chapter 15 hormones Flashcards
how does insulin decrease BGC
- Increasing permeability of cell membranes to glucose = increase rate of glucose uptake by cells
- Stimulating liver and muscle cells to convert excess glucose into glycogen for storage
- increasing oxidation of glucose during tissue respiration
effects of insulin being overly secreted
Abnormal decrease in BCG = hunger and irritability
Low BCG can lead to shock
Can lead to coma and death
effects of lack of insulin secretion
- Glucose cannot be converted to glycogen for storage = abnormally high BCG
- Muscle cells have no reserves of glycogen = body grows weak and loses weight
- Body oxidises fats instead of glucose (in respiration) to release energy = produces poisonous substances, ketones
- Glucose itself cannot be stored/utilised by tissue cells = glucose lost in urine = gives rise to a disease called diabetes mellitus
when does diabetes mellitus happen + symptoms
→happens when body has insufficient insulin secretion: unable to control BCG within norm = BCG can rise and exceed kidney’s ability to completely reabsorb glucose = non selectively reabsorbed glucose is excreted in urine
→ signs of DM:
1. Constantly high BCG
2. Presence of glucose after a meal
3. Slow and difficult healing of wounds (platelets unable to clot blood)
type 1 diabetes (early onset) - cause + treatment
cause: IOL are unable to produce/secrete sufficient insulin from a young age -> target cells will still respond to the lesser insulin
I
treatment
1. inject insulin regularly (if taken orally, may be digested as insulin is made of protein)
2. Have a supply of sugary food to raise up BG if they exercise too much, eat too little or use too much insulin (when injecting)
type 2 diabetes (late onset)
cause: Insulin is produced but target cells (eg muscle cells) do not respond well to insulin → develops more in overweight people
treatment:
1. Regulate carbohydrate content in diet
2. Exercising
how does glucagon increase BGC
- stimulating liver cells to convert glycogen to glucose = release into the bloodstream
- If glycogen runs out: stimulates liver cells to convert fats/amino acids/lactic acid into glucose
nervous pathway of adreanaline secretion
pathway:
1. Brain is aware body is stressed = sends nerve impulses to relay neurone
2. relay neurone sends impulses down spinal cord to motor neurone
3. Motor neurone transmits impulses to adrenal gland (effector gland) = adrenal gland stimulated and produces adrenaline
4. Adrenal gland secretes adrenaline into bloodstream
5. Blood vessels in blood transports adrenaline to target organs = respond with short term effects of adrenaline to prepare for flight or fight response
effects of adrenaline (9)
- Increase rate of breakdown of glycogen to glucose in liver and muscle = increases blood glucose level
- Increase metabolic rate = release more energy during tissue respiration
- Increase rate of heartbeat + increase in blood pressure = glucose and oxygen are carried faster in blood to muscles
- Increase rate and depth of breathing = increase rate of oxygen uptake for the much needed cellular respiration to release energy
- Constricts arterioles in skin = channel more blood to muscles (like in the limbs) - causes paleness in face [less blood is carried to skin = less heat loss due to CCR (vasoconstriction)]
- Constricts arterioles to the gut = decrease digestive activities
- increase rate of blood coagulation = prevent further/excessive blood loss if there is a cut = increase rate of survival
- Pupil will dilate = more light enters the eye = enhances vision
- Contract hair erector muscles = hair stands on end, skin around hair is raised = forms goosebumps = standing hair traps a layer of air = prevent further heat loss
similarities between hormonal and nervous coordination (4)
- A detector that detects a stimulus
- A signal or message that is transmitted
- An effector (target organ that carries out the response)
- Both co-ordinate by transmitting information to target organs to elicit changes in response to stimulus
differences between endocrine and nervous system (6)
Area of comparison
Endocrine System (ES)
Nervous System (NS)
- ES Involves hormones (chemical substances) but NS involves nerve impulses (electrical signals)
- Mode of transmission: Hormones transmitted by bloodstream vs Impulses are transmitted by neurones
- Time it takes for effector to take effect: Slower response and transmission in ES but quick response and transmission in NS
- Duration of effects: Can be long-lived/short-lived depending on the type of hormone vs Short lived effects in NS
- Type of action/response: Always involuntary in ES but voluntary or involuntary in NS
- location(s) of effector: May affect more than one organ (widespread effects) in ES but localised (in one organ only) in NS
