occurs, uterus lining breaks down
- Stage 2: Day 5-14, uterus lining builds up again
- Stage 3: Day 14, ovulation occurs
- Stage 4: Day 15-28: uterus lining is maintained in case of fertilisation
What is the function of FSH and what stage is it released in
- Stimulates maturation of egg and follicle
- Stage 1
What is the function of oestrogen and what stage is it released in
- Builds up uterus lining
- Stage 2
What is the function of LH and what stage is it released in
- Ruptures egg follicle and the remains form corpus luteum
- Stage 3
What is the function of progesterone and what stage is it released in
- Released from corpus luteum
- Maintains uterus lining
- Creates thick mucus
- Stage 4
Define puberty
When adolescents develop their secondary sex characteristics
Give examples of pubic changes
- Men grow facial hair
- Women develop breasts
Define contraception
An artificial method used to prevent pregnancy
What are the hormonal methods of contraception and how long do they last
- The pill - 1 day
- Patch - 1 week
- Injection - 3 months
- Implant - 3 years
- IUD - 5-10 years
How do hormonal contraceptives work
- They slowly release oestrogen and/or progesterone
- They inhibit the release of FSH and LH - egg cant mature
What are the advantages of hormonal contraceptives
+ Reliable
+ (Some) are long lasting
+ Reduced period pain
What are the disadvantages of hormonal contraceptives
- Do not protect from STI
- Cause nausea and headaches
- Weight gain
- Acne
- Change in blood pressure
What are the physical methods of contraception and how do they work
- Condom - catch and kill sperm
- Diaphragm - prevent sperm from entering the cervix
- Spermicide - kills sperm
- Copper IUD - kills sperm
How do physical contraceptives work
Prevent sperm from reaching egg
What are the advantages of physical contraceptives
+ They can protect from SDI
+ Quick and easy
What are the disadvantages of physical contraceptives
- Can break or tear
- Aren’t 100% reliable
Define sterilisation
A surgery making a human incapable of producing offspring
How does sterilisation work
- Vasectomy - cutting and tying sperm ducts to prevent sperm leaving
- Tube ligation - fallopian tubes blocked and sealed to prevent egg reaching uterus
What is the most reliable form of contraception
- Abstinence
What is ART
- Assistive Reproduction Therapy
- Use of artificial hormones to trick body into producing an embryo
What is clomifene therapy
- Women’s pituitary gland may not produce enough FSH
- A drug that contains FSH and LH is given to her
- Follicle can now mature and ovulation can occur
What is IVF
In Vitro Fertilisation
When is IVF considered
If clomifene therapy is ineffective
What are the steps of IVF
- Egg follicle maturation is stimulated via hormones
- Egg released by many follicles and are taken out of ovary into a lab
- Man’s sperm is collected
- Eggs are fertilised (sometimes by injecting sperm into egg ICSI)
- Multiple embryos are placed back into the uterus
Advantages of IVF
+ Infertile couples have a chance at having children
+ Unused embryos can be donated
Disadvantages of IVF
- Expensive
- Not always successful
- Multiple births increase chance of complications e.g. miscarriage
Define osmoregulation
Maintenance and regulation of water levels in blood
What roles do the kidneys have
- Regulate water levels
- Regulate ion levels
- Remove waste
What happens if an animal cell is placed in a hypotonic solution
- Hypotonic - higher concentration of water outside of cell
- Water moves into cell
- Cell becomes turgid
- Lysis occurs (no cell wall to keep structure)
What happens if an animal cell is placed in a hypertonic solution
- Hypertonic - higher concentration of water inside cell
- Water moves out of cell
- Cell becomes flaccid
- Crenation occurs (membranes wrinkles)
What organ is responsible for managing water levels
Kidney
What is a nephron
A filtration unit in the kidney
How does blood flow to the kidney
Through the renal artery
How does blood flow out of the kidney
Through the renal vein
What is urea
The products of deamination
What is deamination
The breakdown of excess amino acids in blood
Why is it important to filter out urea
It is slightly poisonous
Explain the process of filtration (kidneys)
- Liquid part of blood is forced out of glomerulus into the Bowman’s capsule at a high pressure
- Bigger molecules (protein and blood cells) are too large to be forced through
Explain the process of selective reabsorption
- Fluid passes through proximal convulated tubule - loop of Henle - distal convulated tubule - collecting duct
- As fluid passes necessary substances are reabsorbed
- All glucose, some water + ions
What is urine
Anything that flows out of the collecting duct
How is urine excreted
It passes through the ureters to the bladder to the urethra
How does the negative feedback response work in osmoregulation
- Hypothalamus monitors and detects changes in water level
- If water levels decrease, it sends signal to pituitary to release ADH
- ADH increases the permeability of the collecting duct = more water reabsorbed
- Less urine produced
What is ADH
Anti-diuretic hormone
What is the danger of kidney failure
- Unable to regulate water + ion levels
- Unable to remove waste
Explain the process of dialysis
- Patients blood flows through dialysis fluid in a semi permeable membrane
- DF contains attributes of healthy blood e.g. normal water + ion levels, glucose, amino acids
- Concentration gradient established between blood and DF
- Excess water + ions, urea etc. diffuse out through the semi permeable membrane
- Filtered blood is put back into body
Why is the dialysis fluid constantly replaced
Concentration gradient will eventually reach equilibrium
Advantages of dialysis
+ Available to anybody
+ No drugs taken
Disadvantages of dialysis
- Time consuming (9-16h a week)
- Lifelong commitment
- Expensive
Describe features of a kidney transplant
- New kidney is placed lower - close to bladder
- New kidney is first tested for at least six matched antigens - reduce chance of rejection
Advantages of kidney transplant
+ Cheaper for NHS overall
+ Patients can lead a normal life
Disadvantages of kidney transplant
- Only lasts 8-9 years
- Need immunosuppressive drugs
- Surgery is risky
- Hard to get organs
- Chance of rejection
Define thermoregulation
Maintenance of temperature levels
Why is thermoregulation important
To ensure enzymes do not denature
Describe the role of the hypothalamus in thermoregulation
- Has a thermoregulatory centre that receives signals from heat receptors in the epidermis and the dermis
- Skin detects external temperature
Describe what happens if you are too hot
- Sweating
- Vasodilation
Purpose of sweating
- Water excreted evaporates = increase heat loss
Process of vasodilation
- Arteriole dilates - smooth muscle in walls dilate
- Increased blood flow to capillaries (close to skin surface)
- Increased heat loss out of body
- Less flow of blood through shunt vessel
Describe what happens if you are too cold
- Shivering
- Goosebumps
- Vasoconstriction
Process of shivering
- Repetitive muscles contractions = increased respiration in muscles = increased energy out
- Heat produced
Process and purpose of goosebumps
- Pili erector muscles contract
- Hairs trap insulating bubble or air
- Increase heat
Process of vasoconstriction
- Arteriole constricts - smooth muscle wall contracts
- Less blood flow to capillaries
- Less heat lost through skin
- More blood flows through shunt valve = reduce heat loss
