spritzen
to inject
To inject a liquid into the body or an object with a syringe.
Die Ärztin musste ihm ein Schmerzmittel spritzen.
The doctor had to inject him with a painkiller.

to inject / spray
Loading your saved state.
to inject
To inject a liquid into the body or an object with a syringe.
Die Ärztin musste ihm ein Schmerzmittel spritzen.
The doctor had to inject him with a painkiller.

The verb 'spritzen' (to inject/spray) is closely connected to the noun 'die Spritze' (syringe; sprayer). A 'Spritze' is the tool used to inject or spray liquids, which explains the basic meaning of the verb.
Der Gärtner füllte die Spritze mit Wasser, um die Pflanzen zu spritzen.
The gardener filled the sprayer with water to spray the plants.
In medical contexts, 'spritzen' (to inject) is often used with two objects: the person receiving the injection is in the dative, and the medication is in the accusative.
Der Arzt spritzte dem Patienten ein starkes Schmerzmittel.
The doctor injected the patient with a strong painkiller.
In its medical meaning, the verb is often combined with words like 'Insulin' (insulin), 'ein Medikament' (a medication), 'eine Impfung' (a vaccination), or 'ein Betäubungsmittel' (an anesthetic).
Diabetiker müssen sich regelmäßig Insulin spritzen.
Diabetics have to inject themselves with insulin regularly.
When you spray a person or thing with a liquid, you often use the structure: 'jemanden/etwas mit etwas (Dativ) spritzen' (to spray someone/something with something).
Er hat mich aus Versehen mit dem Gartenschlauch nass gespritzt.
He accidentally sprayed me wet with the garden hose.
In connection with baking and cooking, 'spritzen' (to pipe) means to apply a soft mass such as whipped cream or dough with a piping bag. Typical objects are 'Sahne' (whipped cream), 'Creme' (cream), or 'Verzierungen' (decorations).
Für die Dekoration spritzte sie kleine Schokoladenherzen auf den Kuchen.
For the decoration, she piped small chocolate hearts onto the cake.
When it comes to craftwork or industry, 'spritzen' often means to apply paint or varnish with a spray gun. You can recognize this meaning from words like 'Lack' (varnish/paint), 'Farbe' (paint), 'Auto' (car), or 'Wand' (wall).
Die Werkstatt muss den ganzen Kotflügel neu spritzen.
The workshop has to respray the whole fender.
to paint / to cancel
'streichen' and 'spritzen' can both have to do with paint on a surface. The difference lies in how the paint is applied. With 'streichen', you normally use a brush or roller and move it across the surface. With 'spritzen', paint or varnish is spread onto the surface using pressure, for example with a spray gun. The words can be confused because in the end, in both cases, there is paint on the wall, the car, or the piece of furniture. For walls in everyday life, people usually say 'streichen'; for paintwork or refinishing, 'spritzen' often fits better.

In der Werkstatt spritzt der Lackierer die Autotür neu.
In the workshop, the painter resprays the car door.
Am Wochenende streichen wir das Kinderzimmer hellblau.
At the weekend, we are painting the children's room light blue.