Endotherms And Ectotherms Flashcards
What are positives and negatives for ectotherms?
Positives -
- Use less food for reparation to generate heat.
- Eat less food, don’t need to eat as frequently.
- So can use more energy from food for growth respiration.
Negatives-
- conditions = more vulnerable to predators = can’t search for food.
- Need to hibernate as unable to be active in cooler months.
- Limited to where they can live.
Positive and negatives for endotherms.
Positives-
- Have a constant body temp, so constant metabolic rate.
- Can stay active regardless of external changes in temp.
- Can live in extreme climates.
Negative-
- Lots of energy used up in maintaining body temp.
- Need to consume more food to fuel respiration.
- Less energy from consuming food is used in growth and reproduction.
What behavioural mechanisms do ectotherms do to regulate body temp?
Ways to gain heat:
- Bask in sun directly.
- Lie on hottest surfaces.
- Increase their SA (spread out).
- Huddling together at night.
- Frills around neck - stand up - warms up blood in that area
Ways to lose heat:
- find shade - burrows.
- Lower SA.
- Reduce movements
Psychological mechanisms for ectotherms to regulate body temp.
- Change colour of skin -> darker absorbs more heat, lighter = less.
- Change heart/metabolic rate -> less heat generated.
- Structural adaptions -> more heat adsorption.
How do endotherms regulate body temp?
- Thermoreceptors in hypothalamus detect temp of blood when it passes through brain.
- Peripheral thermoreceptors in skin detect external air temp at skin surface.
These send nerve impulses to hypothalamus along sensory neurones -> nerve impulses travels along autonomic motor neurons to effectors, which respond by restoring normal body temp (around 37 degrees Celsius).
What happens at heat loss centre?
- Activated when temp of blood flowing through hypothalamus increases.
- Impulse sent along autonomic motor neurons to the effectors.
-Triggers responses to decrease core body temp.
What happens at heat gain centre?
- activated when temp of blood flowing through hypothalamus decreases.
- Impulses sent along autonomic motor neurons to the effectors.
- Triggers responses to increase core body temp.
When do endotherms use these centres?
- Endotherms use their internal exothermic metabolic reactions to keep them warm (e.g. resp).
- Use energy requiring psychological responses to cool them down.
What are corrective mechanisms for heat loss?
- Vasodilation -> arteries dilate so more blood enters the capillaries, meaning more energy is transferred from radiation/lost, cooling them down.
- Increase sweating -> water has high latent heat of evaporation, meaning lots of heat energy needed to convert liquid sweat to gas, so heat carried away from body.
- Hairs lie flat -> decrease SA.
- Metabolic rate drops ( decrease adrenaline and thyroxine released, no shivering) -> muscles don’t have to control and relax, using resp -> so less heat is released.
Corrective mechanisms for heat gain.
- Vasoconstriction -> arteries constrict so less blood enters capillaries, meaning less energy is transferred from radiation , heating them up.
- less sweating -> less heat carried away from body.
- Hairs stand up -> increase SA.
- Metabolic rate increases -> muscles contract causing shivering -> using resp so more heat released.
What is vasodilation and constriction?
- Arterioles lead to capillaries.
- These constrict/ dilate as capillaries have no smooth muscle, made up of 1 cell thick endothelium, which cannot constrict/dilate.
Hormones in thermoregulation?
Increase body temp.
- Adrenaline - from adrenal gland - used in short term - increase basal metabolic rate, increase cell respiration = more heat generated from cell.
- Thyroxine - from thyroid gland = increase BMR, generate more heat.
Behavioural mechanisms for endotherms.
Warming up -
- basking in sun
- Huddling together in groups.
- Increase activity - muscle contraction, resp, more heat generated.
- Put more clothes on.
Cooling down -
- Bathing in mud/water.
- Moving into burrows.
- Decreasing activity = less heat.
- Remove clothes.
Why is thermoregulation maintained within certain environmental limits?
- If the temp is extreme for long time, homeostasis can’t bring it back down -> core body temp rises/falls beyond safe level.
- Changes in temp affects enzymes.
What are the 2 conditions of thermoregulation?
Below 36 degrees - hypothermia, below 35 degrees Celsius - life threatening
- shivering, confusion, memory loss, dizziness.
Above 38 degrees - hyperthermia, above 40 degrees - life threatening
- Excessive sweating, exhaustion, red skin, nausea, headache
