AS content for biopsych

What is the nervous system divided into

The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system (CNS), made up of the brain and spinal cord, processes information and coordinates a response.

What is the peripheral nervous system divided into

The PNS is further divided into the somatic nervous system and the autonomic nervous system (ANS). The somatic nervous system carries sensory information from the senses to the CNS and motor commands from the CNS to the muscles. It also controls reflex actions, which are rapid and involuntary responses to stimuli

What is the autonomic nervous system divided into

The ANS regulates involuntary functions as heart rate and digestion and is split into the sympathetic and parasympathetic nervous systems.

What do the sympathetic and parasympathetic nervous systems do

The sympathetic nervous system prepares the body for fight or flight by increasing heart rate and redirecting blood flow to muscles, while the parasympathetic system promotes rest and digest responses by slowing the heart rate and supporting digestion.

What are the three main types of neuron

There are three main types of neuron: sensory, relay, and motor.

What are sensory neurons

Sensory neurons carry information from the senses via the peripheral nervous system to the central nervous system (CNS); this is known as the afferent pathway. They have long dendrites to receive sensory input and short axons.

What are relay neurons

Relay neurons are found within the CNS and connect sensory neurons to motor neurons or other relay neurons. They have short dendrites and short axons.

What are motor neurons

Motor neurons carry impulses from the CNS to effectors in the body, such as muscles or glands — the efferent pathway. They have short dendrites and long axons.

Describe the structure of a neuron

Neurons are nerve cells that carry information from the senses and body to the brain and back again. They vary in size but share key structures. Each neuron has a cell body containing a nucleus, which holds genetic material. Dendrites extend from the cell body and receive electrical impulses from other neurons. These impulses travel along the axon, a long fibre that carries signals away from the cell body. The axon is insulated by a myelin sheath, which speeds up transmission. Gaps in the sheath called nodes of Ranvier allow impulses to jump. At the axon terminals, vesicles in the terminal buttons release neurotransmitters into the synapse.

Describe synaptic transmission

Synaptic transmission is the process where neurons communicate chemically across a synapse. When an electrical impulse (action potential) reaches the presynaptic terminal, it causes vesicles to release neurotransmitters into the synaptic cleft. These neurotransmitters then bind to specific receptor sites on the postsynaptic membrane. Depending on the type of neurotransmitter, this binding can cause excitation, making the postsynaptic neuron more likely to fire, or inhibition, making it less likely to fire. The chemical message is converted back into an electrical impulse in the postsynaptic neuron. Any leftover neurotransmitters are then broken down by enzymes or taken back into the presynaptic neuron through reuptake.

tell me about the endocrine system

The endocrine system is a secondary regulatory system that controls physiological processes through chemical messengers called hormones.

Glands release hormones directly into the bloodstream, where they travel to target cells in different parts of the body that have specific receptors for those hormones.

Each hormone affects behaviour or bodily functions differently.

The pituitary gland, known as the master gland, regulates other endocrine glands and is controlled by the hypothalamus. Proper hormone levels at the right times are essential for normal body function.

Give examples of the endocrine system

• The pineal gland releases melatonin, which helps regulate sleep.
  
  

• The ovaries produce oestrogen and progesterone, which control the menstrual cycle.
  
  

• The pituitary and adrenal glands work together in the fight-or-flight response to stress.

Outline the flight or fight response

The fight or flight response is a physiological reaction to a perceived threat that prepares the body to either confront or escape danger. When a threat is detected, the amygdala in the brain sends a distress signal to the hypothalamus, which activates the sympathetic branch of the autonomic nervous system. This triggers the adrenal medulla to release the hormones adrenaline and noradrenaline into the bloodstream. These hormones cause several physiological changes, including increased heart rate and blood pressure, faster breathing, dilated pupils, inhibition of digestion, and redirected blood flow to the muscles. Once the threat has passed, the parasympathetic nervous system is activated to return the body to a calm, resting state.