y4.1 endocrine system 🏃♂️ Flashcards
what is a gland?
a gland is a group of cells that produces and secretes chemicals for release, such as enzymes or hormones
function and examples of endocrine glands
secrete hormones directly into the bloodstream to specific target cells or organs
examples include: pancreas, pituitary gland, adrenal gland
what are hormones?
hormones are chemical substances, produced by an endocrine gland, carried by the blood, which alters the activity of one or more specific target organs and is then destroyed by the liver
characteristics of hormones
- small, soluble molecules
- effective in low concentration
- produced by one organ
- secreted into ad carried to all parts of the body by blood
- is specific in action
process of adrenaline secretion
- stimulus (fear, stress, anger) is detected by hypothalamus in the brain
- hypothalamus generates nerve impulses which travel along the relay neurone to the spinal cord
- neurotransmitters are released across the synapse between relay and motor neurone
- nerve impulse travels along the motor neurone to the adrenal gland
- adrenal gland is stimulated to secrete adrenaline into the bloodstream
effects of adrenaline secretion
- stimulates liver and muscles to speed up breakdown of glycogen into glucose to increase blood sugar levels
- stimulates lungs to increase rate and depth of breathing to take in more oxygen
- stimulate heart to increase rate of heartbeat and increase blood pressure to transport oxygen and glucose faster to the muscles
- stimulate arterioles in skin to constrict, channeling more blood to the muscles (causes paleness)
- stimulates pupils to dilate to enhance vision
similarities between nervous and hormonal coordination
1) both provide pathways of communication within the body to coordinate various activities
2) both involve the transmission of messages to the effectors
differences between nervous and hormonal coordination
1) nerve impulses (electrical) and neurotransmitters (chemical) vs hormones (chemical)
2) transmitted along neurones vs in the bloodstream
3) rate of transmission rapid vs relatively slow
4) restricted to structures linked to the related neurones vs widespread to many parts of the body
4) short-lived effects vs long lasting effects